Area Forecast Discussion
Issued by NWS Pocatello, ID

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000
FXUS65 KPIH 041918
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
118 PM MDT WED MAY 4 2016

.SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT. AMPLIFIED UPPER RIDGE
OVER THE ROCKIES WILL GRADUALLY SHIFT EAST AS A DEEP UPPER LEVEL TROUGH
MOVES INTO THE WEST COAST TONIGHT. THIS UPPER TROUGH CONTINUES TO
DEEPEN AND DEVELOPS AN ANCHORING CUTOFF LOW ALONG THE SOUTHERN
CALIF COAST THROUGH FRIDAY MORNING. THE RESULT IS A TRANSITION TO
SOUTHERLY FLOW OVER EAST ID WHICH IS INITIALLY DRY AND BEGINS TO
ENTRAIN MORE MOISTURE ON THURSDAY AFTERNOON. THUS EXPECT
DEVELOPMENT OF AFTERNOON CONVECTIVE SHOWERS LATE THURSDAY
AFTERNOON....MAINLY OVER ELEVATED TERRAIN. UPPER LEVEL LOW BEGINS
TO MOVE INTO THE SOUTHERN GREAT BASIN AND SOUTHWEST ON FRIDAY.
THIS WILL BRING INCREASING COVERAGE AND INTENSITY OF CONVECTIVE
SHOWERS FOR FRIDAY AND FRIDAY NIGHT AS THE NORTHERN EDGE OF THIS
LOW CREATES ENHANCED INSTABILITY AND MOISTURE. TEMPS COOL SOME
FRIDAY GIVEN THE INCREASED CLOUD COVER AND PRECIPITATION. DSH

.LONG TERM...SAT THROUGH NEXT WED NIGHT. A CLOSED LOW IN THE
SOUTHERN GREAT BASIN WILL BRING MODERATE TO HEAVY PRECIPITATION TO
THE FORECAST AREA FOR SAT/SAT NIGHT/SUN. THE VARIOUS GUIDANCE SUITES
PLACE THE HEAVIEST PRECIPITATION IN DIFFERENT AREAS...AND SO IT
MIGHT MAKE BETTER SENSE TO PAINT WITH A VERY BROAD BRUSH. MAINLY
FOLLOWED THE PATTERN OF THE GFS WITH MODIFICATION TOWARDS THE
ECMWF. THE CLOSED LOW MOVES OUT SUN OR SUN NIGHT...BUT THIS ONLY
ALLOWS A TROUGH TO DIG SOUTHWARD OUT OF CANADA AND PUT SOME LIGHT
PRECIPITATION ALONG THE ID-MT BORDER REGION. PRECIPITATION TAILS
OFF SUDDENLY WED...WITH A STRONG POTENTIAL FOR NO PRECIPITATION IF
THE ECMWF SOLUTION WINDS UP BETTER. HIGH TEMPERATURES FOR THE
WEEKEND WILL BE DOWN 10 DEG F FROM THE PREVIOUS FRI...AND ONLY
WARM SLIGHTLY WITH ALL THE CLOUD COVER AND PRECIPITATION
CONTINUING. SNOW LEVEL WILL STAY HIGH IN THE WARM AIR MASS...WITH
LOWEST SNOW LEVEL EXPECTED TO LOWER ONLY TO AROUND 8000 FEET IN
THE ID-UT BORDER REGION...WHEN THE COLD CORE LOW IS APPROACHING
FROM THE SOUTH. MONDAY HAS THE BEST POTENTIALLY WINDY DAY AND
EVENING AS THE LOW FROM THE NORTH BEARS DOWN ON SOUTHERN IDAHO.
MESSICK

&&

.AVIATION...WIDESPREAD VFR CONDITIONS AND MODERATE WINDS EXPECTED
THROUGH THE PERIOD. SLIGHT CHANCE OF SHOWERS OVER THE WEST CENTRAL
MOUNTAINS TONIGHT THAT WILL NOT IMPACT ANY TAF SITES.  DSH

&&

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

$$



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