000
FXUS65 KPIH 201041
AFDPIH
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
341 AM MST THU NOV 20 2008
.SHORT TERM...TODAY THROUGH SUNDAY. CURRENT IR SATELLITE SHOWING
HIGH CLOUDS RIDING UP WESTERN PERIPHERY OF RIDGE AS BACK DOOR FRONT
SLIDES SOUTHWARD OVER WESTERN MT. THIS TREND WILL CONTINUE FOR
REMAINDER OF DAY WITH TIMES OF HIGH CLOUDS GIVING WAY TO MORE
SUNNY SKIES AND BACK AGAIN. COLD FRONT HAS COME ASHORE ALONG OR/WA
COAST AND WILL REACH ID LATER THIS EVENING. MODELS STILL IN FAIRLY
GOOD AGREEMENT THOUGH NAM12 HAS PULLED BACK ON PRECIP AMOUNTS AND
KEPT PRECIP FURTHER N AND E THAN PREVIOUS RUNS. NEVERTHELESS...RAIN
AND SNOW SHOWERS WILL FALL ACROSS CENTRAL MTNS BY LATE EVENING AND
SHIFT TO ERN HIGHLANDS AFTER MIDNIGHT. SNOWFALL ACCUMULATION WILL
BE RELEGATED TO ELEVATIONS OVER 7000FT WITH AN INCH OR TWO
POSSIBLE OVER SAWTOOTHS AND ONLY AN INCH...MAYBE...OVER ERN
HIGHLANDS. NOT MUCH IN STORE ACROSS SNAKE RIVER PLAIN ASIDE FROM
CLOUDS AND SPOTTY SHOWERS. CHANGED GRIDS TO REFLECT LOWER POPS
AND QPF ACROSS SRN HIGHLANDS WHILE MAKING SMALL TWEAKS TO NRN AND
ERN AREAS. AS SYSTEM MOVES THROUGH CAN EXPECT SOME GUSTY WINDS
AROUND 20 TO 30 MPH THAT WILL QUICKLY SUBSIDE BY LATE FRIDAY
MORNING.
COLD FRONT WILL HAVE MOVED WELL TO OUR EAST BY FRIDAY NIGHT AS
VERY WEAK RIDGING SETS UP OVER ID RESULTING IN A FAIRLY
NICE...SEASONAL DAY ON SATURDAY. NEXT FRONT WILL DROP DOWN FROM
CANADA SAT EVENING BUT FROM RUN TO RUN...MODELS HAVE CONTINUALLY
WASHED OUT FRONT AND REDUCED QPF AMOUNTS TO PRACTICALLY NIL AS JET
SUPPORT WEAKENS CONSIDERABLY. HAVE INCLUDED CHC SNOWSHOWERS OVER
CENTRAL MTNS AS WIND FLOW MIGHT CREATE ENOUGH LIFT FOR SOME PRECIP
THOUGH EXTREMELY LIGHT. BY SUN MORNING ANOTHER LARGE AREA OF HIGH
PRESSURE SETS UP TO OUR WEST BRINGING TRANQUIL WEATHER. RENWICK
&&
.LONG TERM...SUNDAY NIGHT THROUGH WEDNESDAY NIGHT. MODELS AGREE ON
HIGH PRESSURE RIDGE OVER SOUTHEAST IDAHO MONDAY...THEN TROUBLE
STARTS. THE GFS WAVE FIVE CHART INDICATES SPLITTING FLOW PATTERN
DEVELOPING IN THE EASTERN PACIFIC BEGINNING AS EARLY AS SUNDAY
AFTERNOON AND THAT LEADS TO STRONG UNCERTAINTY FOR NEXT WEEK. THE
GFS AND ECMWF BOTH SUPPORT DEVELOPMENT OF A CLOSED LOW OFF THE
CALIFORNIA COAST. TIMING OF THIS SOUTHERN BRANCH FEATURE AND THE
NORTHERN BRANCH TROUGH MOVING INTO BRITISH COLUMBIA ARE QUITE
DIFFERENT IN THE MODELS. ECMWF DOES NOT BRING PRECIPITATION INTO
IDAHO UNTIL THURSDAY. THE GFS IS NOW DEVELOPING A CLOSED LOW IN THE
NORTHERN BRANCH OF FLOW RIGHT OVER THE IDAHO PANHANDLE BY
WEDNESDAY MORNING. CURRENT FORECAST CONTINUES TO STAY WITH THE
ECMWF WHICH OFFERS THE BEST OVERALL CONTINUITY. MOST ENERGY IN THE
ECMWF IS IN THE SOUTHERN BRANCH WITH MULTIPLE LOW PRESSURE CENTERS
MOVING INTO CALIFORNIA. WEDNESDAY AND THURSDAY ARE STILL A BROAD
BRUSH AS DETAILS ARE IMPOSSIBLE TO NAIL DONE AT THIS TIME. RS
&&
.AVIATION...SURFACE COLD FRONT EXPECTED TO CROSS SOUTHEAST IDAHO 03Z
TO 06Z THIS EVENING. BREEZY WEST WINDS 15 TO 25 MPH DEVELOP IN THE
SNAKE RIVER VALLEY THIS EVENING AND DIMINISH BY 18Z FRIDAY.
SCATTERED TO NUMEROUS SHOWERS DEVELOP POST FRONTAL TONIGHT IN THE
MOUNTAINS WITH MORE ISOLATED SHOWERS IN THE VALLEYS THROUGH 18Z
FRIDAY AS WELL. MVFR CEILINGS WITH SHOWERS EXPECTED OVER
MOUNTAINS...BUT REMAIN ISOLATED IN THE LOWER VALLEYS. RS
&&
.PIH WATCHES/WARNINGS/ADVISORIES...
NONE.
&&
$$
