NDAWN Data Information Help

NDAWN Data Information Help
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NDSU Agriculture
NDSU School of
Natural Resource Sciences
NDAWN
Data Information Help
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Overview
Data Information
Station Site and
Equipment Decription
Barley GDD
Canola GDD
Corn GDD
Heating/Cooling DD
Soybean GDD
Sugarbeet GDD
Sugarbeet Cercospora
Sugarbeet Herbicide
Timing
Sugarbeet Root Maggot
Sunflower GDD
Wheat GDD
Weather Data
Current Conditions
Hourly
Daily
Weekly
Monthly
Yearly
NWS Daily Normals
NWS Monthly Normals
Monthly Report
Deep Soil Temperatures
Soil Moisture
Applications
List of Ag Tools
Barley GDD
Canola GDD
Canola Sclerotinia
Corn GDD
Potato Late Blight,
Early Blight,
and P-Days
Soybean GDD
Sugarbeet Cercospora
Sugarbeet Cercospora
Summaries
Sugarbeet Herbicide
Timing Using GDD
Sugarbeet Root Maggot
Sugarbeet GDD
Sugarbeet GDD Multiple
Planting Dates
Sunflower GDD
Wheat GDD/Midge DD
Wheat GDD Multiple
Planting Dates
Wheat & Small Grain
Disease Forecaster
Crop Water Use
Irrigation Scheduler
Insect DD
Heating/Cooling DD
Account
Log in to NDAWN
Data Information
Basic Information
Data Availability on Web Site:
Our goal is to have yesterday's data, through midnight of last night, available
by 7 A.M. CST or earlier every day. Both hourly and daily data are available on
the web site and daily data may also be summarized for weekly, monthly, or
yearly time periods in either English or metric units. North Dakota State
University (NDSU), the Department of Soil Science (DSS), and the NDAWN Center
makes no claim or warranty as to the availability of NDAWN data and/or any
products produced from them.
Data Units:
Data are available in
either English or metric units. The user may choose to switch units after a
data request is completed. The default is English Units.
Time and Date Standards:
You
are urged to pay special attention to times and dates when using NDAWN data.
Times are based on a 24-hour clock where 1200 is noon and 2400 is midnight.
All times indicated are Central Standard Time (CST), even for those stations
located in Mountain Standard Time (MST) zones. WE NEVER USE CENTRAL DAYLIGHT
TIME (CDT).
To convert Central Standard Time (CST) to central daylight time
(CDT) add 1 hour to the CST. For example, 8 a.m. CST is the same as 9 a.m.
CDT.
Daily data are monitored for a calendar day beginning at midnight and ending
on the following midnight Central Standard Time (CST). All dates are specified
in
Year-Month-Day format
. This date format is used because it is the
international standard date notation and it cannot be confused with other
formats.
Instantaneous Data Direct from Stations:
Beginning in 1994 selected stations were equipped with voice synthesizer modems
(Campbell Model VS1) which operate normally for downloading data, but also allow
callers to obtain instantaneous weather information directly from the station.
Producers, pesticide applicators, state and federal agencies, police, and others
can use instantaneous weather data for pesticide application decisions, planning
research activities and weather sensitive operations, responding to emergencies,
etc. In 1998 we began replacing DC112 modems with newer Campbell Model COM300
voice modems equipped with a unique NDAWN vocabulary. By 2003 all stations were
equipped with COM300 or VS1 modems. The list of uses and benefits is endless.
This technology has greatly increased the value and subsequent use of the NDAWN
system.
Variable Measurements
Overview:
Stations measure air temperature,
relative humidity, wind speed, wind direction, solar radiation, station air
pressure at 32 stations (not adjusted to sea level), rainfall, and soil
temperature under a bare soil surface and under a turf covered surface. Stations
also keep track of maximum and minimum air temperature, maximum wind speed, and
the times they occur.
Calculated variables
include potential
evapotranspiration (PET), dewpoint temperature, wind chill temperature, heating
and cooling degree days, and numerous growing degree days. Departures from a
5-year average, depending on the station are available for daily and monthly
data periods. Departures from normal (1991-2020) temperature or rainfall are
also available. These normals were interpolated from National Weather Service
(NWS) Cooperative stations.
Complete variable descriptions
may be found here
, and
information on
measurement heights or equipment is found here
Measurements:
Wind speed and direction are
measured every 5 seconds and are averaged hourly and daily. Air temperature,
relative humidity, solar radiation, and soil temperatures are measured every 60
seconds and are averaged hourly. Air pressure is measured at 15 minute
intervals, but only the values measured on the hour are available on this web
site. Rainfall is measured in 0.01 inch (0.254 mm) increments and is totaled in
10-minute, hourly, and daily intervals.
Stations provide hourly averages or totals for all variables and hourly
maximum wind speed plus daily summaries consisting of maximum and minimum air
temperature, maximum wind speed, times of occurrence, and various totals or
averages for all other variables. Average hourly solar radiation intensity
(Watts/meter2) is converted to total energy per hour. Daily or other averages of
relative humidity are not provided because they are misleading due to its strong
dependence on air temperature.
Get a complete list of all
NDAWN variables
Data tables consisting of hourly, daily, weekly, monthly, or yearly
summarization periods
to data summarization are available
for each station on the web site. In addition, one variable for one or more
stations may be plotted on graphs.
Rain, but NO Snow Measurements:
NDAWN stations use 6-inch diameter tipping bucket gauges to measure rainfall in
0.01 inch (0.254 mm) increments and total it in 10-minute, hour, and daily
intervals. The water runs through a small orifice at the bottom of the funnel
into the tipping bucket. Since snowfall will not run through the orifice, it
cannot be measured. Rainfall is only measured from April through October. All
hourly and daily rainfall data from November through March is flagged with an
"M" to indicate Missing data.
When snow falls during April, May, September, or October, all hourly rainfall
data at affected stations is flagged as Missing (M). Initially the daily data at
these stations are also flagged as missing (M), but later the water (rain)
equivalent of the snow may be estimated. The water equivalent of the snow is the
amount of water (rain) that would have fallen if the snow had been melted. These
estimates are based on data from the nearest NWS Cooperative Stations where
observers measure snowfall and its water (rain) equivalent manually. At
Cooperative Stations snowfall is caught in an 8-inch diameter cylindrical gauge,
and is measured once per day. At observation time the cooperator melts the snow
in the canister and measures the water (rainfall) depth which is the water
equivalent.
Data Summarization
Measurement:
Wind speed and direction are
measured every 5 seconds and are averaged hourly and daily. Air temperature,
relative humidity, solar radiation, bare soil temperature, and turf soil
temperature are measured every 60 seconds and are averaged hourly. Air pressure
is measured at 15 minute intervals, but only the values measured on the hour are
available on this web site. Rainfall is measured in 0.01 inch (0.254 mm)
increments and is totaled in 10-minute, hourly, and daily intervals.
Snowfall is not measured because tipping bucket rain gauges
cannot measure snow
Hourly Data:
All times
indicated are Central Standard Time (CST) using a 24-hour clock where 1200 is
noon and 2400 is midnight. This includes stations in the Mountain Standard Time
Zone. To convert CST to central daylight time (CDT) add 1 hour to the CST. For
example, 8 a.m. CST is the same as 9 a.m. CDT.
