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National Water and Climate Center

 

Field Office Guide to Climatic Data

Table of Contents

Content Manager: Jolyne Lea


Introduction [TOC]

The Natural Resources Conservation Service is charged with management of not only soil, but all five SWAPA resources (soil, water, air, plants, animals), and human considerations. SWAPA management requires an understanding of the resources, as well as interactions between resources. Many concerns about the resources can be addressed through climate information and specific climatic data.

Climate is an important factor driving the agriculture of a given region (along with soils, water available for irrigation, societal influences, economics, others). Under many situations, climate is THE determining factor which defines which crops can be grown in an area. For instance, although the soils and economics of North Dakota may support growing cotton, the climate there (specifically temperature and precipitation) would not allow cotton to grow and mature.

This publication concerning climatic data is oriented to the NRCS role in American agriculture and natural resource conservation. It describes the NRCS National Water & Climate Center (NWCC) and its network of liaisons in each NRCS state office.


How to Use this Guide [TOC]

This guide is divided into 7 sections. Section 1 contains detailed information about climatic data elements, measurement methods, and problems associated with collecting climatic data. Sections 2, 3, and 4 provide material to help understand data collection systems. Section 5, Climate Terminology, contains definitions of climatic terms. Section 6 explains how climatic information can be obtained. Climatic data needs associated with a particular conservation practice are listed in Section 7.


1 Climatic Data Element Descriptions, Measurement Methods, and Errors Associated with it's Collection. [TOC]

The following description of climatic data elements is a condensation of the material contained in the National Weather Service Observing Handbook No.2, Cooperative Station Observations, the Weather Station Handbook an Interagency Guide for Wildland Managers, and the American Meteorological Society Glossary of Meteorology.

Statistical analysis of climatic data generates descriptive information which reflects the average atmospheric conditions at a location, as well as generating probabilities that extreme events will occur. Any statistical analysis of climatic data, due mainly to the limited number of samples available, must follow the rules for statistical analysis. An important rule governing small sample analysis requires a minimum of 30 samples. This does not mean that climatic data with less than 30 years of data can not be analyzed, but that some adjustment be made to estimate what a 30 sample set would produce.

AIR TEMPERATURE - Temperature is a measure of the hotness or coldness of air. It is measured on some definitive temperature scale. Two scales are commonly used. The Fahrenheit and Centigrade temperature scales establish the freezing of water at 32/0 degrees respectively and boiling point at 212/100 degrees respectively. The Fahrenheit scale is used most frequently in the US and Centigrade throughout the rest of the world. Air temperature is usually measured with either a liquid-in-glass maximum and minimum thermometer mounted in a vented, wooden box or with an electronic sensor.

It is important that thermometers be shaded from sunlight to avoid an erroneously high measured temperature. Instrument shelters are designed to rectify this problem. For more information on instrument shelters, see the Weather Station Handbook - an Interagency Guide for Wildland Managers.

EVAPORATION - Evaporation is the physical process by which a liquid is transformed to a gaseous state. Evaporation is influenced by solar radiation, air temperature, vapor pressure, wind, and possibly atmospheric pressure. Evaporation varies with latitude, altitude, season, time of day, and sky condition. Accurate evaporation readings requires careful maintenance of an evaporation pan which contains water. The water depth is measured daily and adjusted for any precipitation which may occur.

PRECIPITATION - Precipitation refers to all forms of water, liquid or solid, that fall from the atmosphere and reach the ground. Precipitation includes, but is not limited to, rain, drizzle, snow, hail, graupel, sleet, and ice crystals. It is one of the most basic data elements collected by any climate station. Dew, frost and rime are excluded, since they are a result of water vapor in air condensing or freezing onto a surface.

The standard U.S. precipitation gage has an eight inch diameter mouth and height of about 30 inches. Non-recording gages simply collect precipitation; amount of precipitation must be measured by an observer. Recording gages have instrumentation which records the time, duration, and intensity of precipitation. Most recording gages store information on a paper strip, which is generally changed weekly by an observer. Precipitation intensity and duration, useful information for many NRCS design activities, can be derived from information gathered by precipitation gages.

The biggest factor in precipitation measurement error is wind. Strong winds during precipitation events can cause considerable differences between measured and actual precipitation. Measurement errors can also result from small amounts of dew, frost, and rime accidentally included in the total measured precipitation. Even with careful placement, all gages underestimate the real precipitation, particularly with snowfall.

