FXUS65 KPIH 100925
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
225 AM MST THU DEC 10 2009

.SHORT TERM...TODAY THROUGH SATURDAY NIGHT. IT IS DEFINITELY COLD
OUT THERE THIS MORNING AS ADVERTISED. THE WINDS HAVE DIED OFF TO
10 MPH OR LESS PRETTY MUCH ACROSS ALL OF EASTERN IDAHO. ALTHOUGH
SOME SPOTS COULD STILL SEE WIND CHILLS AT -20 OR LOWER...THIS WILL
BE MAINLY DUE TO VERY COLD AIR TEMPS AND EVEN THE SLIGHTEST WIND
CREATING WIND CHILL. WE WILL CANCEL THE WIND CHILL WARNING WITH
THE MORNING FORECAST PACKAGE. THE STRATUS PROBLEM IS NOT REALLY
MUCH OF ONE RIGHT NOW. ANY STRATUS THAT HAS FORMED OR MAY FORM
EARLY THIS MORNING WILL REMAIN THE UPPER SNAKE PLAIN AND ADJACENT VALLEYS
OF THE UPPER SNAKE HIGHLANDS. IT WILL REMAIN COLD THIS AFTERNOON
EVEN WITH SOME WARMING ALOFT TAKING PLACE. HAVE WARMED UP THE MID
AND UPPER SLOPES TODAY...BUT KEPT MOST OF THE VALLEYS WITHIN A
COUPLE OF DEGREES OF WEDNESDAYS HIGHS DUE TO THE INVERSION AND THE
COLD START. ANY SNOW WILL BE LIGHT AND CONFINED TO THE MOUNTAINS
ALONG THE WYOMING BORDER...ESPECIALLY FARTHER NORTH. TONIGHT WILL
BE COLD ONCE AGAIN. ANY CLOUDS OTHER THAN STRATUS WILL BE CLOSER
TO THE MONTANA BORDER AND YELLOWSTONE. LOOKING AT THE STRATUS
POTENTIAL...THE MODELS DO SHOW IT REFORMING AGAIN AND SPREADING IT
DOWN THE VALLEY AS THE FLOW BECOMES DOWNVALLEY DOMINANT. THE MOST
LIKELY AREAS FOR STRATUS WILL ACROSS NORTHERN AND WESTERN PORTIONS
OF THE SNAKE PLAIN. TEMPERATURES WILL BE INTERESTING AS THE NAM
WANTS TO MAKE IT EVEN COLDER THAN THIS MORNING WHILE THE GFS
PUSHES LOWS UP A FEW DEGREES. THE FORECAST LEANS TOWARD THE GFS IN
THAT REGARD. WHERE THE DOWNVALLEY WINDS ARE A LITTLE
STRONGER...THE GFS WILL LIKELY PAN OUT. IT IS WHERE THE WINDS ARE
LIGHT AND NO CLOUD COVER IS PRESENT THAT IS WORRISOME...AND THE
MUCH COLDER NAM MAY BE THE WINNER AFTER ALL. THE DAY SHIFT WILL
DEFINITELY HAVE SOMETHING TO PONDER.

