AREA FORECAST DISCUSSION

 
 FXUS65 KBOI 250953
 AFDBOI
 
 AREA FORECAST DISCUSSION
 NATIONAL WEATHER SERVICE BOISE ID
 253 AM MST WED NOV 25 2009
 
 .SHORT TERM...TODAY THROUGH THANKSGIVING...BOTH THE UPPER LEVEL 
 RIDGE AND THE INVERSION INDEX MAX OUT OVER OUR AREA TODAY. THE 
 SURFACE HIGH PRESSURE CENTER STAYS ANCHORED OVER EASTERN IDAHO 
 THROUGH THURSDAY. THE GRADIENT STRENGTHENS ACROSS SOUTHWEST IDAHO 
 AND SOUTHEAST OREGON THURSDAY AFTERNOON...PROVIDING BETTER DOWN 
 VALLEY FLOW. THIS...COMBINED WITH A STEADILY DECREASING INVERSION 
 INDEX...WILL RESULT IN SLIGHTLY WARMER AFTERNOON TEMPERATURES.   
 SKIES WILL STAY MOSTLY CLEAR THROUGH TONIGHT...THEN HIGH CLOUDS WILL 
 INCREASE FROM THE WEST ON THURSDAY AS THE NEXT PACIFIC WEATHER 
 SYSTEM MOVES ONSHORE. 
 
 .LONG TERM...THURSDAY NIGHT THROUGH WEDNESDAY...APPROACHING PACIFIC 
 SHORTWAVE WILL MOVE THROUGH THE REGION ON FRIDAY WITH VALLEY RAIN 
 AND MTN SNOW. LATEST MODEL QPF AMOUNTS ARE LIGHT WITH BAND OF HIGHER 
 PW GETTING CUT OFF AS SHORTWAVE MOVES ONSHORE. OVERALL PATTERN STAYS 
 PROGRESSIVE SO PRECIP NOT EXPECTED TO LINGER AND THUS SHOULD BE 
 LIGHT. A STRONGER RIDGE WITH MORE AMPLITUDE DEVELOPS OFFSHORE DURING 
 SATURDAY...BUT A SURGE OF MOISTURE COMES SOUTHEAST THROUGH THE AREA 
 SATURDAY AND SATURDAY NIGHT BEFORE THE RIDGE CRESTS IN. THIS MAY BE 
 THE LAST CHANCE FOR MEASURABLE RAIN OR SNOW IN NOVEMBER IN WHAT HAS 
 BEEN A DRY MONTH. DEPENDING ON HOW MUCH RAIN OR SNOW FALLS OVER THE 
 WEEKEND...THIS WILL ALSO HAVE IMPLICATIONS FOR INVERSION DEVELOPMENT 
 ALONG WITH LOW CLOUDS AND FOG IN A STRONGER RIDGE PATTERN SETTING UP 
 EARLY NEXT WEEK.    
 
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 .AVIATION...VFR TODAY AND TONIGHT...BUT STAGNATING CONDITIONS UNDER 
 A STRONG HIGH PRESSURE RIDGE BEGINNING TO HAVE AN EFFECT ON 
 VISIBILITY AND OVERALL AIR QUALITY. INVERSION AT ITS STRONGEST EARLY 
 THURSDAY AND THUS HAVE INDICATED WIDESPREAD HAZE OVER THE LOWER 
 VALLEYS. VSBY MAY REDUCE TO 5 TO 7SM IN HAZE THURSDAY BEFORE LOW 
 LEVEL EAST FLOW PICKS UP AHEAD OF APPROACHING PACIFIC SHORT WAVE. 
 SURFACE WINDS LIGHT TODAY AND TONIGHT WITH LIGHT WINDS ALOFT IN 
 CENTER OF UPPER RIDGE.   
 
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 .BOI WATCHES/WARNINGS/ADVISORIES...
 ID...NONE.
 OR...NONE.
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 WEATHER.GOV/BOISE
 
 SHORT TERM...JT
 LONG TERM....GS
 AVIATION.....GS