NEW SNOW - New snow is the incremental amount of snow that has fallen since the last snow depth observation. Delineating between new snow and old snow presents a challenge. A snow board (generally a sheet of plywood) can provide an artificial surface at the top of the existing snow. Snow boards are laid on top of old snow when there is any possibility of new snow falling. After each observation of new snow, the board is cleaned and placed in a new location. Board placement and measurement location are the greatest source of error in determining new snow.

SNOW DEPTH - Snow depth is the actual depth of snow on the ground at the time of measurement. Snow depth is usually measured daily and determined to the nearest whole inch with a calibrated stick, such as that used with the 8-inch non-recording rain gage, or a ruler or yardstick. Snow should be measured in several locations and averaged to avoid errors induced by drifted snow.

SNOW WATER EQUIVALENT - The water equivalent of snow is the depth of water that would be obtained by melting the snow cover. Water equivalent of snow is continuously measured (weighed) by recording gages which are winterized with an antifreeze solution. For non-recording gages, the snow catch collected by the standard rain gage (with the funnel and small tube removed) is melted by adding a known amount of warm water. The total amount is then measured and the added amount of warm water subtracted to yield the observed water equivalent. Most snow water equivalent measurement errors are associated with not selecting a representative location or the mechanics of subtracting water added to the total catch.

SOIL TEMPERATURE - Soil temperature measures the hotness or coldness of soil. Soil temperature is very important to the agricultural industry. Most seeds require a certain soil temperature in order to germinate. Soil temperatures are commonly measured at 2, 4, 8, 20, 40, 60, and 120 inches with the 4 inch reading being the most frequently observed. Readings are usually observed and recorded daily. Maximum, minimum, and current temperatures are generally recorded above 8 inches. At greater depths, where temperature changes more slowly, only the current temperature is normally recorded. Different species of plants have specific soil temperature ranges in which they will grow.

SOLAR RADIATION - INCOMING - Incoming solar radiation is the total electromagnetic radiation emitted by the sun striking the earth. Much solar radiation is absorbed by air molecules, reflected back into space, or refracted as it passes through the atmosphere. A pyrheliometer measures the direct solar radiation that passes through the atmosphere unimpeded. It consists of an enclosed radiation sensing element with a small aperture through which the direct solar rays enter. A pyranometer measures the combined incoming direct solar radiation and diffuse sky radiation. It is mounted such that it views the entire sky. Both instruments can be connected to electronic recording devices to collect the measurements. Solar radiation sensors must be cleaned regularly and exposed properly to accurately measure solar radiation.

WIND - Wind is the motion of air relative to the surface of the earth. Wind speed and direction, the two primary elements, are usually measured with an anemometer and wind vane, respectively. Wind speed is generally measured in miles per hour; direction is measured in degrees to the nearest ten(s) (10 to 360) with 360 degrees being north, 90 degrees being east, 180 degrees representing south, and 270 degrees being west. Wind measurement accuracy is primarily influenced by sensor height and nearby objects.


2 Climate Station Metadata [TOC]

Climate Stations are locations at which climatic data are gathered. Biographical and index information describing the climatic station, called "Metadata", are used in conservation applications and resource evaluations.

STATION ID - Identification number for the climate station assigned by the agency responsible for the particular station.

STATION NAME - The full name of the climate station as recognized by the agency responsible for the climate station.

STATION LATITUDE - Latitude defines a site's location based on its relative distance from the equator going toward the North or South poles. Station latitude is measured in degrees, minutes, and seconds, with 0 degrees being on the equator, and 90 degrees north or south being the North and South Poles, respectively. The latitude of a particular climate station is determined by the agency managing the station and is generally recorded to the nearest minute.

STATION LONGITUDE - Longitude defines a sites relative distance, up to 180 degrees, west or east of a North-South line running through Greenwich, England. The longitude of a particular station is determined by the agency managing the station. Measurement is generally made to the nearest minute.

STATION ELEVATION - The elevation of a climate station is usually measured in feet above mean sea level.


3 Climatic Element [TOC]

A climatic element is a measured parameter which helps to specify the climate of a specific location or region, such as precipitation, temperature, wind speed and humidity. Descriptive terminology for climatic elements are:

ELEMENT NAME - The full description of the element being referenced at the climate station (i.e. maximum temperature).

ELEMENT ID - Is a shortened identifier for the element, usually 4 characters in length (i.e. TMAX(maximum daily temperature), TMIN(minimum daily temperature), PRCP(precipitation, etc).

