AREA FORECAST DISCUSSION

 
 FXUS65 KBOI 241033 CCA
 AFDBOI
 
 AREA FORECAST DISCUSSION...CORRECTED
 NATIONAL WEATHER SERVICE BOISE ID
 240 AM MST TUE NOV 24 2009
 
 .SHORT TERM...TODAY THROUGH WEDNESDAY...LIGHT NORTHWEST FLOW ALOFT 
 IS OVER OUR AREA TODAY AHEAD OF A BUILDING UPPER LEVEL RIDGE. WE ARE 
 SEEING THE START OF A TEMPERATURE INVERSION WHICH WILL INTENSIFY 
 TONIGHT AND WEDNESDAY. EARLY THIS MORNING MID LEVEL AND HIGH CLOUDS 
 ASSOCIATED WITH A WEAK SHORTWAVE ARE APPROACHING FROM WESTERN AND 
 CENTRAL OREGON. THESE CLOUDS WILL PARTIALLY DISSIPATE CROSSING THE 
 DEVELOPING RIDGE AXIS AND NO PRECIPITATION IS EXPECTED...BUT THERE 
 WILL BE ENOUGH SHADING...COMBINED WITH THE INVERSION AND LIGHT 
 SURFACE WINDS...TO HOLD TEMPERATURES BACK. SO HIGHS SHOULD BE A FEW 
 DEGREES BELOW YESTERDAY/S. THE RIDGE...ALONG WITH THE INVERSION... 
 WILL REACH  MAXIMUM DEVELOPMENT WEDNESDAY AFTERNOON. THE COMBINATION 
 OF MORE SUN AND A BETTER DOWN VALLEY PRESSURE GRADIENT SHOULD 
 BALANCE THE DEEPER INVERSION...SO WE EXPECT HIGH TEMPERATURES 
 WEDNESDAY WILL BE CLOSE TO TODAY/S.  WE ARE KEEPING PATCHY VALLEY 
 FOG AND STRATUS FOR LATE TONIGHT AND WEDNESDAY MORNING...BUT WITH 
 THE DRY AIRMASS CONFIDENCE IS RATHER LOW. 
 
 .LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY...UPPER RIDGE BUILDS 
 OVER THE AREA WEDNESDAY NIGHT AND EARLY THURSDAY IN ADVANCE OF NEXT 
 PACIFIC SHORT WAVE. DURING THANKSGIVING DAY...RIDGE AXIS MOVES EAST 
 TO WYOMING AND MONTANA ALLOWING A SOUTHWEST FLOW OF WARMER AND DRY 
 AIR INTO THE REGION. EXTENDED MODELS IN GOOD AGREEMENT IN THIS TIME 
 RANGE BUT WILD CARD AT THIS TIME IS STRENGTH OF ASSOCIATED INVERSION 
 AND THE POSSIBILITY OF LOW CLOUDS AND FOG. FEELING IS THAT SINCE WE 
 HAVE BEEN QUITE DRY THIS MONTH AND ESPECIALLY RECENTLY..LOW CLOUD 
 INVERSION CONDITIONS MAY NOT SET UP YET. THIS MAY LEAD TO A QUITE 
 MILD...BREEZY AND DRY DAY FOR THANKSGIVING AND THIS IS WHAT WE HAVE 
 FORECAST. A PACIFIC SHORT WAVE MOVES ACROSS THE AREA FRIDAY AND 
 FRIDAY NIGHT FOR LIGHT AMOUNTS OF PRECIPITATION WITH SYSTEM ONCE 
 AGAIN EMBEDDED WITHIN A FAST PROGRESSIVE FLOW. BY SUNDAY...MODELS 
 AGREE WITH HIGH AMPLITUDE RIDGE REBUILDING OVER THE PACIFIC 
 NORTHWEST WHICH REMAINS THROUGH THE LAST DAY IN NOVEMBER. 
 TEMPERATURES AT SEASONAL VALUES THROUGH THE PERIOD BUT PRECIP LOOKS 
 TO BE BELOW NORMAL.          
 
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 .AVIATION...VFR CONDITIONS. LIGHT WINDS SURFACE AND ALOFT WITHIN 
 HIGH PRESSURE CENTER. LOW CLOUDS PRESENTLY IN THE UPPER SNAKE VALLEY 
 MAY DEVELOP WESTWARD THIS MORNING TOWARD THE KJER AND KTWF AS EAST 
 FLOW STRENGTHENS. ELSEWHERE...EXTENSIVE MID CLOUD SPREADING OVER THE 
 AREA FROM CENTRAL OREGON THIS MORNING...BUT DECREASING THIS 
 AFTERNOON AS WEAK WAVE MOVES EAST UNDER RIDGE. VISIBILITY 
 UNRESTRICTED BUT REDUCING TO 5-7SM IN HAZE AS HIGH PRESSURE 
 STAGNATES AND INVERSION INCREASES TONIGHT.  
 
 &&
 
 .BOI WATCHES/WARNINGS/ADVISORIES...
 ID...NONE.
 OR...NONE.
 &&
 
 $$
 
 WEATHER.GOV/BOISE
 
 SHORT TERM...JT
 LONG TERM....GS
 AVIATION.....GS