WE NEVER USE CENTRAL DAYLIGHT
TIME (CDT)
Hourly averages, totals, and maximums are calculated from the measured values
throughout the hour and are reported for the 60 min (1 hour)
ending at the
indicated central standard times (CST)
. Wind speed and direction are
measured every 5 seconds and air pressure is measured every 15 minutes. All
other variables are measured every 60 seconds.
Maximum wind speed is the greatest wind speed measured during the hour based
on the 5-second measurements. The reported air pressure is the value measured on
that hour. Rainfall is the total amount that fell during the hour. Solar
radiation flux density is measured every 60 seconds and then converted to total
energy per hour. Values for all other hourly variables are averages of the
individual measured values during the hour.
Get a complete
list of all NDAWN variables
Daily Data:
Daily data are
monitored for a calendar day beginning at midnight and ending on the following
midnight Central Standard Time (CST). We NEVER use Daylight Time (CDT).
Daily maximums, minimums, averages, and totals are determined from the
measured values made throughout the day. Wind speed and direction are measured
every 5 seconds. Maximum wind speed is the greatest of all the 5-second wind
speed measurements. All other variables are measured every 60 seconds. Maximum
and minimum air temperatures are the greatest and smallest of the air
temperature measurements, respectively. Hourly totals of solar radiation and
rainfall are summed for all 24 hours to obtain the daily total. Potential
evapotranspiration is a calculated daily total. Values for all other variables
are averages of all measured values throughout the day.
Daily or other averages of relative humidity are not provided because they
are misleading due to its strong dependence on air temperature.
Get a complete list of all NDAWN variables
Rainfall is only measured from April through October because the tipping
bucket gauges cannot measure snowfall. All rainfall data from November through
March is flagged with an "M" to indicate missing data. When rainfall is totaled
over many days the number of missing days precedes the total rainfall amount
for the time period.
Get more information about rain and snow
measurement
Weekly Data:
Weekly data are
calculated by averaging or totaling daily values for the defined 7-day, weekly
periods. Each week's (7-days) summary is reported on one line. Daily variables
such as time of occurrence and average wind direction cannot be summarized in
this manner, and are not available.
Get a complete list of
all NDAWN variables
Rainfall is only measured from April through October because the tipping
bucket gauges cannot measure snowfall. All rainfall data from November through
March is flagged with an "M" to indicate missing data. The total rainfall column
of your table will provide the number of missing days for each week, followed by
the total rainfall, if any, during the remainder of the week.
Get more information about rain and snow measurement
Monthly Data:
Monthly data are
calculated by averaging or totaling daily values for the entire month. Each
month's summary is reported on one line. Daily variables such as time of
occurrence and average wind direction cannot be summarized in this manner, and
are not available.
Get a complete list of all NDAWN
variables
Rainfall is only measured from April through October because the tipping
bucket gauges cannot measure snowfall. All rainfall data from November through
March is flagged with an "M" to indicate missing data. The total rainfall column
of your table will provide the number of missing days for each month, followed
by the total rainfall, if any, during the remainder of the month.
Get more information about rain and snow measurement
Yearly Data:
early data are
calculated by averaging or totaling daily values for the entire year. Each
year's summary is reported on one line. Daily variables such as time of
occurrence and average wind direction cannot be summarized in this manner, and
are not available.
Get a complete list of all NDAWN
variables
Rainfall is only measured from April through October because the tipping
bucket gauges cannot measure snowfall. All rainfall data from November through
March is flagged with an "M" to indicate missing data. The total rainfall column
of your table will provide the number of missing days for each year, followed
by the total rainfall, if any, during the remainder of the year.
Get more information about rain and snow measurement
Data Quality Control
Data quality has the highest priority in the operation of the North Dakota
Agricultural Weather Network (NDAWN) because erroneous data are worse than no
data. In order to prevent erroneous data from being released to the public, two
data quality control procedures are completed daily.
Data are retrieved daily via telephone modem by a
High Plains Regional Climate
Center
(HPRCC) computer. Then a computer program identifies missing and
obviously erroneous values, and provides estimates based on surrounding station
data using an inverse distance weighted algorithm or a regression equation based
on the most highly correlated station. All estimated data are identified with
an "E" flag following the value. Following this initial quality control, data
are loaded into the HPCC data base and sent to the NDAWN data base. If a
station's data are estimated because of communication problems, they will be
replaced with the measured data when they become available.
Secondly, every Monday thru Friday morning, except holidays, NDAWN personnel
compare all estimated data to the original erroneous or dubious data to
determine the cause of the problem so it can be fixed as soon as possible. At
the same time data from all stations are visually compared to those from nearby
stations in order to identify suspicious or erroneous data that the computer
program cannot detect. In addition, average weekly and monthly data are
similarly compared to identify possible calibration or other problems. If these
checks identify erroneous or dubious data, they are estimated.
NDAWN stations are visited at least once each year for preventive
maintenance, inspection, and calibration. All sensors are checked and/or
replaced for refurbishment or recalibration according to manufacturer
specifications and/or our strict preventive maintenance schedule. When daily
quality control identifies a malfunctioning sensor the station is visited as
soon as possible to repair or replace it.
Each station also has a cooperator that visits the station several times
throughout the growing season. The cooperator checks the rain gauge and keeps
the station grounds trimmed.
(See
acknowledgements
Estimated or Missing Data:
Erroneous and most
missing data are estimated and identified by a warning "E" flag following the
value. Missing values are indicated by an "M" flag. Please use judgment before
using any estimated data. We reserve the right to modify any data or information
as deemed necessary. Estimated data may change slightly from day to day.
Data Export:
All table or map data
can be exported or downloaded but you must be logged on. Downloaded data
includes all chosen stations and variables. All downloaded data values are
provided with 3 decimal places to facilitate calculation and eliminate rounding
errors. This does not imply that these data are accurate to 3 decimal places.
Each station name, latitude, longitude, and elevation is included. An extra
field for each variable is reserved for an "E" flag indicating an estimated
value, or "M" flag for Missing value. Nearly all missing values are
estimated.
Climatic Normals: Definitions and Explanation
Get a complete list of all NDAWN normal
variables
Normal Weather versus Abnormal Weather:
The use
of the term "Normal" in climatology and meteorology is often confusing. A
climatic Normal is defined as the average of a variable for a continuous
3-decade (30-year) period. These long-term averages or Normals have been used
most of the past century to characterize climatic elements such as precipitation
and temperature. They are a valuable mathematical concept that can be used to
easily compare climatic conditions between years, or locations by masking the
day to day weather variations. Think of Normals as the long-term average of all
the year-to-year extremes.
Unfortunately, use of the term Normal often implies that varying weather
conditions, or departures (deviations) from "Normal", are somehow abnormal. This
is not true. The strong continental climate of the Northern Great Plains
typically causes temperatures, precipitation, and other climatic elements to
vary widely from day to day or week to week. This large variability is the most
important characteristic of the climate in the Northern Great Plains. Thus, we
expect that our temperatures will often be above or below the Normal.
Calculation of Normals:
A climatic Normal is
defined as the average of a variable such as temperature or precipitation for a
continuous 3-decade (30-year) period. As each decade ends, the oldest decade in
the calculation is dropped and the most recent complete decade is added to the
Normal period. The current climatological normal period is the 30-year period
from 1991 to 2020.
