, QC 995 . U61 no. 56 c . 2 F ;hnical Memorandum NWS CR-56 THE PREDICTION OF DAILY DRYING RATES Jerry D. Hill WSO/AG Lexington, Kentucky Scientific Services Division Central Region Headquarters November 1974 NATIONAL OCEANIC AND National Weather noaa ATMOSPHERIC ADMINISTRATION Service I NOW TFCHNICAL MEMORANDA National Weathar Service, Central Region 6ubaarlea r> w„.hBr Service Central Region (CR) sube.rl.e provldea an Infernal medium for the documentation and quick dl.e.minatlon The National Weather^Servlcetentr ^ for publication. n,e eerie. la uaed to report on work In progress, to deacrlbe * h*?U«l,nroredurra and practices or to relate progr.se to a limited audience. Thoae Technical Memoranda will report on lnvestlga- ufn? IwX .f mainly to regional p.rconn.1. a^ hence will not be widely dlatribuUd. Pane re 1 to 11 are In the former aeries. ES5A Technical Memoranda, Central Region Technical Memoranda (CRTH); papers 16 to 36 are ln^the former^serles, FSSA Technical Memoranda, Weather Bureau Technical Memoranda (WBTM). Beginning with 37, the papers are now part of the aeries, NOAA Technical Memoranda NWS. Papers that have a FB or COM number are available from the National Technical Information Service, U. S. Department of Connerce, ►JjL Prt»-t RovaI Rond SDrinrfield Va. 22151. Price: $3.00 piper copy; $0.95 microfiches Order by Accession number shown in parenthe9ls°at end of each entry.’ All other papers are available from the National Weather Service Central Region, Scientific Service* Division, Room 1836, 601 E. 12th Strest, Kansas City, Mo. 66106. ESSA Technical Memoranda Precipitation Probability Forecaat Verification Sunmary Nov. 1965-Mar. 1966. OSD Staff, WDCRH - May 1966 CPTM 1 A Study of Summer Showers Over the Colorado Mountains. Wm. C. Sullivan and James 0. oeveraon - Juno 1966 CRTM 2 Areal Shower Distribution - Mountain Versus Vallsy Coveraga. Ms. C. Sullivan and James 0. ...verson - June 1966 CPTM 3 Heavy Rains In Colorado June 16 and 17, 1965. SSD Staff, WBCRH - July 1966 CPTM u The Plum Fire. Wm. C. Sullivan - August 1966 her 10AA CPTM 5 Precipitation Probability Forecast Verification ouimapy Nov. 1965-July 1966. SoD Staff, WBCRH - Septaaber 1966 CPTM 6 7.rfeet of Diurnal V.'eather Variations on Soybean Harvest Efficiency. Leonard P. Hand - October i960 CRTM 7 Climatic Frequency of Precipitation at Central Region Stations. SSD Staff, WBCRH - November 1966 CRTM 8 Heavy Snow or dailng. Harry W. Haldheuser - December 1966 CPTM 9 Detection of a Weak Front by VSR-57 Radar. Harry W. Waldheuser - December 1966 CRTM 10 Public Probability Forecasts. SSD Staff, WBCRH - January 1967 CPTM 11 Heavy Snow Forecasting In the Central United States (An Interim Report). SSD Staff - January 1967 CK7M 12 Diurnal Surface Ceostrophic Wind Variations Over the Great Plains. Wayne E. Songster - March 1967 CPTM 13 Forecasting Probability of Summertime Precipitation at Denver. Wm. G. Sullivan and James 0. Severson - March 1767 CRTM 14 Improving Precipitation Probability Forecasts Using the Central Region Verification Printout. Uwrenoe A. Hughes - May 1967 CRTM 15 Small-Scale Circulations Associated With Rallatlonal Cooling. Jack R. Cooley - June 1967 WBTM CR 16 Probability Verification Results (6-Month and 18-Month). Lawrence A. Hughes - June 1967 CR 17 V/BTM On the Use and Misuse of the Drier Verification Score. Lawrence A. Hughes - August 1967 (PB 175 771) WBTM CP 18 Probability Verification Resulta (24 Months). Lawrence A. Hughes - February 1968 V/BTM CP 19 Radar Depiction of the Topeka Tornado. Norman E. Prosser - April 1968 WITH l CP 20 WDTM CR 21 Wind Waves on the Great Lakes. Lawrence A. Hughes - May 1968 ism /pb isi Tit) Seasonal Aspects of Probability Forecasts: 1. Summer. Lawrence A Hughe. - June 1968 (PB 185 733) wn*m CR 22 Seasonal Aspects of Probability Forecasts: 2. Fall. Lawrence A. Hughss - September 1968 (PB 185 734) 104, WBTM CR 23 The Importance of Areal Coverar. In Precipitation Probability Forecasting. John T. Curran and Uwr.no. A. Hughes ‘ ‘‘•Pj V/BTM CR 24 Meteorological Conditions ae Related to Air Pollution Chicago, Illinois, April ^ Sw*n 0c‘°b#r WBTM CR 25 Seasonal Aepecta of Probability Forecasts: 3. Wlnlsr. Lawrence A. ughe. - December 1968 PD 185 735) WBTM CR 26 Seasonal AflDfcta of Probability Forecast.: 4. Spring. Lawrence A. Hughes - February 1969 JPB 185 736# WBTJt CR 27 Minimum Tem^rature Foreca.ting During Poeeible Fro.t Periods at Agricultural Weather Station, in Weatcm Michigan. WBTM CR 28 torn hall A. Goderberg - torch 1969 . u . 