ELEMENT DURATION - The interval between measurements of a data element. Common data element durations available for the station could include monthly, daily, or hourly.


4 Climate Data Measurement Networks [TOC]

National Weather Service Cooperative Station Network

Cooperative stations generally record daily precipitation and/or maximum and minimum temperature. Several other weather parameters may also be observed, such as evaporation, wind movement, and soil temperature.

The following table lists specific climate elements and the number of National Weather Service stations which measure it:

DATA ELEMENT              NUMBER OF 
                      MEASURING STATIONS 
 
Precipitation              10,700 
Snow Depth                 10,700  
New Snow                   10,700  
Temperature                 7,000  
Wind                          500  
Evaporation                   300  
Incoming Solar Radiation      250  
Soil Temperature              300  

Natural Resources Conservation Service (NRCS)

The NRCS operates an automated network of approximately 600 stations in the western U.S. called SNOTEL (SNOwpack TELemetry). Begining October 1st these stations report accumulated seasonal precipitation , snow water equivalent, and temperature (maximum, minimum, current and average) daily. This network was established in the late 1970s to support water supply forecasting. It uses meteorburst technology to transmit data from remote sites to data gathering locations. SNOTEL augmented and partially replaced the cooperative network of manual snow courses that NRCS acquired and established the mid 1930s.


5 Climate Glossary [TOC]

The following lists terms which provide descriptive information for climatic datasets:

ALBEDO - The ratio of the amount of radiation reflected by a body to the amount of radiation incident upon it; expressed as a percentage.

CLIMATE - the synthesis of weather, or averaging of weather conditions over a given time period.

DEGREE DAYS, COOLING - A value used to estimate the energy requirements for air conditioning of homes and buildings. One cooling degree day is given for each degree the daily mean temperature is above 75 degrees Fahrenheit.

DEGREE DAYS, GROWING - Growing degree days (GDD) measures the day to day accumulation of the difference between the average daily temperature and a threshold temperature for a specific crop. GDD's give an indication of the amount of heat available for crop growth.

DEGREE DAYS, HEATING - A value used to estimate the energy requirements for heating homes and buildings. One heating degree day is given for each degree the daily mean temperature is below 65 degrees Fahrenheit.

DEWPOINT - The temperature to which air is cooled for water vapor to begin condensing.

DRIZZLE - Very small, numerous, and uniformly dispersed water drops that may appear to float while following air currents. Unlike fog droplets, drizzle falls to the ground.

DURATION - the period or time increment to which an observed or computed value applies.

EVAPORATION - Evaporation is the physical process by which a liquid is transformed to a gaseous state.

EVAPOTRANSPIRATION (ET) - The combined processes of evaporation and transpiration.

FOG - A visible collection of minute water droplets suspended in the atmosphere near the earth's surface. Fog reduces visibility below one kilometer (0.62 miles).

FREEZE - A freeze occurs at any time the surface air temperature reaches 28 degrees or less. This temperature causes damage to most vegetation except certain species which are resistant to freezing.

FREEZE FREE PERIOD - Freeze free period is the number of consecutive days where the air temperature does not fall below 28 degrees Fahrenheit.

FREEZE, KILLING - A killing freeze occurs at or below 24 degrees Fahrenheit and causes permanent damage to almost all vegetation.

FREEZE FREE PERIOD, KILLING - Killing freeze free period is the number of consecutive days where the air temperature does not fall below 24 degrees Fahrenheit.

FROST - Frost is the process of deposition of frozen atmospheric water vapor on surfaces whose surface air temperature is below 32 degrees Fahrenheit. A frost can occur at any time the surface air temperature falls to 32 degrees Fahrenheit or less. This temperature may cause damage to very young vegetation or vegetation that has no resistance to frost. Most fruit falls in this category.

FROST FREE PERIOD - Frost free period is the number of consecutive days where the surface air temperature does not fall below 32 degrees Fahrenheit.

FROST, FIRST - First Frost is the first date following the growing season that the minimum temperature drops below an index temperature, usually 32 degrees Fahrenheit. The first frost usually occurs in the fall of the year, but it may occur during the winter months, or in some locations may not occur at all.

FROST, LAST - Last Frost is the last date preceding the growing season that the minimum temperature drops below an index temperature, usually 32 degrees Fahrenheit. The last frost usually occurs in the spring of the year but may occur very early in the summer or not at all in some locations. First and Last frosts are analyzed at three temperatures (32, 28, and 24 degrees Fahrenheit) specifically relating to damage caused to vegetation by the sub-freezing temperatures.