For example, to calculate the Normal maximum temperature for June 6, the
average of the maximum temperature for every June 6th during the 1991-2020
period is calculated. That is, all 30 of the June 6th maximum temperatures are
summed, and then the sum is divided by 30 to get the average, or in this case,
the normal maximum temperature for June 6. This would be repeated for any other
variable.
NDAWN (North Dakota Agricultural Weather Network)
Normals:
Since NDAWN was started in 1989 and stations have been gradually
installed over time the station periods of record range from only 1 to about 14
years, far too short a period to calculate Normals. However, we estimated Daily
Normals for each NDAWN station using the daily Normals from nearby National
Weather Service (NWS) Cooperative stations.
NDAWN Normals were estimated through analysis and interpolation of the
1991-2020 monthly Normals for nearby National Weather Service (NWS) Cooperative
Stations. Maps of monthly and seasonal temperature and precipitation Normals
showed that in most cases there were smooth transitions of temperature and
precipitation across the state. This is expected because the 30-year averages
eliminate much of the daily temperature and precipitation differences between
stations. These maps were subsequently used to determine how each NDAWN station
related to the surrounding nearby NWS stations. For most stations the NDAWN
Normals were calculated by interpolating data from 2 or 3 surrounding stations.
However, when NWS and NDAWN stations were less than 2 or 3 miles apart only one
NWS location was used.
Note: NWS cooperative stations only record temperature and precipitation
data. Thus, only
maximum temperature
average temperature
minimum
temperature
precipitation
heating
degree day
, and
cooling degree day
normals are
available from the NWS cooperative data. Growing degree day normals will be
available through the individual NDAWN applications.
Departure from Normal - Definition and Calculation
Procedure:
A departure from normal is typically used to compare a weather
variable for a specific time period (day, series of days, month, year, etc.) to
the 30-year normal value for the same time period. A departure from normal is a
measure of how much the variable differs from the normal (30-year average)
value. In some cases the departure may be called a deviation from normal. A
deviation in statistics usually refers to the difference between the mean of a
sample of observed measurements and one of those measurements.
The departure from normal (Dep Nml) value is calculated as the mathematical
difference between a weather variable for any specific time period and its
corresponding normal for the same period. For example, the Bowman June Average
Max Temp Departure from Normal (Dep Nml) is calculated as:
Bowman June 2004 Max Temp
Departure from Normal
= Bowman June 2004 Avg Max Temp - Bowman June Avg
Normal Max Temp
= 72.4 °F - 74.0 °F
= -1.6 °F
When Departures from Normal are negative it means the weather variable value
is less than normal, and if the departure is positive the weather variable is
greater than normal.
It is important to compare data values for exactly the same time periods, and
the same location. Departures from normal for all weather variables are
calculated the same way, including derived variables such as average
temperature, growing degree days, insect degree days, and heating/cooling degree
days.
However, when comparing rainfall to normal another variable called the
Percent of Normal Rainfall is often used. This makes it easier for most people
to compare how much rain has fallen compared to what the normal or long term
average is. In this case percentages less than 100% mean less rainfall compared
to normal and percentages greater than 100% means more rain fell than the normal
or long-term average. For example, the Bowman June 2004 Percent of Normal
Rainfall is calculated as:
Bowman June 2004 Percent of Normal
Rainfall
= June 2004 Total / June Normal Total
= 0.96 inch / 3.08 inch
= 31%
The Bowman June 2004 rainfall total of 0.96 inch was only 31% of normal
rainfall, less than one-third of the normal or long-term average value. I
believe this is more meaningful than saying the Bowman June 2004 rainfall Dep
Nml was -2.12 inches.
Departure from a previous year - Definition and
Calculation Procedure:
A departure from a previous year (Dep Prev Yr) is
used to compare a weather variable for a specific time period and year (day,
series of days, month, year, etc.) to the same variable's value from a previous
year for the same time period. The calculation is identical to the departure
from normal calculation, only in this case the previous year's value for the
same time period replaces the normal value.
As an example: Since 2004 was a rather cool summer, it would be interesting
to compare the Bowman July 2004 average minimum temperature with the average
minimum temperature from July 1993 which was a very cool year also. We will
calculate the Bowman July 2004 average minimum temperature departure from the
July 1993 average minimum temperature.
The departure from a previous year (Dep Prev Yr) value is calculated as the
mathematical difference between a weather variable for any specific time period
and its corresponding value in a previous year.
An example using the Bowman
July 2004 and July 1993 average minimum temperature is shown below:
Bowman July 2004 avg min temp
departure from the July 1993 avg min temp
= Bowman July 2004 Avg Min Temp - Bowman July 1993 Avg
Min Temp
= 53.9 °F - 51.3 °F
= 2.6 °F
Another example using Bowman total July Rainfall for 1993 and
2004:
Bowman July 2004 total Rainfall Dep
from 1993
= July 2004 Total - July 1993 Total
= 2.07 inch - 4.87 inch
= -2.80 inch
This means the July 2004 rainfall at Bowman was 2.80 inches less than what
fell in July 1993. The Bowman July 2004 percent of July 1993 rainfall is also
calculated below:
Bowman July 2004 Percent of July
2003 Rainfall
= July 2004 Total / July 1993 Total
= 2.07 inch / 4.87 inch
= 43%
The Bowman July 2004 rainfall total of 2.07 inch was only 43% of the July
1993 rainfall. The copious rainfall in 1993 is one of the main reasons it was so
cool in 1993.
It is important to compare data values for exactly the same time periods, and
the same location. Departures from previous years for all weather variables are
calculated the same way, including derived variables such as average
temperature, growing degree days, insect degree days, and heating/cooling degree
days.
Variable Definitions
Get a complete list of normal variable
definitions.
Date
Year - Month - Day:
This date format is used because it is the international standard date notation.
It cannot be confused with other formats and is readily understood by nearly
everyone.
Time (CST)
All times indicated are Central Standard Time (CST) using a
24-hour clock where 1200 is noon and 2400 is midnight.
WE NEVER USE CENTRAL
DAYLIGHT TIME (CDT).
Central Standard Time is also used at all stations
located in Mountain Standard Time (MST) Zones. To convert CST to central
daylight time (CDT) add 1 hour to the CST. For example, 8 a.m. CST is the same
as 9 a.m. CDT.
Hourly averages, totals, maximums or minimums, are determined
from the values measured throughout the hour and are reported for the 60 min (1
hour) ending at the indicated central standard times (CST). Wind speed and
direction are measured every 5 seconds. All other variables except air pressure
are measured every 60 seconds. Air pressure is measured every 15 minutes, but
only values measured on the indicated hour are reported here. All daily values
are based on a 24-hour period from midnight to midnight (CST).
Air Temperature - Maximum (°F or °C)
Daily:
Maximum air temperature
during a 24-hour period from midnight to midnight (CST). Air temperature is
measured every 60 seconds.
Weekly, Monthly, and Yearly:
The
average of the daily maximum air temperatures for the selected time period.
Air Temperature is measured 5 ft (1.52 m) above the soil
surface with a Temperature / Relative Humidity (RH) Sensor. Air temperature
units are Fahrenheit or Celsius.
Time of Maximum Air Temperature (CST)
Daily:
Time (CST) of occurrence
of the maximum air temperature during a 24-hour period from midnight to midnight
(CST).