1QAo An Aid for Tornado Warnings. Harry W. Waldheuser and Lawrence A. Hughes - V/BTM CR 29 *VT±1 1969 An Aid in Forecasting Significant Lake Snows. H. J. Rothrock - November 1969 VBTM CR 30 A Forecast Aid for Boulder Winds. Wayne E. Sangster - February 1970 1<y70 WBTM CR 31 An Objective Method for Estimating the Probability of Severe Thunders toms. Clarence L. David - February 1970 VBTM CR 32 Kentucky Air-Soil Temperature Climatology. Clyde B. Lee - February 1970 V/BTM CR 33 Fffective Use of Mon-Structural Methods in Water Management. Verne Alexander - March 1970 WBTM CR 34 A Note on the Categorical Verification of Probability Forecasts. Uwrence A. Hughe, and Wayne E. Sang.Ur - August 1970 .V/BTM CR 35 A Comparison of Observed and Calculated Urban Mixing Depths. Donald E. Wuerch - August 1970 WBTM CR 36 NOAA Technical Memoranda NWS Forecasting Maximum and Minimum .Surface Temperatures at Topeka, Kansas, Using Guidance from the PE .Numerical Prediction NWS CR 37 Model (FOUS). Morrie S. Webb - November 1970 (COM-71-OOH8) Snow Forecasting Tor Southeastern Wisconsin. Rheinhart W. Harms - November 1970 {COM-71-00019) _ - b (COM-73l-C0369) NWS CR 38 A Synoptic Climatology of Bli«arda on the North-Central I lain, of JU:. United State^. E. toukTib 1971 (COM 71-00369) NWS CR 39 Forecasting the Spring 1969 Kldweat Snowmelt Flood.. Herman F. Hondecheln - Ttbr^rj im (C0H-71-00489) CR 40 NWS The Temperature Cycle or Lake Michigan 1.(Spring and Summer). Lawrence A. Hughee - April 1971 (COH-71-00545) NWS CR a Du*t Devil Meteorology. Jack R. Cooley - Hay 1971 (COM-71-00628) CR 42 NWS Sumner Shower Probability in Colorado as Related to Altitude. Alois G. Topil - toy1971 (c0M NWS CR 43 An Investigation of the Resultant Transport Wind Within the Urban Complex. ,h™ iSiaaAV6 . NWS CR 44 The Relationship of Some Cirrus Formation, to Sevsre Local Storms. William E. Williams - Juljr 1971 (C*"71"O08W( COM-71-01039 / MS CR 45 Ths Temoerature Cycle of lake Michigan 2. (Fall and Winter). Lawrence A. Hugh*. - September 1971 (X—VXUJ7/ MS CR 46 Practical Application of a Graphical Method of Geoetrophlc Wind Determination. C. B. Johneon - November 1971 NWS CR 47 (COM-71-01084) ‘ (Continued on back inside cover) 00 tllf NOAA Technical Memorandum NWS CR-56 THE PREDICTION OF DAILY DRYING RATES Jerry D. Jmi WSO/AG Lexington, Kentucky Scientific Services Division Central Region Headquarters November 1974 ATMOSPHERIC suit library FEB 2 7 1- N.O.A.* U. S. Dept. oJ UNITED STATES NATIONAL OCEANIC AND National Weather DEPARTMENT OF COMMERCE ATMOSPHERIC ADMINISTRATION Service F Frederick B. Dent, Secretary Robert M. White, Administrator George P. Cressman, Director To THE PREDICTION OF DAILY DRYING RATES Jerry D. Hill National Weather Service WSO/AG Lexington, Kentucky ABSTRACT Weather observations on 92 rain-free days were used to develop a relation­ ship between open-pan evaporation and various meteorological parameters. A regression analysis determined that 86% of the variance in total daily evaporation could be explained using maximum saturation vapor pressure deficit, average daytime wind speed, and total solar radiation. Predictions obtained using the regression equation have an average absolute error of . 02 inches/day as compared to an average absolute error of . 038 inches/ day when Penman's equation was used. A simple nomogram is presented so that forecasts of wind speed, radiation, maximum temperature, and minimum relative humidity can be used to solve the regression equation graphically for total daily evaporation and categorical drying conditions. I. INTRODUCTION One of the most observable effects of the weather at any location is the dry­ ing rate or the power of the air to remove water by direct evaporation. While this effect is of interest to nearly everyone, it is probably one of the least understood of all items which confront the meteorologist. Whether it be the housewife wanting to know how well her laundry will dry, the far­ mer wanting to know how soon his fields will dry, or the football coach wanting to know if his playing field will dry before tonight's game, there is a universal need for drying forecasts. Because of the difficulty in pre­ paring evaporation predictions though and possibly the difficulty in express­ ing them to the public, such forecasts have only been prepared as part of very limited programs in the Weather Service. Unlike precipitation which is highly dependent upon 3-dimensional models of the atmosphere, evaporation takes place near the surface and is dependent primarily on the meteorological factors only at that level. Since there is considerable local variation in these meteorological factors due to influences of shade, sheltering, etc. , it is not unusual to find considerable local varia­ tion in daily drying. Generally, however, well-exposed sites should exhibit uniform day-to-day variation in drying representative of the varying weather conditions. The basic meteorological observation related to drying conditions is open- pan evaporation. The pan, which is made of metal, has standard dimensions consisting of a four-foot diameter and 10 inch depth. It is usually mounted on a slatted wooden frame to hold it slightly above the ground and prevent the conduction of heat from the soil into the pan.