Temperature and the Water Balance for Oregon Weather Stations

Transcription

1 1C15- [k E55- a 'L Temperature and the Water Balance for Oregon Weather Stations Special Report 150 May 1963 Agricultural Experiment Station Oregon State University Corvallis

2 Contents I. Summary 1 II. Introduction 1 III. Types of Data and Sources 2 Temperature Data 3 Moisture Data 4 Soil Moisture Storage 5 IV. The Need for Evaporation and Transpiration Data 6 V. Reasons for Selecting the Thornthwaite-Mather Procedure 7 Page VI. Assumptions of the Thornthwaite-Mather Procedure and Value and Limitations of the data 8 VII. Potential vs. Actual Evapotranspiration 8 VIII. Cautions in the Interpretation and Use of Water Balance Data 9 IX. Some Applications and Implications of the Data 9 X. Appendices: Lk. Index to Data Tables by Counties 12 1B. Index to Data Tables, arranged alphabetically by stations Map Showing the Location of Oregon Weather Stations, Identified by Data Table Number Tables for Individual Weather Stations 17 XI, Bibliography 126

3 Temperature and the Water Balance for Oregon Weather Stations G. A. Johnsgard I. Summary This report presents a compilation of basic climatic data, based on long-time averages for 209 Oregon weather stations. The data include monthly and annual average maximum, average minimum and average temperatures and precipitation data from U. S. Weather Bureau and other weather stations. The average dates of first and last seasonal occurrence of 32 F. and 28 F. temperature minima are included for 94 stations. The data also include estimated potential evapotranspiration values, derived by the Thornthwaite-Mather procedure (20) and monthly, annual and cumulative estimates of water surpluses and deficits. Estimated potential evapotranspiration values for periods between the first and last seasonal occurrence of 32 F. and 28 0F. temperature minima are recorded for stations with frost free season data. Some limitations and advantages of the Thornthwaite-Mather procedure are reviewed and some possible applications and uses of the data are suggested. II. Introduction This compilation of climatic data was undertaken to characterize and contrast temperature and moisture variables for the major kinds of soils and their areas of occurrence in Oregon. The primary objective of this study is to assemble a uniform set of basic climatic data for a large number of Oregon weather stations located throughout the state. Many important relationships exist between certain aspects of climate and soils. The areas of occurrence of different kinds of soils and certain physical, chemical and biological soil characteristics are related to climate. The use suitability, productivity, management, and conservation requirements of soils may be greatly influenced by climate. The many important relations between soils and climate suggest that a basic set of selected climatic data may be of considerable value as a part of soil characterization data. AUTHOR: Former Professor of Soils, Oregon State University. G. H. Simonson, Assistant Professor of Soils, Oregon State University, was responsible for final preparation of the manuscript and for including certain revisions and additions.

4 -2- III. Types of Data and Sources Two broad classes of data are included in this study -- temperature data and moisture data. The following data have been compiled from long-time averages as a part of a basic set for a selected group of Oregon weather stations. The general sources of data are indicated below. Specific sources are indicated on the table for each weather station. Data tables are presented in an appendix to this report. Temperature data; (in Fahrenheit degrees): Average maximum temperature, monthly and annual Average minimum temperature, monthly and annual Average temperatures, monthly and annual Average dates of the first and last seasonal occurrence of 32 F and 28 F minimum temperatures, and the number of frost free days between these dates. Moisture data; (in inches): Average precipitation, monthly and annual Calculated average potential evapotranspiration, monthly Calculated average potential evapotranspiration, frost free season (32 F minimum) Calculated average potential evapotranspiration, frost free season (28 F minimum) Calculated average moisture surplus, monthly Calculated average moisture deficit, monthly Calculated average cumulative monthly moisture surplus, monthly and annual Calculated average cumulative monthly moisture deficit, monthly and annual Published summaries of U.S. Weather Bureau climatic data for record periods of various lengths were the data sources in most cases. The most common periods for which summaries were available were , or In some cases data summaries were available for segments of these periods and in other cases the only available summaries were for periods, differing in length for different stations, for a period prior to Summaries for "first order" weather stations were for periods greater than 50 years in some cases. Data