Air Temperature - Minimum (°F or °C)
Daily:
Minimum air temperature
during a 24-hour period from midnight to midnight (CST). Air temperature is
measured every 60 seconds.
Weekly, Monthly, and Yearly:
The
average of the daily minimum air temperatures for the selected time period.
Air Temperature is measured 5 ft (1.52 m) above the soil
surface with a Temperature / Relative Humidity (RH) Sensor. Air temperature
units are Fahrenheit or Celsius.
Time of Air Temperature - Minimum (CST)
Daily:
Time (CST) of occurrence
of the minimum air temperature during a 24-hour period from midnight to midnight
(CST).
Air Temperature - Average (°F or °C)
Hourly:
Average of all measured
air temperatures during the hour. Air temperature is measured every 60
seconds.
Daily:
Average of the maximum
and minimum daily air temperatures.
Weekly, Monthly, and Yearly:
The
average of the daily average air temperatures for the selected time period.
Air Temperature is measured 5 ft (1.52 m) above the soil
surface with a Temperature / Relative Humidity (RH) Sensor. Air temperature
units are Fahrenheit or Celsius.
Relative Humidity (%)
Hourly:
Average of all measured
relative humidities during the hour. Relative humidity is measured every 60
seconds.
Daily or other averages of relative humidity are not provided
because they are misleading due to the strong dependence of relative humidity on
air temperature.
Relative Humidity is measured 5 ft (1.52 m) above the soil
surface with a Temperature / Relative Humidity (RH) Sensor.
Soil Temperature - Bare (°F or °C)
Hourly:
Average of all measured
bare soil temperatures during the hour. Bare soil temperature is measured every
60 seconds.
Daily:
Average of all hourly
bare soil temperatures for a 24-hour period from midnight to midnight (CST).
Weekly, Monthly, and Yearly:
Average of all daily average bare soil temperatures for the selected time
period.
Bare soil temperatures are measured at a 4 inch (10 cm) depth
in bare soil (devoid of surface vegetation or cover) with a thermocouple or
thermistor. Bare soil temperature units are Fahrenheit or Celsius.
Soil Temperature - Turf (°F or °C)
Hourly:
Average of all measured
soil temperatures under turf during the hour. Turf covered soil temperatures are
measured every 60 seconds.
Daily:
Average of all hourly
soil temperatures under turf for a 24-hour period from midnight to midnight
(CST).
Weekly, Monthly, and
Yearly:
Average of all daily average soil temperatures under turf for the
selected time period.
Soil temperatures under turf are measured at a 4 inch (10 cm)
depth with a thermocouple or thermistor. Soil temperatures under turf units are
Fahrenheit or Celsius.
Wind Speed (mph or m / sec)
Hourly:
Average of all measured
wind speeds during the hour. Wind speed is measured every 5 seconds.
Daily:
Average of all hourly
average wind speeds for a 24-hour period from midnight to midnight (CST).
Weekly, Monthly, and Yearly:
Average of all daily average wind speeds for the selected time period.
Wind speeds are measured at 10 ft (3 m) above the soil surface
with an anemometer. The wind speed units are miles per hour or meters per
second.
Maximum Wind Speed (mph or m / sec)
Hourly:
The greatest (maximum)
recorded wind speed during the hour. Wind speed is measured every 5 seconds.
Daily:
The greatest (maximum)
wind speed recorded during a 24-hour period from midnight to midnight (CST).
Weekly, Monthly, and Yearly:
Average of all daily maximum wind speeds for the selected time period.
Wind speeds are measured at 10 ft (3 m) above the soil surface
with an anemometer. The maximum wind speed units are miles per hour or meters
per second.
Time of Maximum Wind Speed (CST)
Daily:
Time (CST) of occurrence
of the maximum wind speed during a 24-hour period from midnight to midnight
(CST).
Wind Direction (degrees)
Hourly:
Average of all measured
wind directions during the hour. Wind direction is measured every 5 seconds.
Daily:
Average of all measured
wind directions for a 24-hour period from midnight to midnight (CST). This
measurement may not be very meaningful when the wind direction is extremely
variable.
Weekly, Monthly, and Yearly:
Wind direction is not meaningful when averaged for a selected time period such
as a week, month or year. For example, if you average 22.5° which is a
north-northeast wind (NNE) and 337.5° which is a north-northwest wind (NNW)
you get 180° which is a south wind (S) even though the wind never came from
180° (S).
Wind direction is the direction from which wind is
blowing (degrees clockwise from north) measured 10 feet (3 m) above the soil
surface (North = 0°; NE = 45°; E = 90°; S = 180°; SW = 225°;
W = 270°; etc.) with a wind vane. Measurements are taken every 5 seconds.
Wind direction units are degrees.
Wind Direction Standard Deviation (degrees)
Hourly:
Average of all measured
wind direction standard deviations during the hour. Wind direction standard
deviation is measured every 5 seconds.
Daily:
Average of all measured
wind direction standard deviations for a 24-hour period from midnight to
midnight (CST).
Weekly, Monthly, and Yearly:
Wind direction standard deviation for time periods such as a week, month, or
year is not calculated because average wind directions are not meaningful.
Average hourly and average daily standard deviation (StD) of
the wind direction in degrees is a measure of the constancy of the wind
direction. The wind blows from a sector calculated as the Avg Wind Dir +/- 1
Avg Wind Dir StD, about 67% of the time. The larger the StD the more variable
the wind direction. For example, if the average wind direction was 180 and the
Dir StD equals 20 degrees, then the wind was blowing from a sector of 160 to 200
degrees 67% of the time during the day, and from a sector of 140 to 220 degrees
(subtract and add two StD), 95 percent of the time. Wind direction standard
deviation units are degrees.
Solar Radiation (Ly/day or MJ/m
day)
Hourly:
Total incident solar
radiation energy received during the hour. Incident solar radiation flux density
is measured every 60 seconds. These values are averaged for the hour and then
converted to total solar energy received during the hour.
Daily:
Total of all hourly
totals of incident solar radiation energy for a 24-hour period from midnight to
midnight (CST).
Weekly, Monthly, and Yearly:
Average of all daily totals of incident solar radiation for the selected time
period.
Total incident solar radiation flux density is measured in
Watts per meter
at approximately 7 ft (2 m) above the soil surface
with a pyranometer. The solar radiation energy units reported are Langleys (Ly)
per day or Megajoules per meter squared per day (MJ/m
day). One
Langley = 1 calorie per square centimeter.
Potential Evapotranspiration (inch or mm)
Hourly:
PET is not calculated
for hourly time periods.
Daily:
Calculated from daily
values of solar radiation, dew point temperature, wind speed, and air
temperature.
Weekly, Monthly, and Yearly:
Two values are available. The average of all the daily total PET values for the
selected time period, and the sum of all the daily total PET values for the
selected time period.
PET is an estimate of the maximum daily crop water loss when
water is readily available. It is calculated from solar radiation, dew point
temperature, wind speed, and air temperature using the Penman equation and is
based on a crop like alfalfa. The PET units are inches or millimeters (mm).
Rainfall (inch or mm)
Hourly:
Total of all measured
rainfall during the hour. Rainfall is measured in hundredth's of an inch
using a tipping bucket rain
gauge
Daily:
Total of all hourly
rainfall totals for a 24-hour period from midnight to midnight (CST).