FOR TOMORROW...THE ANTICIPATED SHIFT FROM THE ARCTIC INFLUENCE TO
FLOW FROM THE PACIFIC WILL BE UNDERWAY. CLOUDS WILL BE INCREASING
FROM THE SOUTHWEST DURING THE AFTERNOON. TEMPERATURES WILL
CONTINUE TO WARM...ABOUT TEN DEGREES ON AVERAGE ACROSS THE
FORECAST AREA. THE VALLEYS WILL BE SLOWER TO WARM DUE TO LINGERING
INVERSIONS. FOR FRIDAY NIGHT AND SATURDAY...THE CHANCE OF SNOW
REALLY RAMPS UP. THE MAIN SYSTEM WILL REMAIN OFFSHORE...BUT A WEST
TO SOUTHWEST FLOW OPENS UP AND WILL TRANSPORT PACIFIC MOISTURE IN
THE WARM AIR ADVECTION PATTERN AHEAD OF IT. THE VALLEYS SHOULD
FINALLY MIX OUT BY LATER SATURDAY AND SEE TEMPERATURES AROUND
FREEZING. THE MOUNTAINS WILL SEE MOST OF THE SNOWFALL FOR THE END
OF THE SHORT TERM PERIOD...EXCEPT FOR SATURDAY NIGHT WHEN THERE
MAY BE A LITTLE MORE JET STREAM DYNAMICS AT PLAY VERSUS PURE
UPSLOPE/DOWNSLOPE FLOW. THIS WOULD HELP GIVE THE ENTIRE SNAKE
PLAIN A LITTLE BETTER CHANCE OF SEEING NEW SNOW. SINCE THIS IS A
WARMER AIR MASS...THE SNOW WILL BECOME SOMEWHAT WETTER ESPECIALLY
ON SATURDAY AFTERNOON. WINDS WILL RAMP UP AS WELL...SO THAT COULD
PLAY INTO SOME BLOWING AND DRIFTING SNOW FOR SOME AREAS. AS THE
PATTERN EVOLVES...WE WILL BE ABLE TO BETTER PINPOINT SNOW AMOUNTS
AND LOCATIONS OF THE HEAVIER SNOWFALL. WINTER WEATHER HIGHLIGHTS
MAY BE NEEDED FOR PORTIONS OF EASTERN IDAHO BY THE
WEEKEND...ESPECIALLY IN THE MOUNTAINS.  KEYES

.LONG TERM...GFS/ECMWF BOTH SHOWING MOIST PAC TROUGH SWEEPING EAST 
THROUGH REGION WHILE A BROAD CANADIAN TROUGH AMASSES ALONG THE NRN 
BORDER. BOTH MODELS HAVE SIMILAR PRECIPITATION DETAILS IN 
WEST-NORTHWEST FLOW WITH ENHANCED AREAS NEAR THE SAWTOOTH RANGE AND 
ERN HIGHLANDS THROUGH SUNDAY NIGHT. UPPER RIDGE BEGINS TO AMPLIFY 
ALONG THE PAC COAST IN RESPONSE TO A NRN PAC LOW SHIFTING INTO THE 
GULF OF ALASKA. BOTH THE ECMWF AND GFS SHOW PERIODIC WAVES OF 
MOISTURE TOPPING THE RIDGE AND SPILLING INTO THE REGION THROUGH 
TUESDAY. BEYOND TUESDAY...THE GFS TRENDS STRONGER WITH THE RIDGE AND 
CONSEQUENTLY DRIER WHILE THE ECMWF MAINTAINS A MOIST SW FLOW INTO 
THE PAC NW STATES WHICH WOULD LEAVE IDAHO OPEN TO OVER-RUNNING 
MOISTURE. HAVE PUSHED PRECIPITATION POTENTIAL UPWARDS FOR SUNDAY AND 
SUNDAY NIGHT AND THEN HAVE GENERALLY TRENDED GRADUALLY DRIER MONDAY 
THROUGH THURSDAY WHILE MAINTAINING SOME MENTION OF PRECIPITATION 
ACROSS THE FORECAST AREA GIVING AT LEAST A NOD TO THE ECMWF 
SOLUTION. THE TEMPERATURE FORECAST IS A TOUGH NUT TO CRACK WITH SOME 
WILD FLUCTUATIONS SHOWING UP LATE IN THE PERIOD ON THE STATISTICAL 
GUIDANCE. WE WILL ERR TOWARD COOLER FOR NOW. HUSTON

&&

.AVIATION...CLEAR SKIES WERE NOTED ON SATELLITE IMAGERY ACROSS THE 
REGION THIS MORNING WITH THE EXCEPTION OF STRATUS (MVFR TO IFR CIGS) 
LINGERING FROM MONIDA PASS EAST TO THE WYOMING BORDER AND THEN SOUTH 
THROUGH DRIGGS. HIGHER RESOLUTION MODELS SHOW STRATUS ERODING 
THROUGH THE DAY AND THEN MAKING A RETURN IN THE UPPER VALLEY (KIDA) 
AFTER 03Z TONIGHT. HUSTON

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$