5 -3- for the years 1953 to 1959 were summarized for some recently established weather stations to extend the length of the record period. Annual reports from Agricultural Branch Experiment Stations were the source of some data. Frost free season data were drawn in part from a published summary by the U. S. Weather Bureau and in part from the median or 50% probability tables compiled by Eichhorn (15). The following standards were used in selecting data: 1. The records used were for the most recent and longest continuous period for which summaries were available. 2. Stations with record periods shorter than "8 years were excluded in most cases. In a few cases summaries for periods as short as 5 years were used. 3. Records for periods prior to 1930 were used if more recent records for an adequate period were not available. Separate sets of data are included for both a recent period and a period prior to 1930 in a few cases, particularly if the recent record period was quite short. Sources of data and length of record periods are indicated on the data table for each station. In some cases the record periods are not identical for all types of data but all data cover as nearly equivalent periods as possible. The long-time average values presented in this study are inadequate for describing and characterizing various aspects of climate for many purposes. For certain purposes, detailed short-time data are essential and should be consulted. For other purposes, the range of variability or selected statistical indices of variability may be of importance. Extreme values or the frequency and duration of values above or below certain "critical" limits assume a special significance for other purposes. Following is a more detailed account of some considerations in the selection and development of the various kinds of data: Temperature Data Average maximum and minimum temperatures were included, in addition to average temperatures. The principal reason for including average maximum and minimum temperatures is to provide an index of the diurnal range in temperatures, a fact of considerable importance in many biological considerations and for certain other purposes. This may be illustrated by comparing various temperature values for Brookings and Chemult, Oregon. The average, average maximum, and average minimum temperatures for July for Brookings are 59.1 F., 67.8 F., and 50.8 F., respectively; the average maximum and minimum temperatures range 8 to 9 degrees from the average. The same values for Chemult are 59.4 F., 82.9 F., and 35.6 F., respectively; the average maximum and minimum temperatures range 23 to 24 degrees from the average. Obviously, the two stations differ markedly in the day to night range in temperatures during the month of July,

6 -4- a fact not revealed by the similarity in average July temperatures. The differences in day to night temperature for the two stations might be expected to be of considerable importance, particularly in relation to certain biological phenomena. Average temperature, in weather station summaries, is the arithmetic mean of average maximum and average minimum temperature. Inclusion of average maximum and average minimum temperature, from which the average temperatures can be derived, suggests that the latter value could be excluded from the basic set of data for all stations. There are, however, two reasons for including average temperatures. Firstly, average monthly temperatures are required for deriving the heat index, one of the steps in t'he calculation of potential evapotranspiration, in the Thornthwaite-Mather procedure. The average temperature values presented in the tables for the individual stations were those used in calculating potential evapotranspiration. Secondly, data summaries were not always available for identical periods for all temperature values so the record period for average maximum and average minimum temperatures may differ slightly from the record period for average temperatures. In most cases the record periods for the various temperature values are essentially the same. Frost free season data are included for 94 of the stations as footnotes to the tables. These data include the average dates of the first and last seasonal occurrence of 320 and 28 F. temperature minima and the number of days between these dates. The frost free season data at these two temperature levels provide an indication of the seasonal incidence and average length of growing season for frost sensitive crops at the localities where the dates are available. This information supplements the average temperature data for evaluating cropping potential and aids in determining the importance to crop production of the seasonal water surplus and deficit values for the various sections. Moisture Data The average total quantities of precipitation, by individual months and for a calendar year, are indicated by the monthly and annual precipitation data. These values provide an index, or measure, of average moisture supplied from atmospheric sources to the earth's land surface or its vegetative cover, exclusive of condensation and other types of attrition from vapor forms in the atmosphere. Monthly potential evapotranspiration data represent estimates of the average potential amounts of water that may be lost to the atmosphere by evaporation and transpiration from vegetation covered areas with soils at field capacity. These values were derived by a procedure developed by Thornthwaite and Mather (20). The mechanics of the procedure is presented in detail in a recent publication (20) and will not be elaborated in this report. Potential evapotranspiration is defined by Thornthwaite and Mather (19, p.15) as follows: "The amount of water which will be lost from a surface completely covered with vegetation if there is sufficient water in the soil at all times for the use of the vegetation." This definition should probably specify that "sufficient water in the soil" refers to a soil at a moisture content of approximately field capacity.