Weekly, Monthly, and Yearly:
Total of all daily rainfall totals for the selected time period.
Rain gauges used do not measure snowfall. Therefore winter
month's rainfall is marked with an "M" flag that indicates a missing value.
Summaries of weekly, monthly and yearly data indicate the number of these
missing values.
An "E" flag indicates data have been estimated from
surrounding stations. Estimated rainfall amounts are always suspect because of
the large spatial variation in rainfall.
Total rainfall is measured at approximately 3 ft (1 m)
above the soil surface with a tipping bucket rain gauge. Rainfall units are
inches or millimeters (mm).
Station Barometric Pressure (mb)
Hourly:
Station barometric
pressure is the actual pressure measured at the station's elevation on the
indicated hour. It has NOT been adjusted to sea level. Barometric pressure in
millibars is measured every 15 minutes at 60.9 cm (2 feet) above the soil
surface, but only the values measured on the hour are listed. There are 32 NDAWN
stations that record barometric pressure.
Dew Point Temperature (°F or °C)
Hourly:
Average of all
calculated dew point temperatures during the hour. Air temperature and relative
humidity used for dew point calculations are measured every 60 seconds.
Daily:
Average of all hourly
dew point temperatures for a 24-hour period from midnight to midnight (CST).
Weekly, Monthly, and Yearly:
Average of all daily average dew point temperatures for the selected time
period.
Dew point temperature is the temperature at which some water
vapor in the air would begin condensing to form fog. The dew point temperature
is calculated from the air temperature and relative humidity. Dew point
temperature units are Fahrenheit or Celsius.
Wind Chill Temperature (°F or °C)
Hourly:
Average hourly wind
chill temperature is calculated from hourly averages of air temperature and
wind speed.
Daily:
Average of all hourly
average wind chill temperatures for a 24-hour period from midnight to midnight
(CST).
Weekly, Monthly, and Yearly:
Average of all daily average wind chill temperatures for the selected time
period.
Average daily wind chill temperature (WCT) in °F (°C)
calculated using the new National Weather Service (NWS) Wind Chill formula (as
of Nov. 1, 2001): Wind Chill (°F) = 35.74 + 0.6215T - 35.75(V0.16) +
0.4275T(V0.16) Where, T = Air Temperature (°F) and V = Wind Speed (miles
per hour) measured at 32.8 ft (10 meters) above surface.
The NWS measures wind speed at a height of 32.8 ft (10 meters)
above the surface. NDAWN wind speeds are adjusted to 32.8 feet (10 m) in order
to use the above formula. For more information visit
or
. The wind
chill units are Fahrenheit or Celsius.
Minimum Wind Chill Temperature (°F or
°C)
Daily:
The lowest (minimum)
hourly average wind chill temperature in °F (°C) that occurred during a
24-hour period from midnight to midnight (CST).
Weekly, Monthly, and Yearly:
Average of all daily minimum wind chill temperatures for the selected time
period.
Air Temperature at 9 Meters - Average (°F or
°C)
Hourly:
Average of all measured
air temperatures during the hour. Air temperature is measured every 60 seconds
at 9 meters above the soil surface with a Temperature / Relative Humidity (RH)
Sensor. Air temperature units are Fahrenheit or Celsius.
Relative Humidity at 9 Meters(%)
Hourly:
Average of all measured
relative humidities during the hour. Relative humidity is measured every 60
seconds at 9 meters above the soil surface with a Temperature / Relative
Humidity (RH) Sensor.
Wind Speed at 10 Meters (mph or m / sec)
Hourly:
Average of all measured
wind speeds during the hour. Wind speed is measured every 5 seconds 10 meters
above the soil surface with an anemometer. The wind speed units are miles per
hour or meters per second.
Maximum Wind Speed at 10 Meters (mph or m /
sec)
Hourly:
The greatest (maximum)
recorded wind speed during the hour. Wind speed is measured every 5 seconds
Daily:
The greatest (maximum)
wind speed recorded during a 24-hour period from midnight to midnight (CST).
Wind speeds are measured at 10 meters above the soil surface
with an anemometer. The maximum wind speed units are miles per hour or meters
per second.
Time of Maximum Wind Speed at 10 Meters
(CST)
Daily:
Time (CST) of occurrence
of the maximum wind speed at 10 meters during a 24-hour period from midnight to
midnight (CST).
Wind Direction at 10 Meters (degrees)
Hourly:
Average of all measured
wind directions during the hour. Wind direction is measured every 5 seconds.
Daily:
Average of all measured
wind directions for a 24-hour period from midnight to midnight (CST). This
measurement may not be very meaningful when the wind direction is extremely
variable.
Wind direction is the direction from which wind is blowing
(degrees clockwise from north) measured 10 meters above the soil surface (North
= 0°; NE = 45°; E = 90°; S = 180°; SW = 225°; W = 270°;
etc.) with a wind vane. Measurements are taken every 5 seconds. Wind direction
units are degrees.
Wind Direction Standard Deviation at 10 Meters
(degrees)
Hourly:
Average of all measured
wind direction standard deviations during the hour. Wind direction standard
deviation is measured every 5 seconds.
Daily:
Average of all measured
wind direction standard deviations for a 24-hour period from midnight to
midnight (CST).
Average hourly and average daily standard deviation (StD) of
the wind direction in degrees is a measure of the constancy of the wind
direction. The wind blows from a sector calculated as the Avg Wind Dir +/- 1
Avg Wind Dir StD, about 67% of the time. The larger the StD the more variable
the wind direction. For example, if the average wind direction was 180 and the
Dir StD equals 20 degrees, then the wind was blowing from a sector of 160 to 200
degrees 67% of the time during the day, and from a sector of 140 to 220 degrees
(subtract and add two StD), 95 percent of the time. Wind direction standard
deviation units are degrees.
Air Temperature at 9 Meters - Maximum (°F or
°C)
Daily:
Maximum air temperature
during a 24-hour period from midnight to midnight (CST). Air temperature is
measured every 60 seconds at 9 meters above the soil surface with a Temperature
/ Relative Humidity (RH) Sensor. Air temperature units are Fahrenheit or
Celsius.
Time of Maximum Air Temperature at 9 Meters
(CST)
Daily:
Time (CST) of occurrence
of the maximum air temperature at 9 meters during a 24-hour period from
midnight to midnight (CST).
Air Temperature at 9 Meters - Minimum (°F or
°C)
Daily:
Minimum air temperature
during a 24-hour period from midnight to midnight (CST). Air temperature is
measured every 60 seconds at 9 meters above the soil surface with a Temperature
/ Relative Humidity (RH) Sensor. Air temperature units are Fahrenheit or
Celsius.
Time of Minimum Air Temperature at 9 Meters
(CST)
Daily:
Time (CST) of occurrence
of the minimum air temperature at 9 meters during a 24-hour period from
midnight to midnight (CST).
Normal Variable Definitions
Normal Air Temperature - Average (°F or
°C)
Daily:
The Normal Average Air
Temperature for a specific day is the average of the daily average air
temperatures for the same day each year for 30 years, 1991-2020. For example, to
obtain the Normal Average Air Temperature for June 6, the average air
temperatures for each June 6th during the 1991-2020 period (that is, June 6,
1991; June 6, 1992; June 6, 1993; ... ; June 6, 2019; June 6, 2020) are all
averaged.
