Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 262052
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
152 PM MST WED NOV 26 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY. UPPER RIDGING OVER THE
WESTERN US TODAY WILL FLATTEN TO ZONAL FLOW BY THU NIGHT. THIS
WILL ALLOW SOME PAC MOISTURE TO STREAM INTO ID...SETTING OFF A FEW
SHOW SHOWERS IN THE CENTRAL MTNS ON THU. A MAJOR UPPER WAVE OVER
BC WILL DROP SOUTHWARD INTO THE PAC NW BY SAT MORN. THIS WILL
ALLOW THE POLAR FRONT TO SLOWWLY SAG SOUTHWARD...FORCING PRECIP TO
BECOME MORE WIDESPREAD FRI THRU SAT. MOST OF THE PRECIP WILL BE IN
THE CENTRAL MTNS AND UPPER SNAKE HIGHLANDS ON FRI...BUT OVER THE
ENTIRE FCST AREA BY SAT. LOOKS LIKE A SUBSTANTIAL FLOW OF PAC
MOISTURE INTO THE REGION. WARM TEMPS WILL KEEP SNOW CONFINED TO
THE MTNS WHERE SIGNIFICANT ACCUMULATIONS ARE EXPECTED IN THE
CENTRAL MTNS/UPPER SNAKE HIGHLANDS FRI AND SAT. THE LOWER
ELEVATIONS... INCLUDING THE SNAKE RIVER PLAIN SHOULD SEE RAIN FRI
NIGHT AND SAT. TEMPS WILL REMAIN MILD THU THRU SAT. HEDGES

.LONG TERM...SAT NIGHT THROUGH NEXT WED NIGHT. WINTER STORM WRAPS UP
DURING THIS TIME. MAJOR CHANGE IS THE NORTHERLY WIND THAT BRINGS IN
POLAR AIR AND MUCH COLDER TEMPERATURES FOR SUN AND SUN NIGHT. BOTH
GFS AND THE ECMWF HAVE THE SAME SCENARIO...WITH THE EXCEPTION THAT
THE ECMWF BRINGS IN MUCH COLDER AIR AND A DRIER SOLUTION FOR THE
PART OF THE FORECAST AFTER SUN NIGHT. THIS IS BECAUSE OF A SPLIT
THAT DEVELOPS IN THE UPPER LEVEL FLOW IN THE EASTERN PACIFIC THAT
MERGES OVER OR NEAR IDAHO. THE GFS KEEPS SOUTHERN IDAHO ON THE WARM
SIDE WITH A CLOSED LOW OFF THE CALIFORNIA COAST PUMPING UP WARM
MOIST AIR FOR MORE PRECIPITATION AND MUCH WARMER TEMPERATURS THAN
SUN. THE ECMWF KEEPS EASTERN IDAHO ON THE COLD SIDE...WHICH HAS LESS
MOISTURE AVAILABLE AND THE COLDER AIR. WHICH SOLUTION IS CORRECT IS
THE MAIN FORECAST PROBLEM FOR THIS PERIOD. LATELY THE GFS HAS BEEN
PERFORMING BETTER...BUT BOTH FRANKLY HAVE BEEN SCORING LOW IN THE
VERIFICATION DEPARTMENT WHEN IT COMES TO TEMPERATURES. HAVE DECIDED
TO LEAVE ALONE AND WAIT FOR SOME SORT OF CONSENSUS TO DEVELOP.
MESSICK

&&

.AVIATION...PRESSURE GRADIENTS OVER EASTERN IDAHO ARE FINALLY
RELAXING A LITTLE BIT AND WINDS SHOULD NOT GUST AS STRONG. DRY AIR
BEHIND LAST NIGHTS FRONT WILL KEEP SKIES CLEAR AND THE ELEVATED WIND
SHOULD PREVENT ANY MORE FOG OR STRATUS. CIG DEVELOPS DURING THU
MORNING...LOWERS THU NIGHT...BUT NO PRECIPITATION EXPECTED UNTIL
LATE FRI NIGHT. MESSICK

&&

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

$$






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