FXUS65 KPIH 100237
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
737 PM MST WED DEC 9 2009

.UPDATE...WILL LET THE WINTER WEATHER ADVISORY FOR THE CARIBOU
HIGHLANDS EXPIRE AT 8 PM THIS EVENING AS WINDS AND SNOW HAVE
DECREASED QUITE A BIT THIS EVENING. TEMPERATURES CONTINUE TO INCH
DOWNWARD TO NEAR OR BELOW ZERO. WINDS HAVE NOT INCREASED BUT SOME
AREAS REMAIN IN THE 5 TO 10 MPH RANGE. DUBOIS TO CAMP CREEK ON
INTERSTATE 15 IN PARTICULAR HAS EXTREME WIND CHILLS AROUND 20
BELOW...WHILE MOST AREAS ARE IN THE 10 TO 20 BELOW RANGE. SKIES
ARE STILL MOSTLY CLEAR EXCEPT AROUND ISLAND PARK AND REXBURG.
THERFORE...AM NOT IN A BIG HURRY TO CANCEL THE WIND CHILL
WARNING. RS

&&

.PREV DISCUSSION... /ISSUED 210 PM MST WED DEC 9 2009/ 

SHORT TERM...TONIGHT THROUGH FRIDAY.

SATELLITE SHOWS CLEARING STARTING TO TAKE PLACE OVER THE REGION.
UPPER LEVEL FLOW CONTINUES OUT OF THE NORTHWEST AND THERE IS STILL
PLENTY OF LOW LEVEL MOISTURE AROUND. AS A RESULT...EXPECT SNOW
SHOWERS TO REMAIN POSSIBLE OVER THE EASTERN HIGHLANDS TONIGHT DUE
TO UPSLOPE FLOW. ALSO EXPECT LOW STRATUS TO REDEVELOP OVER THE
SNAKE PLAIN LATER TONIGHT AS TEMPS PLUMMET AND THE MOISTURE IS
FORCED TO CONDENSE. WINDS WILL STAY UP TONIGHT...SO NOT EXPECTING
MUCH FOG. ALSO...WILL CONTINUE THE WINTER WEATHER ADVISORY FOR
THE CARIBOU HIGHLANDS DUE TO THE COMBINATION OF SNOW AND BLOWING
SNOW THIS EVENING. WILL CANCEL ELSEWHERE SINCE WEB CAMS ARENT
SHOWING MUCH. THE WINDS WILL CREATE ANOTHER PROBLEM AND THAT BEING
WIND CHILLS IN THE UPPER SNAKE VALLEY...EASTERN HIGHLANDS DOWN TO
BEAR LAKE. WIND CHILL VALUES COULD FALL TO BETWEEN -20 AND -30 IN
THESE AREAS BEFORE THE WINDS DIMINISH LATE TONIGHT. THEN...TRADE
OFF VERY COLD WIND CHILLS FOR VERY COLD TEMPERATURES. VERY COLD
WEATHER IS EXPECTED TO PERSIST THROUGH THE SHORT TERM AS ARCTIC
HIGH PRESSURE REMAINS IN CONTROL. ALTHOUGH...SHOULD SEE DRIER
WEATHER DUE TO THE HIGH PRESSURE.

LONG TERM...FRIDAY NIGHT THROUGH WEDNESDAY. MODELS REMAIN IN 
GENERAL AGREEMENT THROUGH THE PERIOD. ZONAL FLOW IN PLACE FOR THE 
WEEKEND WITH PACIFIC ENERGY BRINGING WET CONDITIONS BACK TO EASTERN 
IDAHO. WARM FRONTAL BOUNDARY WILL PRODUCE OVERRUNNING PERIODS OF 
SNOW OVER THE WEEKEND BEFORE THE MAIN LOW MOVES BY THROUGH SUNDAY 
EVENING.  HAVE INCREASE POPS TO REFLECT THIS.  WITH SLIGHTLY WARMER 
AIR DUE TO PACIFIC OCEAN ORIGINATION...HAVE KEPT PACE WITH IDEA OF 
MODERATED TEMPERATURES.  EXCELLENT AGREEMENT BETWEEN GFS ECMWF AND 
ENSEMBLES WITH RIDGE TRYING TO BUILD INTO WESTERN STATES BY MONDAY 
THOUGH MODELS CONTINUE TO SHOW LIGHT PRECIP ACCUMULATIONS WITH WEAK 
EMBEDDED STORM SYSTEMS MOVING THROUGH THE AREA IN NORTHWEST FLOW.   
HAVE LEFT POPS AT OR SLIGHTLY BELOW CLIMO FOR TUESDAY AND 
WEDNESDAY...HOWEVER NEED TO WATCH FOR INVERSIONS SETTING UP AS LARGE 
SCALE RIDGE DEVELOPS. PRESTON/DMH

AVIATION...UPPER SYSTEM CONTINUES TO ENHANCE AREAS OF MVFR TO IFR 
CONDITIONS IN UPPER SNAKE VALLEY THIS AFTERNOON AND EXPECT THIS TO 
CONTINUE UNTIL 00Z.  REST OF AREA HAS ISOLATED MVFR WITH MOSTLY VFR 
CONDITIONS.  DUE TO UPSLOPE FLOW OF AIR...EXPECT DECK OF CLOUDS TO 
REDEVELOP FOR IDA AND PIH LOCATIONS OVERNIGHT WITH DECENT POTENTIAL 
FOR IFR CONDITIONS BETWEEN 10Z AND 16Z TOMORROW. PRESTON

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WIND CHILL WARNING UNTIL 4 AM MST THURSDAY FOR IDZ019-020-023-
025.

WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR IDZ023.

&&

$$