Monthly:
The Normal Average Air
Temperature for a specific month is the average of the monthly average air
temperatures for the same month for the 30 years, 1991-2020. For example, to
obtain the June Normal Average Air Temperature, the average air temperature for
each June during the 1991-2020 period (that is, June, 1991, 1992, 1993, ...,
2019, 2020) are all averaged together.
Your Time Period:
The Normal
Average Air Temperature for any designated time period is found by averaging the
daily Normal average air temperature for all days in the time period. For
example, to obtain the Normal Average Air Temperature for the period, June 5-24,
the daily Normal average temperatures for each day in the period, June 5-24
(that is June 5, June 6, June 7, ..., June 23, June 24) are averaged.
Get more information about normals and
departures.
Departure from Normal Air Temperature - Average
(°F or °C)
Daily:
The daily Departure from
Normal Air Temperature - Average is always the difference between the
average air temperature
for a specific day and location, and
the
normal average air temperature
for the same day at the
same location. The normal value is always subtracted from the measured value.
When Departures from Normal are negative it always means the measured value is
below normal, and if the departure is positive the weather variable is always
above normal. For example the:
Departure from Normal Crary
2004-06-01 Average Air Temp
= Crary 2004-06-01 Avg Temp - Crary June 1
Normal Avg Temp
= 52 °F - 60 °F
= -8 °F
This means that Crary's June 1, 2004 average temperature was
8 °F below normal.
Note: Daily Average Temperature
Calculation:
The
daily average air temperature
is
calculated as the average of the maximum and minimum temperatures for the day.
The
normal average air temperature
is calculated as the
average of the normal maximum and normal minimum for the same day.
Monthly, Yearly:
The Departure
from Normal Air Temperature - Average for a month or year is always the
difference between the average air temperature for a specific month or year and
location, and the normal average air temperature for the same month or year at
the same location. The normal value is always subtracted from the measured value
so if the difference is negative the measured value is below normal and if the
difference is positive the measured value is above normal. For example the:
Departure from Normal Crary
June 2004 Average Air Temp
= Crary June 2004 Average Temp - Crary June
Normal Average Temp
= 60 °F - 63 °F
= -3 °F
This means that Crary's June 2004 average temperature was 3
°F below normal.
Note:
The monthly average air
temperature is the average of all the daily average air temperatures during the
month, and the monthly normal average air temperature is the average of all the
daily average normals. Yearly average temperatures and normal temperatures are
calculated similarly.
Your Time Period:
The Departure
from Normal Air Temperature - Average for any time period is always the
difference between the average air temperature for the specified time period and
location, and the normal average air temperature for the same time period and
the same location. The normal value is always subtracted from the measured value
so if the difference is negative the measured value is below normal and if the
difference is positive the measured value is above normal.
Note:
The Average Air
Temperature for any time period is the average of all the daily average air
temperatures in the time period, and the normal average air temperature for the
same time period is the average of all the daily normal average air temperatures
in the time period.
It is absolutely essential to compare measured values and
normals for exactly the same time periods, and the same location. Failure to do
this will result in erroneous comparisons.
Get more information about normals and
departures.
Normal Air Temperature - Maximum (°F or
°C)
Daily:
The Normal Maximum Air
Temperature for a specific day is the average of the daily maximum air
temperatures for the same day each year for 30 years, 1991-2020. For example, to
obtain the Normal Maximum Air Temperature for June 6, the maximum air
temperatures for each June 6th during the 1991-2020 period (that is, June 6,
1991; June 6, 1992; June 6, 1993; ... ; June 6, 2019; June 6, 2020) are all
averaged.
Monthly:
The Normal Maximum Air
Temperature for a specific month is the average of the monthly average maximum
air temperatures for the same month for the 30 years, 1991-2020. For example, to
obtain the June Normal Maximum Air Temperature, the average maximum air
temperature for each June during the 1991-2020 period (that is, June, 1991,
1992, 1993, ...; 2019, 2020) are all averaged together.
Your Time Period:
The Normal
Maximum Air Temperature for any designated time period is found by averaging the
daily Normal maximum air temperature for all days in the time period. For
example, to obtain the Normal Maximum Air Temperature for the period, June 5-24,
the daily Normal maximum temperatures for each day in the period, June 5-24
(that is June 5, June 6, June 7, ..., June 23, June 24) are averaged.
Get more information about normals and
departures.
Departure from Normal Air Temperature - Maximum
(°F or °C)
Daily:
The daily Departure from
Normal Air Temperature - Maximum is the difference between the
maximum air temperature
for a specific day and location, and
the
normal maximum air temperature
for the same day at the
same location. The normal value is always subtracted from the measured value.
When Departures from Normal are negative it always means the measured value is
below normal, and if the departure is positive the weather variable is always
above normal. For example the:
Departure from Normal Crary
2004-06-01 Maximum Air Temp
= Crary 2004-06-01 Max Temp - Crary June 1
Normal Max Temp
= 56 °F - 72 °F
= -16 °F
This means that Crary's June 1, 2004 maximum temperature was
16 °F below normal.
Monthly, Yearly:
The Departure
from Normal Air Temperature - Maximum for a month or year is always the
difference between the average maximum air temperature for a specific month or
year and location, and the normal maximum air temperature for the same month or
year at the same location. The normal value is always subtracted from the
measured value so if the difference is negative the measured value is below
normal and if the difference is positive the measured value is above normal.
For example the:
Departure from Normal Crary
June 2004 Average Maximum Air Temp
Crary June 2004 Average Max Temp - Crary June
Normal Max Temp
= 70 °F - 76 °F
= -6 °F
This means that Crary's June 2004 Average Maximum Air
Temperature was 6 °F below normal.
Note:
The monthly average
maximum air temperature is the average of all the daily maximum air temperatures
during the month, and the monthly normal maximum air temperature is the average
of all the daily normal maximum temperatures in the month. Yearly average
maximum temperatures and normal maximum temperatures are calculated
similarly.
Your Time Period:
The Departure
from Normal Air Temperature - Maximum for any time period is always the
difference between the average maximum air temperature for the specified time
period and location, and the normal maximum air temperature for the same time
period and the same location. The normal value is always subtracted from the
measured value so if the difference is negative the measured value is below
normal and if the difference is positive the measured value is above normal.
Note:
The average Maximum Air
Temperature for any time period is the average of all the daily maximum air
temperatures in the time period, and the normal maximum air temperature for the
same time period is the average of all the daily normal maximum temperatures in
the time period.
It is absolutely essential to compare measured values and
normals for exactly the same time periods, and the same location. Failure to do
this will result in erroneous comparisons.
Get more information about normals and
departures.
Normal Air Temperature - Minimum (°F or
°C)
Daily:
The Normal Minimum Air
Temperature for a specific day is the average of the daily minimum air
temperatures for the same day each year for 30 years, 1991-2020. For example, to
obtain the Normal Minimum Air Temperature for June 6, the minimum air
temperatures for each June 6th during the 1991-2020 period (that is, June 6,
1991; June 6, 1992; June 6, 1993; ... ; June 6, 2019; June 6, 2020) are all
averaged.
