Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 232054
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
154 PM MST SUN NOV 23 2014

.SHORT TERM...TONIGHT THROUGH WEDNESDAY. A MINOR UPPER WAVE WILL
MOVE SE THRU ID TONIGHT SPREADING LIGHT SNOW TO MAINLY THE MTNS.
EXPECTING 1 TO 3 INCHES IN THE CENTRAL MTNS AND EASTERN HIGHLANDS.
ONLY EXPECT ISOLD SNOW/RAIN SHOWERS WITH MINIMAL ACCUMULATIONS
ELSEWHERE. UPPER RIDGING BUILDS UP OVER THE W COAST ON MON...
BRINGING AN END TO MOST OF THE PRECIP. SNOW SHOWERS WILL LINGER
OVER THE EASTERN HIGHLANDS MON MORN...DIMINISHING DURING THE AFTN.
THE BREAK DOES NOT LAST LONG AS ANOTHER MINOR WAVE MOVES DOWN THE
NW FLOW INTO ID BY TUE MORN. THIS SYSTEM...LIKE THE PREVIOUS
ONE...IS EXPECTED TO RESULT IN MOST OF THE PRECIP IN THE MTNS DUE
TO UPSLOPE ENHANCEMENT. ACCUMULATIONS OF 3 TO 6 INCHES IN THE
CENTRAL MTNS AND EASTERN HIGHLANDS...AND LESS THAN AN INCH IN THE
SNAKE RIVER PLAIN. PRECIP TAPERS OFF BY WED MORN AS UPPER RIDGE
BUILDING PUSHES THE SYSTEM OFF TO THE EAST . HEDGES

.LONG TERM...WED NIGHT THROUGH NEXT SUN NIGHT. 500MB 5-WAVE PROG HAS
BEEN SOMEWHAT UNSTABLE...NEVER MIND FACTORING IN SHORTWAVES...THUS
FORECAST DURING THIS TIME HAS LOW CONFIDENCE...ESPECIALLY AFTER THU
NIGHT. CURRENTLY THE LONGWAVE FORECAST IS A TRANSITION FROM A
LOW-AMPLITUDE RIDGE TO TROUGHING BY THE WEEKEND. THIS IS A STRONG
CHANGE FROM A HIGH AMPLITUDE RIDGE WEAKENING TO FLATTER ZONAL FLOW.
AND AS PREVIOUS SHIFT INDICATED...THERE HAVE BEEN LARGE CHANGES IN
THE GFS SOLUTION V. THE ECMWF. HOWEVER...THE GFS CONTINUES WETTER
WITH THE FEATURES THAT COME IN AFTER THU NIGHT. TEMPERATURES ARE ALL
OVER THE PLACE...AND AT THIS TIME OF YEAR MAKES FOR A VERY UNCERTAIN
SNOWFALL FORECAST...AS TEMPERATURE DIFFERENCES ARE LARGE BY FRI WITH
THE GFS MUCH WARMER AND THE ECMWF COLDER. THE BOTTOM LINE IS DO NOT
BE SURPRISED AS THE FORECAST ENTERS THE SHORT TERM FOR CHANGES.
HOWEVER...SAT AND SUN HAVE A THREAT OF RAIN AND SNOW FOR HOLIDAY
TRAVEL. I DO NOT SEE THE FORECAST BECOMING SUNNY AND DRY...BUT THE
DIFFERENCE IS MORE RAIN VERSUS SNOW...AND POSSIBLY HEAVY SNOW.
MESSICK

&&

.AVIATION...HIGH MOISTURE IN THE BOUNDARY LAYER CONTINUES AN
UNCERTAIN FORECAST FOR CIG AND VSBY. THERE IS A WEAK FEATURE TONIGHT
THAT COULD GENERATE MOUNTAIN SHOWERS NEAR KPIH AND KIDA...BUT ON THE
WHOLE EXPECTING NOTHING BUT MID-LEVEL CIGS EARLY THIS EVENING. BY
THE LATE NIGHT...MARGINAL VFR CIGS ARE POSSIBLE WITH DIURNAL COOLING
AND THE CLEARING OF THE MID-LEVEL CLOUDINESS AT JUST THE RIGHT TIME.
THERE IS A LARGE DISAGREEMENT BETWEEN THE GFS AND NAM...BUT THE NAM
HAS BEEN QUITE WRONG LATELY AND HAVE LESS TRUST IN IT THAN TWO DAYS
AGO. HAVE AVERAGED OUT THE CIG FORECAST BETWEEN THE PRODUCT SUITES.
VSBY SHOULD BE UNRESTRICTED...HELPED BY A STRONGER-THAN-NORMAL WIND
FOR MUCH OF TONIGHT. NO WEATHER IMPACT EXPECTED UNDER THE NORTHWEST
FLOW AT KSUN. MESSICK

&&

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

$$






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