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.    

&&

.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.   

&&

.BOI WATCHES/WARNINGS/ADVISORIES...
ID...NONE.
OR...NONE.
&&

$$

WEATHER.GOV/BOISE

SHORT TERM...JT
LONG TERM....GS
AVIATION.....GS