IV. WIND 



V/ind forecasts will include direction and velocity with velocity given in miles 

 per hour, 



Modifying Terms Applied to V/ind Direction 



a) Variable - Irregular « Usually subject to sIovt or moderate changes of varying 

 magnitude • 



B) Changeable - Irregxilar changes of direction of a more decided nature and 

 magnitude than "variable", 



C) Mostly - A modifier used when winds will be subject to some variability, to 

 indicate viiat direction will predominate, 



V. HTO/HDITY OR DRYING CONDITIONS 



The drying rate is a fvinction of wind velocity, sunshine, temperature and rela- 

 tive humidity. The first three of these elements have already been covered, 

 and the forecaster ^7ill combine his forecast of these elemenlswith expected re- 

 lative humidity to evaluate the drying rate, Eiying coiditions will then be 

 forecast as being in one of the following classes; 



1, Poor drying: 2, Fair drying; 3, Good drying: It, Excellent drying, 



VI. FORECAST PERIOD 



A) " Today" covers today's daylight hours, if the forecast also mentions this 

 evening or tonight<i iJ'hen the latter tvfo are not mentioned, "today" covers 

 the period until midnight tonight, 



B) "Tonight" covers the hours of darkness, or from sunset to sunrise, 



C) "Evening" covers the p riod from about two hours before sunset to about two 

 hours after sunset, 



D) "Tomorrov/" covers the period from about sunrise to siinset the following day, 

 unless the night period is not mentioned. If the night period is not men- 

 tioned, "Tomorrow" begins from midnight tonight and ends at sunset tomorrow, 



E) "Forenoon" covers the period from about sunrise until noon, 



F) "Afternoon" covers the period from noon to sunset. 



Length of forecast period . The agricultural forecast ordinarily covers the 

 period of today and tomorrow. An outlook for the day after tomorrovf is given if 

 the current weather pattern is such that a forecast for the third day can be made 

 with reasonable assurance of verification. 