7 -5- Values of potential evapotranspiration for the frost free season (32 F. and 28 F. minima) are included as part of the footnotes for those stations with frost free season data. cio Monthly moisture surplus and monthly moisture defi2j4are derived, in the Thornthwaite-Mather procedure, by calculating the diff ces between monthly precipitation and monthly potential evapotranspiration. 1 / Months in which precipitation exceeds potential evapotranspiration are moisture surplus months. The moisture surplus for each surplus month is determined by subtracting potential evapotranspiration from precipitation for that month. Months in which evapotranspiration exceeds precipitation are moisture deficit months. The moisture deficit for each deficit month is determined by subtracting precipitatio from potential evapotranspiration for that month. Cumulative moisture surpluses were derived from data for individual surplus months as follows: The amount of the surplus for the first surplus month in the fall, the month representing the beginning of the moisture surplus season, was entered as the cumulative surplus for that month. The amounts of the surpluses for individual succeeding surplus months were added progressively to obtain the cumulative values for successive months of the surplus period. In Oregon the surplus moisture period normally begins in the fall and extends into the following calendar year. For this reason, and because the data are presented on a calendar year basis, it was necessary to carry the December cumulative surplus back to January of the "average" year to allow the continuation of the cumulative process through the entire moisture surplus period. This procedure assumes another "average" year following the one for which the data are presented. This procedure eliminates the necessity of extending the data table beyond a single calendar year. To avoid confusion it is important to emphasize that in the record tables in the appendix, the cumulative moisture surplus is always calculated from the first surplus month in the fall and that the cumulative surplus for January includes surpluses for December and all previous months of the surplus period. Cumulative moisture deficits were derived from data for individual deficit months as follows: The amount of the deficit for the first deficit month in the calendar year was entered as the cumulative deficit for that month. The amounts of the deficits for the individual succeeding months were added progressively to obtain the cumulative values for the successive months of the deficit period. Soil Moisture Storage The "Water Balance" procedure of Thornthwaite and Mather includes consideration of soil moisture storage and rates of water loss from soils and vegetation by evapotranspiration. Reference tables for determining average rates of water loss have been compiled for soils of various root zone water storage capacities (20, pp ). 1/ The terms moisture surplus, moisture deficit, and water balance, as used in this paper differ in meaning from their usage by Thornthwaite and Mather (19) in that soil moisture recharge and utilization are not included in the calculation of these values in this paper. Why 9

8 -6- Inclusion of soil moisture recharge (storage) data and utilization (rates of water loss) data to arrive at an estimate of "actual" evapotranspiration rather than potential evapotranspiration would affect the estimates of water deficits and surpluses. The utilization by plants of soil-stored surplus water would reduce the actual water deficit by the amount of available water stored in the root zone. The magnitude of difference in the deficit totals derived by using potential vs. calculated actual evapotranspiration would, of course, vary with the rooting depth of plants and the available water storage capacity of the soil. The first increments of the moisture surplus would similarly be attributed to soil moisture recharge up to the storage capacity of the particular soils under consideration. The amount of the moisture surplus contributing to runoff, ground water, or watershed moisture yield would be only that portion in excess of soil storage capacity. The soil moisture storage phase of the Thornthwaite-Mather "Water Balance" procedure was omitted in this study for the following reasons: Firstly, the time available did not allow the completion of that phase of the procedure. Several sets of data, for various assumed levels of soil moisture storage, would be required for each of the 209 weather stations. Secondly, it was thought that orientation of the study to soil moisture supply-plant growth relations, by including the soil moisture-plant use data, might tend to conceal information useful for other applications of the data. Users of these data must be reminded that soil moisture storage data are essential for certain types of studies of the moisture factor of climate. IV. Need for Evaporation and Transpiration Data Quantitative measures or estimates of evaporation and transpiration are essential in attempts to evaluate the moisture factor of climate for many purposes. Thornthwaite and Mather (19, p. 9) state "We know reasonably well how rainfall varies from one place to another over the inhabited parts of the earth and also how it varies through the years and from one year to another. On the other hand, few actual observations of the water movement from the earth to the atmosphere have been obtained and consequently we know next to nothing about the distribution of evapotranspiration in space and time." Workers in various scientific and applied fields have recognized numerous uses for quantitative values for evaporation, transpiration and evapotranspiration. As a consequence considerable attention has been directed to the evaluation of these moisture factors in recent years. In spite of recent emphasis the number of actual measurements, both in terms of time and geographical coverage, is limited and will probably remain limited for some time. Acquiring measured data for many locations and over extended periods is a tremendous task fraught with many difficulties of procedure, instrumentation, experimental controls, etc. Because of limited data, numerous empirical formulas have been proposed for "estimating" evapotranspiration. No attempt has been made to review the extensive literature dealing with the theoretical assumptions, uses, limitations, and other aspects of the many empirical methods in this report. A paper by van Bevel (22) presents a brief review of some of the methods and Lofgren (18) presents comparative results by various procedures for the Corvallis, Oregon,area.

