Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 242054
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
155 PM MST TUE FEB 24 2015

.SHORT TERM...TONIGHT THROUGH FRIDAY. EARLY AFTERNOON SATELLITE
IMAGERY WAS SHOWING A MODEST TROUGH SWEEPING SE INTO THE CANADIAN
ROCKIES WHILE ATTENDING MOISTURE SPREAD SOUTH ACROSS WRN MONTANA.
BOTH THE NAM AND GFS WERE SHOWING A LIGHT DUSTING OF SNOW ACROSS THE
ISLAND PARK AREA TONIGHT WITH THIS FIRST PASSING CLIPPER. A COLD
ARCTIC AIRMASS PLUNGES SOUTH ACROSS THE DAKOTAS AND MONTANA BEHIND
THE EXITING WAVE WEDNESDAY RESULTING IN UPSLOPE SNOWFALL ALONG AND
NORTHEAST OF THE CONTINENTAL DIVIDE. WEAK TRAILING ENERGY ALONG THE
DIVIDE WEDNESDAY AFTERNOON MAY BE ENOUGH TO SUPPORT SOME LIGHT
SNOWFALL ACROSS THE NE MOUNTAINS. BY WEDNESDAY NIGHT...A FAIRLY
DECENT DISTURBANCE TOPS THE RIDGE OFF THE PAC COAST AND BEGINS TO
DIG SLOWLY SSE INTO WRN OREGON BY FRIDAY AFTERNOON. THE GFS...ECMWF
AND NAM ARE ALL IN FAIRLY GOOD AGREEMENT TODAY THAT THE ASSOCIATED
WARM-OVERRUNNING PRECIPITATION WILL ADVANCE ACROSS OREGON WEDNESDAY
NIGHT...THEN CLIP THE WRN MOST ZONES THURSDAY/THURSDAY NIGHT AS THE
LOW REACHES THE WASHINGTON COAST. THE BEST CHANCE FOR PRECIPITATION
APPEARS TO BE FRIDAY WHEN THE LOW DIGS INTO WRN OREGON. HAVE
GENERALLY DECREASED THE PRECIPITATION POTENTIAL ACROSS THE AREA
WEDNESDAY NIGHT/THURSDAY MORNING GIVEN THE GOOD MODEL AGREEMENT AND
THEN FAVORED THE WRN MOST ZONES THURSDAY NIGHT/FRIDAY AS THE LOW
MAKES LANDFALL. THE TRACK OF THE LOW WILL MAKE ALL THE DIFFERENCE IN
THE AMOUNT OF SNOWFALL THAT WE MAY ACTUALLY SEE...SO EXPECT SOME
WAFFLING AS THE MODELS LOCK INTO A SOLUTION. STATISTICAL GUIDANCE
GENERALLY RUNNING NEAR CLIMATOLOGICAL NORMS FOR THIS TIME OF YEAR
AND HAVE NO PROBLEM TAGGING ALONG FOR THE RIDE. HUSTON

.LONG TERM...FRIDAY NIGHT THROUGH TUESDAY NIGHT. FAIR AGREEMENT
AMONG MODELS ON EVOLUTION OF SPLIT FLOW PATTERN HEADING INTO THE
WEEKEND. GFS IS TRENDING SLIGHTLY WEAKER WITH THE CLOSED LOW
CIRCULATION AS IT DEVELOPS OFF THE WA/OR COAST. NORTHERN BRANCH OF
SPLIT FLOW REMAINS OVER MT LEAVING A WEAK FLOW OVER SE IDAHO. EXPECT
DISORGANIZED CONVECTIVE ACTIVITY ACROSS THE AREA UNTIL SUNDAY
MORNING AS RIDGING BRIEFLY MOVES OVER US. GFS/ECMWF BRING A SECOND
TROUGH/UPPER LOW OUT OF BC MONDAY WITH THE ECMWF INDICATING A MORE
SOUTHWARD TRAJECTORY ALONG WITH THE GEM...PLACING UPPER LOW ALONG
THE OR COAST TUESDAY AFTERNOON. GFS DRIVES UPPER TROUGH RIGHT OVER
IDAHO BY TUESDAY NIGHT...BUT GFS ENSEMBLE LENDS A GREAT DEAL OF
UNCERTAINTY AS MEAN TROUGH AXIS EXTENDING FROM THE DAKOTAS TO NEW
MEXICO. HINSBERGER
&&

.AVIATION...EXPECTING VFR CONDITIONS TO CONTINUE THROUGH THE PERIOD.
A WEAK UPPER TROUGH WILL PUSH SOUTHEAST THIS AFTERNOON BRINGING MID
AND UPPER LEVEL CEILINGS AND SOME GUSTY SOUTHWEST SURFACE WINDS.
HINSBERGER
&&

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

$$










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