GROWING SEASON - Growing Season is the number of consecutive days where the temperature has not gone below an index temperature for specific vegetation. If vegetation is more resistant to cold temperatures the index temperature would be lower. The index temperatures used in growing season analysis usually include 24, 28, and 32 degrees Fahrenheit.

GROWING SEASON PERIOD - Growing Season Period is the period of time, beginning date and ending date, that defines the period that the temperature has not dropped below the index temperature.

HAIL - Precipitation in the form of balls or irregular lumps of ice with a diameter of 5 mm or more, always produced by convective clouds, nearly always cumulonimbus.

HUMIDITY, RELATIVE - A measure of the amount of water in the air compared to the amount of water vapor the air has the potential to hold. (Note: the potential of air to hold water changes with air temperature. Therefore, relative humidity can change as air temperature changes without an actual change in the amount of water vapor.)

INDEX TEMPERATURE - A temperature which denotes the beginning of a specific event such as 28 degrees Fahrenheit. The 28 degree temperature denotes a freeze that can damage plants.

NORMAL - "Normal" is an average of any of the climatic elements calculated for a specific time period. The beginning and ending years of the normal period are established by the World Meteorological Organization. This organization has defined the current standard averaging period for "Normals" as 1971 through 2000. Normals have been established as the standard period that will be used in analysis of climatic data to allow for comparable descriptive information representative of average conditions over the time period.

PERIOD OF RECORD - The time interval during which meteorological and climatic data have been gathered at a climatic station.

PRECIPITATION - Precipitation refers to all forms of water, liquid or solid, that fall from the atmosphere and reach the ground. Precipitation includes, but is not limited to, rain, drizzle, snow, hail, grapple, sleet, and ice crystals.

PROBABILITY - Probability is a statistical process that provides for the analysis of data to determine the potential of an individual value to occur at a specified time, in a given year, or in a given period of time. An example might indicate that a certain value has a 10 percent chance of occurrence in any year, or that the value has a chance of returning once in a period of ten years.

RAIN - Precipitation in the form of liquid water drops which have diameters greater than 0.02 in (0.5 mm).

WIND ROSES - A type of analysis that describes wind measurements graphically and tabularly as a combination of the cardinal direction that the wind was coming from and the average speed from that direction for a particular time interval.

SLEET - A type of precipitation consisting of transparent or translucent pellets of ice 5 mm or less in diameter. Sleet forms when raindrops fall through a layer of below-freezing air near the earth's surface.

SNOW WATER EQUIVALENT - The water equivalent of snow is the depth of water that would be obtained by melting the snow cover.

SOLAR RADIATION - The total amount of energy emitted by the sun.

SOLAR RADIATION, INCOMING - Incoming solar radiation is the total electromagnetic radiation emitted by the sun striking the earth.

TEMPERATURE - Temperature is a measure of the internal energy of molecular motion in a substance.

THRESHOLD TEMPERATURE - A temperature that denotes the boundary condition for a specific event. For example, a crop specific temperature below which the growth of that crop is minimal.

TRANSPIRATION - The process by which water in plants is transferred to the atmosphere as water vapor.

WEATHER - the instantaneous or short-term state of the atmosphere.

WIND - Wind is the motion of air relative to the surface of the earth.


6 National Water & Climate Center/Climatic Data Access Network [TOC]

The Natural Resources Conservation Service's National Water & Climate Center was created to provide the climatic data analyses needed by NRCS employees and offices to perform conservation activities. Each state and national center has been assigned a Climatic Data Liaison (CDL) to deliver climatic data to field offices as well as other offices in the state requiring climatic data. These Climatic Data Liaisons make up what is known as the Climatic Data Access Network (CDAN). CDAN provides a corp of knowledgeable individuals to assist NRCS field offices in the analysis of climatic data.

The mission of NWCC/CDAN is to access, obtain, evaluate, manage, and disseminate the climatic data needed to support agency programs and activities nationally. The Vision of NWCC/CDAN is "A dynamic, agency-wide climate service network -- providing data and analyses required for integrated ecosystem management."

A wide variety of daily, monthly, and annual data are available through NWCC/CDAN, including air and soil temperature, evaporation, wind movement, snow depth, snow water equivalent and precipitation. Climatic interpretations (probabilities and statistical summaries) for temperature and precipitation, growing season and construction information, rainfall frequency, and information for agronomic and engineering models are available through the Network.