9 -7- V. Reasons for Selecting the Thornthwaite-Mather Procedure The Thornthwaite-Mather procedure is one of several empirical methods for estimating evapotranspiration. Because of complexities of the factors influencing evapotranspiration it seems probable that no one empirical method will give values that are greatly superior to all others; no method will give values that are in complete agreement with actual measured values. Among the practical factors in the selection of an empirical method are the kinds of data and time required for computations. The Thornthwaite-Mather method was selected for this study for several very practical reasons as follows: 1. The required climatic data are available in standard summaries for many weather stations in Oregon. 2. The procedure is simple and rapid. 3. The results are in simple, direct, easily understood terms. 4. The data can be adapted to a wide range of uses. VI. Assumptions of the Thornthwaite-Mather Procedure and Value and Limitations of the Data The present Thornthwaite-Mather procedure has been developed from work begun by Thornthwaite more than 30 years ago. The history of the procedure is referred to in the "Water Balance" (19). The method assumes that with complete vegetative cover the evaporation and transpiration from an area will be controlled primarily by 1) the temperature of the atmosphere; 2) day length, as an index of solar radiation; and 3) the water content of the soil. The formula fails to take into account the direct effects of 1) humidity of the atmosphere; 2) wind and air eurbulence;3) cloudiness as a factor modifying solar radiation; and 4) other factors. Thornthwaite and Mather state (19), p. 15),"That satisfactory results could be obtained without the use of wind, humidity of solar radiation seems to be due to the fact that all of these important influences on evaporation including temperature vary together." That Thornthwaite and Mather recognize a need for further improvements in their formulas and procedure is suggested by the following statements: "The problem of developing a formula for potential evapotranspiration remains unsolved" ( 19, P. 18) and "The present report on the water balance should be considered as provisional and introductory. It is expected that as more scientists become aware of this research tool and begin to investigate it in detail as they apply it to different research problems there will be considerable improvement in the bookkeeping procedure to make it more rational and yet simpler to apply" (19, p. 76). Numerous investigators have pointed out inadequacies of the Thornthwaite or Thornthwaite-Mather formulas and procedures and various modifications have been proposed. Following is a statement by van Bavel (22, p. 13): "The formula of