Monthly:
The Normal Minimum Air
Temperature for a specific month is the average of the monthly average minimum
air temperatures for the same month for the 30 years, 1991-2020. For example, to
obtain the June Normal Minimum Air Temperature, the average minimum air
temperature for each June during the 1991-2020 period (that is, June, 1991,
1992, 1993, ..., 2019, 2020) are all averaged together.
Your Time Period:
The
Normal Minimum Air Temperature for any designated time period is found by
averaging the daily Normal minimum air temperatures for all days in the time
period. For example, to obtain the Normal Minimum Air Temperature for the
period June 5-24, the daily Normal minimum air temperatures for each day in the
period, June 5-24 (that is June 5, June 6, June 7, ..., June 23, June 24) are
averaged.
Get more information about normals and
departures.
Departure from Normal Air Temperature - Minimum
(°F or °C)
Daily:
The daily Departure from
Normal Air Temperature - Minimum is the difference between the
minimum air temperature
for a specific day and location, and
the
normal minimum air temperature
for the same day at the
same location. The normal value is always subtracted from the measured value.
When Departures from Normal are negative it always means the measured value is
below normal, and if the departure is positive the weather variable is always
above normal. For example the:
Departure from Normal Crary
2004-06-01 Minimum Air Temp
= Crary 2004-06-01 Min Temp - Crary June 1
Normal Min Temp
= 48 °F - 49 °F
= -1 °F
This means that Crary's June 1, 2004 minimum temperature was
1 °F below normal.
Monthly, Yearly:
The Departure
from Normal Air Temperature - Minimum for a month or year is always the
difference between the average minimum air temperature for a specific month or
year and location, and the normal minimum air temperature for the same month or
year at the same location. The normal value is always subtracted from the
measured value so if the difference is negative the measured value is below
normal and if the difference is positive the measured value is above normal.
For example the:
Departure from Normal Crary
June 2004 Average Minimum Air Temp
Crary June 2004 Average Min Temp - Crary June
Normal Min Temp
= 50 °F - 50 °F
= 0 °F
The 0 °F Departure from normal means there was no
difference between the average measured minimum temperatures and the normal
minimum temperatures.
Note:
The monthly average
minimum air temperature is the average of all the daily minimum air temperatures
during the month, and the monthly normal minimum air temperature is the average
of all the daily normal minimum temperatures in the month. Yearly average
minimum temperatures and normal minimum temperatures are calculated
similarly.
Your Time Period:
The Departure
from Normal Air Temperature - Minimum for any time period is always the
difference between the average minimum air temperature for the specified time
period and location, and the normal minimum air temperature for the same time
period and the same location. The normal value is always subtracted from the
measured value so if the difference is negative the measured value is below
normal and if the difference is positive the measured value is above normal.
Note:
The average Minimum Air
Temperature for any time period is the average of all the daily minimum air
temperatures in the time period, and the normal minimum air temperature for the
same time period is the average of all the daily normal minimum temperatures in
the time period.
It is absolutely essential to compare measured values and
normals for exactly the same time periods, and the same location. Failure to do
this will result in erroneous comparisons.
Get more information about normals and
departures.
Normal Heating Degree Days (°F or °C)
Daily:
The Normal Heating Degree
Days (HDD) for a specific date is the average of the Heating Degree Days
calculated for the same date each year for 30 years, 1991-2020. For example, to
obtain the Normal Heating Degree Days for January 6, the Heating Degree Days
calculated for each January 6th during the 1991-2020 period (that is, January 6,
1991; January 6, 1992; January 6, 1993; ... ; January 6, 2009; January 6, 2010)
are all averaged.
Monthly:
The Normal Heating
Degree Days for a specific month is the total of the daily Heating Degree Days
for each day in the month. For example, to obtain the January Normal Heating
Degree Days, the daily Normal Heating Degree Days for each January day (that is,
January 1, January 2, January 3, ..., January 30, January 31) are totaled.
Your Time Period:
The Normal
Heating Degree Days for any designated time period is found by totaling the
daily Normal Heating Degree Days for all days in the time period. For example,
to obtain the Normal Heating Degree Days for the period, February 5-24, the
Normal Heating Degree Days values for each day in the period, February 5-24
(that is February 5, February 6, February 7, ..., February 23, February 24) are
totaled.
Get more information about normals and
departures.
Departure from Normal Heating Degree Days
(°F or °C)
Daily:
The Departure from Normal
Heating Degree Days (HDD) is the difference between the total
heating degree days
for a specific day and location, and the
normal total
heating degree days
for the same day at the same location. The normal value
is always subtracted from the measured value. When Departures from Normal are
negative it always means the measured value is below normal, and if the
departure is positive the measured variable is always above normal. For example
the:
Departure from Normal
Cavalier 2004-02-01 Heating Degree Days
Cavalier 2004-02-01 Heating degree days -
Cavalier February 1 Normal Heating Degree Days
= 71 HDD - 60 HDD
= 11 HDD
This means that Cavalier’s February 1, 2004 heating degree
days were 11 above the daily normal. However, this is often misleading because
HDD are inversely correlated with the air temperature so they represent the
energy required to heat buildings. Therefore, accumulating above normal HDD
means the temperatures were colder than normal, so it takes more energy to heat
your buildings. Of course the reverse is true also. If below normal HDD
accumulate then air temperatures are warmer than normal and it takes less energy
to heat buildings.
Monthly, Yearly:
The Departure
from Normal Total Heating Degree Days for a month or year is always the
difference between the total heating degree days for a specific month or year
and location, and the normal total heating degree days for the same month or
year at the same location. The normal value is always subtracted from the
measured value so if the difference is negative the measured value is below
normal and if the difference is positive the measured value is above normal. For
example the:
Departure from Normal
Cavalier February 2004 Total Heating Degree Days
= Cavalier February 2004 Total Heating degree
days -
Cavalier February Normal Total Heating Degree Days
= 1482 HDD - 1543 HDD
= -61 HDD
This means that Cavalier February 2004 total heating degree
days was 61 HDD below normal. However, this is often misleading because HDD are
inversely correlated with the air temperature so they represent the energy
required to heat buildings. Therefore, accumulating below normal HDD means the
temperatures were warmer than normal, so fewer HDD accumulate, and it takes less
energy to heat your buildings. Of course the reverse is true also. If above
normal HDD accumulate then air temperatures are colder than normal and more HDD
accumulate.
Your Time Period:
The Departure
from Normal Total Heating Degree Days for any time period is always the
difference between the total heating degree days for the specified time period
and location, and the normal total heating degree days for the same time period
and the same location. The normal value is always subtracted from the measured
value so if the difference is negative the measured value is below normal and if
the difference is positive the measured value is above normal.
Note:
The total heating degree
days for any time period is the sum of all the daily heating degree days in the
time period. The
normal
total heating degree days is the sum of all the
daily
normal
heating degree days totals in the time period.
It is absolutely essential to compare measured values and
normals for exactly the same time periods, and the same location. Failure to do
this will result in erroneous comparisons.
Get more information about normals and
departures.
Normal Cooling Degree Days (°F or °C)
Daily:
The Normal
Cooling Degree Days (CDD) for a specific date is the average of the Cooling
Degree Days calculated for the same date each year for 30 years, 1991-2020. For
example, to obtain the Normal Cooling Degree Days for July 6, the Cooling Degree
Days calculated for each July 6th during the 1991-2020 period (that is, July 6,
1991; July 6, 1992; July 6, 1993; ... ; July 6, 2009; July 6, 2010) are all
averaged.