The following examples demonstrate the variety of information available through NWCC/CDAN:


TEMPERATURE AND PRECIPITATION SUMMARY (TAPS) [TOC]

The TAPS table gives a month by month summary and probability analysis of temperature and precipitation.

TAPS Station : DECORAH, 192110 
Start yr. - 1971   End yr. - 2000 
Temperature:     30 years available out of  30 requested in this analysis  
Precipitation:   30 years available out of  30 requested in this analysis  
          |              Temperature          |        Precipitation  
          |-----------------------------------|----------------------------  
          |     |     |     |2 yrs in 10|     |     |2 yrs in 10|  
          |     |     |     | will have | avg |     | will have |avg no |  
          |-----|-----|-----|-----------|no of|     |-----------|of days|avg  
  Month   | avg | avg | avg |max  | min |grow | avg | less| more|w/ 0.10|snow-  
          |daily|daily|     |temp.|temp.|deg  |     | than| than|inch or|fall  
          | max | min |     |>than|<than|days*|(in.)|(in.)|(in.)|more   
------------------------------------------------------------------------------  
January   | 23.7|  5.3| 14.5|  49 | -29 |    1| 0.74| 0.27| 1.14|   2   |  7.0  
February  | 29.6| 10.7| 20.1|  54 | -22 |    3| 0.82| 0.32| 1.29|   2   |  7.2  
March     | 42.0| 23.6| 32.8|  73 | -10 |   55| 1.89| 1.05| 2.64|   4   |  7.5  
April     | 58.2| 36.3| 47.2|  84 |  14 |  256| 3.42| 1.96| 4.71|   6   |  1.6  
May       | 70.8| 47.7| 59.2|  89 |  27 |  597| 3.82| 2.60| 4.94|   7   |  0.0  
June      | 79.7| 56.7| 68.2|  95 |  39 |  846| 4.20| 2.29| 5.89|   6   |  0.0  
July      | 83.7| 61.4| 72.6|  97 |  46 | 1010| 3.99| 2.28| 5.51|   6   |  0.0  
August    | 81.5| 59.0| 70.3|  95 |  42 |  937| 4.03| 2.04| 5.76|   6   |  0.0  
September | 72.7| 50.7| 61.7|  91 |  29 |  651| 3.93| 1.53| 5.95|   6   |  0.0  
October   | 61.0| 39.9| 50.5|  84 |  18 |  339| 2.27| 1.07| 3.31|   4   |  0.2  
November  | 43.8| 27.0| 35.4|  67 |   1 |   65| 1.68| 0.65| 2.64|   4   |  3.4  
December  | 28.3| 12.1| 20.2|  56 | -21 |    5| 1.21| 0.63| 1.73|   3   |  9.7  
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
Yearly :  |-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
  Average | 56.3| 35.9| 46.1| --- | --- | --- | --- | --- | --- | ---   |  ---  
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
  Extreme |  101|  -39| --- |  98 | -31 | --- | --- | --- | --- | ---   |  ---  
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
  Total   | --- | --- | --- | --- | --- | 4764|32.01|26.89|36.67| 56   | 36.5  
----------|-----|-----|-----|-----|-----|-----|-----|-----|-----|-------------  
------------------------------------------------------------------------------  
 
     *A growing degree day is a unit of heat available for plant growth.  
It can be calculated by adding the maximum and minumum daily temperatures,   
dividing the sum by 2, and subtracting the temperature below which growth  
is minimal for the principal crops in the area (Threshold :  40.0 deg. F)  


FROST FREE DAYS (FROST) [TOC]

The FROST table provides information on the average date of the last temperature below 24, 28, and 32 degrees Fahrenheit in the spring, and the average date of the first temperature below 24, 28, and 32 degrees Fahrenheit in the fall, at probabilities of 10, 20, and 50%.