10 -8- Thornthwaite is based on experience with watersheds in the central and eastern United States and has limited value. Where temperature and radiation are strongly correlated such as in temperate, continental climates the formula will work well. In southern latitudes or in maritime climates the formula does not seem to apply nearly as well. Further, the formula "lags" three or four weeks in the spring and summer because air temperature lags behind radiation, which really determines evapotranspiration." The following statement by Thornthwaite and Mather (19, p. 74) summarizes their experience in various applications of the method: "Checks on the validity of the results which are possible have shown that quite reasonable values for soil moisture, moisture deficit and moisture surplus have resulted from use of the procedure." Studies by Lofgren (18), the comments of van Bavel (22, p. 13) and other considerations suggest that values for potential evapotranspiration, derived by the Thornthwaite-Mather procedure, will probably be somewhat lower than measured values in an area with a climate such as that in Oregon. Values for consumptive use of water by different crops, derived by the Blaney-Criddle method, have been reported by Tileston and Wolfe (21) and are generally higher than the evapotranspiration values predicted in this study. Tileston and Wolfe also predict irrigation requirements for different areas of Oregon based upon expected irrigation efficiencies and average rainfall during the growing season. VII. Potential vs. Actual Evapotranspiration By definition, potential evapotranspiration is an expression of moisture losses, by evaporation and transpiration, from a completely vegetated area with soils at an optimum moisture content for plant growth. Thornthwaite and Mather (19, p. 10) and other investigators have recognized that loss of moisture from vegetated soils, by evaporation and transpiration declines with a decline in the moisture content of the soil. In other words "actual" evapotranspiration is lower than "potential" evapotranspiration when the soil moisture content falls below the optimum for plant needs. The rate of water loss declines progressively, but not necessarily in direct proportion, to the loss of moisture from the soil. Actual evapotranspiration refers to the actual rates of water loss from vegetated areas under the prevailing conditions of soil moisture and other pertinent factors at a particular time and place. Actual evapotranspiration, rather than potential evapotranspiration, determines the rate of moisture losses at soil moisture contents below the optimum for plant growth. For this reason the soil moisture available for plant growth will not be entirely dissipated when loss rates as calculated from potential evapotranspiration indicate that stored soil moisture is at zero. The plant growth sustaining capacity of a given quantity of soil moisture is therefore, greater than is suggested by potential evapotranspiration loss rates.

11 -9- VIII. Cautions in the Interpretation and Use of Water Balance Data The measured precipitation may not be a correct index of the amount of water that reaches and enters the soil for all sites in a particular landscape. Some sites will be drier than average because of losses of rainfall water as runoff, losses of snow melt water by runoff, losses through wind movement of snow, interception kof rainfall or snow by vegetation and for other reasons. Other sites may be moister than average because of "runon", subsurface additions, subsurface watertables, or from concentrations of snow from other areas. Variation in the water retentive capacities of soils may be a local factor of great importance in modifying the effective dryness or moistness of different landscape sites. Evapotranspiration also varies with conditions in a local landscape. Any condition that tends to modify temperatures, solar radiation, air movement or humidity will modify these values. Some of the important local factors that would modify evapotranspiration are position on the landscape, slope, aspect, exposure, and characteristics of the vegetative cover. Two examples will illustrate the importance of recognizing certain local conditions in using and applying water balance data. Example one: The soil site in the so-called "wet meadow" area near Burns, Oregon, is moister than is suggested from precipitation data for that area because of substantial amounts of "runon" from outside the immediate area. A similar situation may prevail on areas of runon in any local landscape. Example two: Appreciable runoff of rainfall or snow melt water may take place in certain localized areas in the Columbia Basin as a consequence of frozen soil conditions. These sites are obviously drier than is suggested by the precipitation records for the area. Influences of vegetative cover on evapotranspiration warrants some attention. Evapotranspiration values apply only to surfaces that are completely covered by vegetation. Potential evapotranspiration values are not a direct index of water losses by evaporation from bare soil surfaces and should not. be used as an index of moisture losses during bare fallow periods, on recently burned or cutover areas, or from other areas that are not supporting a complete vegetative cover or canopy. IX. Some Applications and Implications of the Data Application and interpretation of these basic climatic data is. not the objective of this study. Nevertheless, a listing of some possible applications and uses seems in order. It is considered that the data may be of limited to considerable usefulness for the following purposes: 1. General characterization of the temperature and moisture factors for: a. specific weather stations b. the major soil or land resource areas of Oregon