Monthly:
The Normal
Cooling Degree Days for a specific month is the total of the daily Cooling
Degree Days for each day in the month. For example, to obtain the July Normal
Cooling Degree Days, the daily Normal Cooling Degree Days for each July day
(that is, July 1, July 2, July 3, ..., July 30, July 31) are totaled.
Your Time Period:
The
Normal Cooling Degree Days for any designated time period is found by totaling
the daily Normal Cooling Degree Days for all days in the time period. For
example, to obtain the Normal Cooling Degree Days for the period, August 5-24,
the Normal Cooling Degree Days values for each day in the period, August 5-24
(that is August 5, August 6, August 7, ..., August 23, August 24) are totaled.
Get more information about normals and
departures.
Departure from Normal Cooling Degree Days
(°F or °C)
Daily:
The Departure from Normal
Cooling Degree Days (CDD) is the difference between the total
cooling degree days
for a specific day and location, and the
normal total cooling
degree days
for the same day at the same location. The normal value is
always subtracted from the measured value. When Departures from Normal are
negative it always means the measured value is below normal, and if the
departure is positive the measured variable is always above normal. For example
the:
Departure from Normal
Cavalier 2004-07-10 Cooling Degree Days
Cavalier 2004-07-10 Cooling degree days -
Cavalier July 10 Normal Cooling Degree Days
= 9 CDD - 4 CDD
= 5 CDD
This means that Cavalier's July 10, 2004 cooling degree days
were 5 above the daily normal. However, this is often misleading because CDD are
inversely correlated with the air temperature so they represent the energy
required to cool buildings. Therefore, accumulating above normal CDD means the
temperatures were warmer than normal, so it takes slightly more energy to cool
your buildings. Of course the reverse is true also. If below normal CDD
accumulate then air temperatures are cooler than normal so it takes slightly
less energy to cool your buildings or you can open the windows.
Monthly, Yearly:
The Departure
from Normal Total Cooling Degree Days for a month or year is always the
difference between the total cooling degree days for a specific month or year
and location, and the normal total cooling degree days for the same month or
year at the same location. The normal value is always subtracted from the
measured value so if the difference is negative the measured value is below
normal and if the difference is positive the measured value is above normal. For
example the:
Departure from Normal
Cavalier July 2004 Total Cooling Degree Days
= Cavalier July 2004 Total Cooling degree days
Cavalier July Normal Total Cooling Degree Days
= 108 CDD - 121 CDD
= -13 CDD
This means that the Cavalier July 2004 total cooling degree
days was 13 CDD below normal. However, this is often misleading because CDD are
inversely correlated with the air temperature so they represent the energy
required to cool buildings. Therefore, accumulating below normal CDD means the
temperatures were cooler than normal, so fewer CDD accumulate, and it takes less
energy to cool your buildings. Of course the reverse is true also. If above
normal CDD accumulate then air temperatures are greater than normal and more CDD
accumulate.
Your Time Period:
The Departure
from Normal Total Cooling Degree Days for any time period is always the
difference between the total cooling degree days for the specified time period
and location, and the normal total cooling degree days for the same time period
and the same location. The normal value is always subtracted from the measured
value so if the difference is negative the measured value is below normal and if
the difference is positive the measured value is above normal.
Note:
The total cooling degree
days for any time period is the sum of all the daily cooling degree days in the
time period. The
normal
total cooling degree days is the sum of all the
daily
normal
cooling degree days totals in the time period.
It is absolutely essential to compare measured values and
normals for exactly the same time periods, and the same location. Failure to do
this will result in erroneous comparisons.
Get more information about normals and
departures.
Normal Precipitation (inch or mm)
Daily:
The Normal Precipitation
for a specific day is the average of the total precipitation received for the
same date each year for 30 years, 1991-2020. For example, to obtain the Normal
Precipitation for June 6, the precipitation amounts for each June 6th during the
1991-2020 period (that is, June 6, 1991; June 6, 1992; June 6, 1993; ... ; June
6, 2009; June 6, 2010) are all averaged. However, the resultant daily Normal
Precipitation amounts often vary significantly from day to day. To eliminate
this variation the results are smoothed mathematically so that consecutive days
have nearly the same daily Normal precipitation amounts.
Monthly:
The Normal
precipitation for a specific month is the average of the total precipitation
amounts for the same month for the 30 years, 1991-2020. For example, to obtain
the June Normal precipitation, the total precipitation amounts for each June
during the 1991-2020 period (that is, June, 1991, 1992, 1993, ..., 2009, 2010)
are all averaged.
Your Time Period:
The Normal
Precipitation for any designated time period is found by totaling the daily
Normal precipitation for all days in the time period. For example, to obtain the
Normal precipitation for the period, June 5-24, the Normal precipitation values
for each day in the period, June 5-24 (that is June 5, June 6, June 7, ..., June
23, June 24) are totaled.
Please Note:
Precipitation
Normals exist for all calendar days because they are calculated from National
Weather Service (NWS) cooperative stations where snowfall is measured manually.
NDAWN stations only measure rainfall from April through October because the
tipping bucket gauges cannot measure snowfall. All NDAWN rainfall data from
November through March is flagged with an "M" to indicate missing data.
Get more information about rain and snow measurement.
Get more information about normals and
departures.
Departure from Normal Rainfall (inch or mm)
Daily:
The Departure from Normal
Rainfall is the difference between the total
rainfall
for a
specific day and location, and the
normal total rainfall
for the same day at the same location. The normal value is always subtracted
from the measured value. When Departures from Normal are negative it always
means the measured value is below normal, and if the departure is positive the
weather variable is always above normal. For example the:
Departure from Normal Crary 2004-06-01 Rainfall
= Crary 2004-06-01 total Rainfall - Crary June 1
Normal total Rainfall
= 0.01 inch - 0.11 inch
= -0.10 inch
This means that Crary's June 1, 2004 rainfall was 0.10 inch
below the daily normal.
Monthly, Yearly:
The Departure
from Normal Total Rainfall for a month or year is always the difference between
the total rainfall for a specific month or year and location, and the normal
total rainfall for the same month or year at the same location. The normal value
is always subtracted from the measured value so if the difference is negative
the measured value is below normal and if the difference is positive the
measured value is above normal. For example the:
Departure from Normal Crary
June 2004 Total Rainfall
= Crary June 2004 Total Rainfall - Crary June
Normal Total Rainfall
= 1.20 inch - 3.05 inch
= -1.85 inch
This means that Crary's June 2004 total rainfall was 1.85
inches below normal.
Your Time Period:
The Departure
from Normal Total rainfall for any time period is always the difference between
the total rainfall for the specified time period and location, and the normal
total rainfall for the same time period and the same location. The normal value
is always subtracted from the measured value so if the difference is negative
the measured value is below normal and if the difference is positive the
measured value is above normal.
Note:
The total rainfall for any
time period is the sum of all the daily rainfall totals in the time period. The
normal total rainfall is the sum of all the daily normal rainfall totals in the
time period.
It is absolutely essential to compare measured values and
normals for exactly the same time periods, and the same location. Failure to do
this will result in erroneous comparisons.
Get more information about normals and
departures.
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