FROST Station : DECORAH, 192110  
Start yr. - 1971   End yr. - 2000  
Requested years of data:    30  Available years of data:  30  
Spring: Missing data years       24 deg =  0, 28 deg =  0, 32 deg =  0  
  Years with no occurrence       24 deg =  0, 28 deg =  0, 32 deg =  0  
  Data years used                24 deg = 30, 28 deg = 30, 32 deg = 30  
Fall:   Missing data years       24 deg =  1, 28 deg =  1, 32 deg =  1  
  Years with no occurrence       24 deg =  0, 28 deg =  0, 32 deg =  0  
  Data years used                24 deg = 29, 28 deg = 29, 32 deg = 29  
    ------------------------------------------------------------------------  
                               |                Temperature  
    ---------------------------|--------------------------------------------  
      Probability              | 24F or lower | 28F or lower | 32F or lower |   
    ---------------------------|--------------|--------------|--------------  
                               |              |              |  
    Last freezing temperature  |              |              |  
     in spring:                |              |              |  
                               |              |              |  
    1 year in 10 later than--  |    April  22 |       May  9 |      May  22   
                               |              |              |  
    2 year in 10 later than--  |    April  17 |       May  3 |      May  16   
                               |              |              |  
    5 year in 10 later than--  |    April   8 |    April  23 |      May   5   
                               |              |              |  
    First freezing temperature |              |              |  
     in fall:                  |              |              |  
                               |              |              |  
    1 yr in 10 earlier than--  |  October   8 |September  26 |September  23   
                               |              |              |  
    2 yr in 10 earlier than--  |  October  13 |   October  1 |September  26   
                               |              |              |  
    5 yr in 10 earlier than--  |  October  23 |  October  12 |  October   4   
                               |              |              |  
    ------------------------------------------------------------------------  

GROWING SEASON (GROWTH) [TOC]
The GROWTH table gives average length of growing season using  
three index temperatures (32, 28, and 24 degrees Fahrenheit) at  
10, 20, 50, 80, and 90% probabilities.  
 
GROWTH Station : DECORAH, 192110 
Start yr. - 1971   End yr. - 2000 
Requested years of data:    30		Available years of data:    30 
Missing data years               24 deg =  1, 28 deg =  1, 32 deg =  1 
Years with no occurrence         24 deg =  0, 28 deg =  0, 32 deg =  0 
Data years used                  24 deg = 29, 28 deg = 29, 32 deg = 29 
    ------------------------------------------------------------------------ 
                               |    Daily Minimum Temperature 
    ---------------------------|-------------------------------------------- 
      Probability              | # days > 24F | # days > 28F | # days > 32F 
                               |              |              |               
      9 years in 10            |    177       |    148       |    131       
                               |              |              |               
      8 years in 10            |    184       |    156       |    138       
                               |              |              |               
      5 years in 10            |    197       |    170       |    151       
                               |              |              |               
      2 years in 10            |    210       |    185       |    163       
                               |              |              |               
      1 year in 10             |    217       |    193       |    170       
                               |              |              |               
    ---------------------------|--------------|--------------|-------------- 

WETLANDS DETERMINATION (WETS) [TOC]
The WETS table gives a month by month summary and probability analysis of  
temperature and precipitation.  The table also provides average length of  
growing season using three index temperatures (32, 28, and 24 degrees  
Fahrenheit) at 50 and 70% probabilities. 
 
				WETS Station : DECORAH, 192110 
				Start yr. - 1971   End yr. - 2000 
	Temperature:     30 years used out of  30 requested in this analysis 
	Precipitation:   30 years used out of  30 requested in this analysis 
 
			          |    Temperature  |  Precipitation 
			          |-----------------|------------------ 
  	  	                  |     |     |     |     |3 yrs in 10| 
			          |     |     |     |     | will have | 
			          |-----|-----|-----|     |-----------| 
			  Month   | avg | avg | avg | avg | less| more| 
			          |daily|daily|     |     | than| than| 
			          | max | min |     |(in.)|(in.)|(in.)| 
			----------------------------------------------| 
			January   | 23.7|  5.3| 14.5| 0.74| 0.37| 0.96| 
			February  | 29.6| 10.7| 20.1| 0.82| 0.44| 1.07| 
			March     | 42.0| 23.6| 32.8| 1.89| 1.28| 2.42| 
			April     | 58.2| 36.3| 47.2| 3.42| 2.36| 4.45| 
			May       | 70.8| 47.7| 59.2| 3.82| 2.96| 4.96| 
			June      | 79.7| 56.7| 68.2| 4.20| 2.80| 5.46| 
			July      | 83.7| 61.4| 72.6| 3.99| 2.75| 5.19| 
			August    | 81.5| 59.0| 70.3| 4.03| 2.55| 5.23| 
			September | 72.7| 50.7| 61.7| 3.93| 2.07| 5.11| 
			October   | 61.0| 39.9| 50.5| 2.27| 1.37| 2.95| 
			November  | 43.8| 27.0| 35.4| 1.68| 0.89| 2.18| 
			December  | 28.3| 12.1| 20.2| 1.21| 0.78| 1.57| 
			----------|-----|-----|-----|-----|-----|-----| 
			----------|-----|-----|-----|-----|-----|-----| 
			Yearly :  |-----|-----|-----|-----|-----|-----| 
			----------|-----|-----|-----|-----|-----|-----| 
			  Average | 56.3| 35.9| 46.1| --- | --- | --- | 
			----------|-----|-----|-----|-----|-----|-----| 
			  Extreme |  101|  -39| --- | --- | --- | --- | 
			----------|-----|-----|-----|-----|-----|-----| 
			  Total   | --- | --- | --- |32.01|28.58|41.55| 
			----------|-----|-----|-----|-----|-----|-----| 
			----------------------------------------------| 
 