12 -1.0- c. other geographical divisions in Oregon d. ecological plant communities e. plant species selection and for various purposes in studying plant growth 2. Hydrologic and related studies. Identifying the "normal" water surpluses and deficit periods and estimating the average amounts of surpluses and deficits for studies of: surface and groundwater runoff, stream flow, groundwater recharge, reservoir storage capacity, needs, etc. 3. Estimating soil moisture recharge by precipitation. 4. Estimating the adequacy of stored soil moisture for plant growth in deficit periods. (Soil moisture storage capacities, depths of rooting of plants and water requirement periods of plants must be considered in making these estimates.) 5. Evaluating the summer fallow practice as a soil water storage technique in dryland farming. (Estimates under bare fallow conditions cannot be made directly from these data.) 6. Estimating water requirements for irrigation. 7. Estimating the water erosion hazard and for some phases of water erosion control planning. 8. Estimating water surpluses as a factor in drainage system planning. 9. Evaluating certain influences of the present climate in soil development. 10. Estimating the intensity of leaching losses of soil nutrients. kl. Estimating certain biological implications of atmosphere temperatures. 12. Estimating crop adaption and total heat energy available for plant growth from potential evapotranspiration and frost-free season data. A graphic presentation may be useful in making certain interpretations, applications or comparisons of the data. An example is presented in figure 1. This figure shows the seasonal relationship of average monthly precipitation and estimated potential evapotranspiration with periods and amounts of moisture surpluses and deficits for four stations with contrasting climates. The graphs illustrate the nature of the water balance data presented in the tables in the appendix. These graphs permit a ready comparison of the data from different climatic regions, for example, the perhumid Oregon coastal area with cool summers and mild winters (Tillamook) in contrast to the arid southeast region of Oregon with warm summers and cold winters (Owyhee Dam). Another comparison of interest can be made between the Willamette Valley (Albany) and the eastern portion of the Columbia Basin (Pendleton), both important agricultural areas of Oregon.

13 ,a2 II ;Io is Albany, Linn County Total surp Total def Pendleton Field Station Umatilla County Total surp. 7.0 Total def Ave. precipitation moisture surplus x- -x Ave. potential evap. moisture deficit Tillamook, Tillamook County Total surp ` 13 Total def Owyhee Dam, Malheur County - Total surp Total def a 4- a C N. 0 imilli JFMAMJJASONDJ JFMAMJJ ASONDJ Figure 1. Average precipation and average potential evapotranspiration for four selected locations.

14 -12- Appendix 1A. Index to Data Tables by Counties County County Table No. Page No. No. 1 Baker 1 through Benton Clackamas 10 through Clatsop 18 through Columbia 23 through Coos 27 through Crook 34 through Curry 36 through Deschutes 41 through Douglas 46 through Gilliam 54 through Grant 59 through Harney 68 through Hood River 79 through Jackson 82 through Jefferson 94 through Josephine 93, 99 through Klamath 104 through Lake 119 through Lane 129 through Lincoln 137 through Linn 140 through Malheur 142 through Marion 157 through Morrow 161 through Multnomah 163 through Polk 165 through Sherman 170 through Tillamook 174 through Umatilla 177 through Union 190 through Wallowa 195 through Wasco 198 through Washington 206 through Wheeler 208 through Yamhill 211 through

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19 -17- Appendix 3. Tables for Individual Weather Stations Key to Symbols in Data Tables Temperature Data ( F): (degrees Fahrenheit) Ave Max = Average daily maximum temperature Ave Min = Average daily minimum temperature Ave = Average daily temperature Precipitation and Water Balance Data: Ave P = Average precipitation Ave PE = Average potential evapotranspiration Surplus P-PE = precipitation minus potential evapotranspiration: average moisture surplus Deficit PE-P = potential evapotranspiration minus precipitation average moisture deficit Cum Surplus = Average cumulative moisture surplus Cum Deficit = Average cumulative moisture deficit Frost Free Season Data Notes Ave FFS (32 ) = Average dates and days between average dates of last spring and first fall occurrence of 32 F temperature. Ave FFS (280 ) = Average dates and days between average dates of last spring and first fall occurrence of 28 F temperatures. PE of FFS (32 ), (28 ) = Average total potential evapotranspiration between dates of occurrence of the temperature minima indicated. 1. Sources of data are indicated by number in the headings of the various columns and after days in the FFS data, e.g., Ave Max4. The 4 refers to listing number 4 in the bibliography. 2. Discontinuous record periods are indicated by "dis" following the record period.

20 Baker CAA Airport Baker County -18- Long ' W Lat ' N Elev ft. Table 1 - _ Calendar Ave Period Max 5 Ave Av Ave Surplus Deficit Cum Cum Min _. PE P - PE PE - P Surplus Deficit Jan Feb Mar April May June July Aug Sept Oct Nov Dec Annual Record 9 yrs 9 yrs 9 yrs Ave FFS (320)* Ave FFS (280)* PE of FFS (32 ) se PE of FFS (28 ) am Baker Station Long ' W Baker County Lat ' or 44 47' N Elev ft. Table 2 Temperature Data* Precipitation and Water Balance Data* Calendar Ave Ave Ave Ave Surplus Deficit Cum Cum Period Max3 Min' Ave3 P3 PE P - PE PE - - Surplus Deficit Jan Feb Mar April 55,7 33, May June July Aug Sept Oct Nov Dec. 3A _ q Annual. i I :. Record 40 yrs 40 yrs 40 yrs Ave FFS (320)* 5/22 to 9/23; 124 day s4 Ave FFS (28 )* 4/27 to 10/5; 161 days2 PE of FS (32 ) is 15.8 PE of FFS (28 ) s 18.8

21 Halfway Station Baker County Table Long ' W to ' W Lat ' N to 44 53' N Elev.2600 to 2675 ft. o _ Calendar Av Ayes Ay% Ave Surplus'Deficit Cum Cum 5 Period Mai Min Ave PJ PE P - PE PE - P Surplus Deficit Jan Feb Mar April May June July Aug Sept Oct Nov Dec _ _ Annual Record 10 yrs 10 yrs 10 yrs dis. Ave FFS (320)* Ave FFS (280)* PE of FFS (32 ) ei PE of FFS (28 ) m. Huntington Station Baker County Long ' W Lat ' N Elev ft Calendar Ave Period Max 5 Ave Min Ave 2 Ave2 Ave Surplus Deficit Cum Cum. P PE P - PE PE - P Surplus Deficit Jan Feb Mar , April May June July Aug Sept Oct Nov Dec ,7 0, Annual, 1 0 i Record 20 yrs 20 yrs , i Ave FFS 32 0)* 4/29 to 10/16; 170 days15 Ave FFS 28 * 4 4 to da a15 PE of FS 32 0 In 25.8 PE of FFS 28

22 Richland Station Baker County Table Long ' W to ' W Lat ' N to 44 48' N Elev to 2350 ft. Calendar Ave Ave Ave Ave Surplus Deficit Cum Cum Period. Max 3 Min 3 Ave 3 P 3 PE P - PE PE - P Sur plus Deficit. Jan... 4 vs..1 Feb Mar April May June July Aug Sept Oct Nov Dec Annual Record 26 yrs 26 yrs 27 yrs dis. Ave FFS (320)* 5/15 to 9/18; 126 days15 PE of FFS (320) ss 17.7 Ave FFS (28 0)* 5/1 to 9/28; 150 days15 PE of FFS (28 ) 20.4 Sparta Station Baker County Long ' W Lat ' N Elev ft. Table Temperature Data* Precipitation and Water Balance Data* Calendar Ave Ave Ave Ave Surplus Deficit Cum Cum Period Max 3 Min 3 Ave 3 P 3 PE P - PE PE - P Surplus Deficit Jan Feb Mar April May June July Aug Sept Oct Nov Dec Annual Record 34 yrs 34 yrs 35 yrs dis Ave FFS (320)* Ave FFS (28 )*,PE of FFS (32 0) 0, PE of FFS (28 ).0

23 Unity Station Baker County Long ' W Lat ' N Elev ft., Calendar Ave Ave Ave Ave Surplus Deficit Cum Cum Period Max 5 Min 5 Ave 5 P PE P - PE,PE - P Surplus Deficit Jan Feb Mar April May June July Aug :8 Sept Oct Nov Dec. 35,1 _ Annual 513,1 _28.0 k, 10.8, Record 12 yrs 11 yrs 11 yrs Ave FFS (320)* Ave FFS (280)* % dis. PE of = PE of FFS (28 ) Alpine Station Benton County Long ' W Lat ' N Elev. 400 ft... V A.,.... Calendar Ave, Ave Ave Period Max' Min4 Ave4 P 4 Ave Surplus Deficit Cum Cum PE P - PE PE - P Surplus Deficit Jan Feb Mar , 34.5 April May June July Aug Sept Oct Nov Dec Annual ,0, Record 16 yrs 16 yrs 15 yrs Ave FFS (320)* Ave FFS (28 )*.. o = PE of FFS (28 )