	GROWING SEASON DATES   
 
	WETS Station : DECORAH, 192110 
	Start yr. - 1971   End yr. - 2000 
	Requested years of data:    30		Available years of data:    30 
	Missing data years               24 deg =  1, 28 deg =  1, 32 deg =  1 
	Years with no occurrence         24 deg =  0, 28 deg =  0, 32 deg =  0 
	Data years used                  24 deg = 29, 28 deg = 29, 32 deg = 29 
	    ------------------------------------------------------------------------ 
	                               |                Temperature 
	    ---------------------------|-------------------------------------------- 
	      Probability              |     24F      |     28F      |    32F 
	    ---------------------------|--------------|--------------|-------------- 
	                               |             Growing Season Length 
	                               |           Beginning and Ending Dates  
	                               | 
	    5 years in 10           -- |    189 days  |    161 days  |    143 days  
	                               | 4/15 to 10/21  4/31 to 10/ 9  5/13 to 10/ 2  
	                               |              |              | 
	    7 years in 10           -- |    197 days  |    170 days  |    151 days  
	                               | 4/ 9 to 10/23  4/24 to 10/12  5/ 6 to 10/ 4  
	                               |              |              | 
	    ------------------------------------------------------------------------ 

7 Climatic Data and Conservation Practices [TOC]

The following table provides recommendations on the most appropriate climatic data to use in analysis of the practice for application on a particular field. Values refer to the average or normal values for a particular element and time interval but may refer to a special type of analysis for that time interval ie. probability.
The Practice Names are linked to the appropriate standard which can be retrieved in pdf PDF Document format by selecting the practice name.

              Elements    
Practice #   Conservation Practice Applied   Type   prec temp evap wind
                   
560   Access Road     F
575   Animal Trails and Walkways     F
310   Bedding     M M M
314   Brush Management     F M
322   Channel Vegetation     F M M
324   Chiseling & Subsoiling     M
326   Clearing & Snagging     M M
397   Commercial Fishponds     F M M
317   Composting Facility     M M M M
327   Conservation Cover     F M M
328   Conservation Crop Rotation     M M M R
332   Contour Buffer Strips     F M M
330   Contour Farming     M
331   Contour Orchard and Other Fruit Area     M M M
335   Controlled Drainage     F M
340   Cover & Green Manure Crop     M
342   Critical Area Planting     F M M M
589A   Cross Wind Ridges     M M R
589B   Cross Wind Stripcropping     M M R
589C   Cross Wind Trap Strips     F M R
348   Dam, Diversion     F M
402   Dam, Floodwater Retarding     F M
349   Dam, Multiple Purpose     F M
356   Dike   Earthen   F M
362   Diversion     F M
382   Fence     M M
386   Field Border     M M M
393A   Filter Strip     M M M
394   Firebreak     M M M
398   Fish Raceway or Tank     F M M M
395   Fish Stream Improvement     F M M M
399   Fishpond Management     M M M M
400   Floodwater Diversion     F M
404   Floodway     F M
511   Forage Harvest Management     M M M
655   Forest Harvest Trails & Landings     F M
490   Forest Site Preparation     M M M
666   Forest Stand Improvement     M M M
410   Grade Stabilization Structure     F M
412   Grassed Waterway     F M
548   Grazing Land Mechanical Treatment     M M M
561   Heavy Use Area Protection     M M M
422   Hedgerow Planting     M M M
422A   Herbaceous Wind Barriers     M M M R
423   Hillside Ditch     F M
320   Irrigation Canal or Lateral     M M
388   Irrigation Field Ditch     M M
464   Irrigation Land Leveling     M M M
552B   Irrigation Pit or Regulating Reservoir   Regulating Reservoir   M M
552A   Irrigation Pit or Regulating Reservoir   Irrigation Pit   M M
436   Irrigation Storage Reservoir     F M
442   Irrigation System   Sprinkler   F F
447   Irrigation System   Tailwater Recovery   F
441   Irrigation System   Trickle   M M M
443   Irrigation System   Surface & Subsurface   F F F
430   Irrigation Water Conveyance   Pipeline   F M
428   Irrigation Water Conveyance   Ditch and Canal Lining   M M
449   Irrigation Water Management     FD D D
460   Land Clearing     M M
453   Land Reclamation   Landslide Treatment   F M M
456   Land Reclamation   Highwall Treatment   F M
451   Land Reclamation   Fire Control   F M M M
454   Land Reclamation   Subsidence Treatment   F M
455   Land Reclamation   Toxic Discharge Control   F M F M
544   Land Reconstruction   Mine-Current   F M
543   Land Reconstruction   Mine-Abandoned   F M
466   Land Smoothing     M
468   Lined Waterway or Outlet     M M
634   Manure Transfer     M M M
457   Mine Shaft & Adit Closing     M M
482   Mole Drain     M
484   Mulching     M M M
590   Nutrient Management     M M M
500   Obstruction Removal     M
582   Open Channel     M M
512   Pasture & Hayland Planting     F M M
595A   Pest Management     M
516   Pipeline     M
378   Pond     M M
521A   Pond Sealing or Lining   Flexible Membrane   M M
521B   Pond Sealing or Lining   Soil Dispersant   M M M
521C   Pond Sealing or Lining   Bentonite Sealant   M M
521D   Pond Sealing or Lining   Cationic Emulsion-Waterborne Sealant   M M M
521E   Pond Sealing or Lining   Asphalt-Sealed Fabric Liner   M M M
462   Precision Land Forming     M
338   Prescribed Burning     M M M F
528A   Prescribed Grazing     M M
532   Pumped Well Drain     M
533   Pumping Plant for Water Control     M M
550   Range Planting     F M M
562   Recreation Area Improvement     M
566   Recreation Land Grading & Shaping     M M M
568   Recreation Trail & Walkway     M
554   Regulating Water in Drainage Systems     M M
344   Residue Management   Seasonal   M M M
329B   Residue Management   Mulch Till   M M M
329C   Residue Management   Ridge Till   M
329A   Residue Managment   No-till & Strip Till   M
391A   Riparian Forest Buffer     F M
555   Rock Barrier     M
558   Roof Runoff Management     F M
557   Row Arrangement     F M
570   Runoff Management System     F M
350   Sediment Basin     F M
571   Soil Salinity Management-Nonirrigated     M M M
572   Spoil Spreading     M M
574   Spring Development     F M
584   Stream Channel Stabilization     F M
580   Streambank & Shoreline Protection     F M
585   Stripcropping   Contour   M M M
586   Stripcropping   Field   M M
587   Structure for Water Control     F M
606   Subsurface Drain     H D
607   Surface Drainage   Field Ditch   F M
608   Surface Drainage   Main or Lateral   F
609   Surface Roughening     F
600   Terrace     F M
610   Toxic Salt Reduction     F M M M
612   Tree/Shrub Establishment     M M D F
660A   Tree/Shrub Pruning     M M
614   Trough or Tank     M M
620   Underground Outlet     H M
472   Use Exclusion     M
630   Vertical Drain     M
312   Waste Management System     M M
313   Waste Storage Facility     F F F
359   Waste Treatment Lagoon     F M
633   Waste Utilization     FD M M
636   Water Harvesting Catchment     F M
641   Water Table Control     F M
638   Water & Sediment Control Basin     F M M
640   Waterspreading     M M
642   Well     M M
351   Well Decommissioning     M
657   Wetland Development or Restoration     F M M
645   Wildlife Upland Habitat Management     M M
648   Wildlife Watering Facility     F M
644   Wildlife Wetland Habitat Management     M M
380   Windbreak/Shelterbelt Establishment     F M M
650 Windbreak/Shelterbelt Renovation     F M M

M=monthly, D=daily, H=hourly, 15=15 minute, F=frequency, R=roses

prec = Precipitation, temp = Temperature Max & Min, evap = Evaportation, wind = Wind Movement

This page last revised - November 18, 1998