Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 251607
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
907 AM MST THU DEC 25 2014

.UPDATE...CIRCULATION EVIDENT ON RADAR ALONG IDAHO/WYOMING BORDER
THIS MORNING. HEAVY SNOW BAND WORKING SOUTH ALONG I-15 CORRIDOR
WITH SOME ENHANCEMENT IN AREA OF SFC WIND CONVERGENCE NORTH OF
I-86. SNOWFALL RATES APPROX 1 INCH/HOUR PER SOME SPOTTER
OBSERVATIONS DURING HEAVIEST BAND. HAVE UPDATED POP/WX/QPF/SNOW
PER RADAR TRENDS. TWO AREAS OF STRONG WINDS: MAGIC VALLEY AND IN
UPPER SNAKE REGION ESPECIALLY WHERE NORTHWEST FLOW ALIGNED WITH
EXIT REGIONS OF CENTRAL MTN VALLEYS. MODIFIED AREAS OF BLOWING
SNOW IN GRIDS WHERE SUSTAINED WINDS EXPECTED TO REMAIN ABOVE
15KTS. AREA WEB CAMS SHOW ONLY WEAK SNOWFALL IF ANY IN THE
CENTRAL MTNS SO HAVE DROPPED HEADLINES FOR THAT AREA EARLY. WILL
KEEP REMAINDER OF HEADLINES IN PLACE FOR CURRENT SNOW AND/OR
BLOWING SNOW. EXPECT TRAVEL DIFFICULTIES TO CONTINUE MUCH OF THIS
CHRISTMAS DAY. DMH


&&

.PREV DISCUSSION... /ISSUED 248 AM MST THU DEC 25 2014/

SHORT TERM...COLD FRONT IS COMING THROUGH WITH A BIT MORE POWER
THAN EXPECTED...MAINLY IN THE WINDS WITH SOME SPOTTER SNOWFALL
AMOUNTS/SNOTEL REPORTS ALREADY AT THE HIGH END OF THE PREVIOUS
FORECAST. HAVE SLOWED THE DEPARTURE OF THIS LOW AS THE FIRST SIX
HOURS OF THE FORECAST HAS QUITE A BIT OF PRECIPITATION STILL TO
GO. HOWEVER...THE NORTHERLY FLOW DOES TAKE OVER BY AFTERNOON AND
DRIER AND MUCH COLDER AIR PUSHES INTO SOUTHERN IDAHO. ANOTHER
WINTER STORM STARTS BEARING DOWN ON THE REGION ON SAT...WITH NOT
MUCH IN THE WAY OF SOUTHERLY FLOW TO WARM UP TEMPERATURES. THE
CLOUD COVER SAT NIGHT KEEPS OVERNIGHT LOWS FROM CRASHING LIKE THE
PREVIOUS TWO NIGHTS...BUT STILL ONLY WARMING TO SLIGHTLY BELOW
NORMAL. WINDS WILL GET BREEZY TO WINDY WITH THIS STORM AS IT
APPROACHES. IT LOOKS LIKE A STORM THAT WILL GENERATE ADVISORIES AT
LEAST...AND POSSIBLY WARNINGS IN PARTS OF THE FORECAST AREA.
MESSICK

LONG TERM...SUNDAY THROUGH NEXT THURSDAY. THE GFS AND ECMWF
CONTINUE TO SHOW A VIGOROUS LOW PRESSURE TROUGH DIGGING INTO THE
REGION SUNDAY WITH A WEAK CLOSED UPPER CIRCULATION POSSIBLY
DEVELOPING OVER THE NRN GREAT BASIN AS EARLY AS MONDAY MORNING WHICH
WOULD SUGGEST A SLOWER PROGRESSION OF THE TROUGH AS IT GRADUALLY
DRIFTS SOUTH INTO NEVADA/UTAH BY TUESDAY MORNING. THUS HAVE BOOSTED
THE CHANCE FOR PRECIPITATION SUNDAY AND TO A LESSER EXTENT MONDAY
ACCOUNTING FOR THE ANTICIPATED SLOWER PROGRESSION. ADVISORY LEVEL
SNOWFALL IS EXPECTED OUT OF THIS STORM FOR THE SNAKE RIVER VALLEY
WITH NEAR WARNING AMOUNTS ACROSS PORTIONS OF THE ERN AND CNTRL
MOUNTAINS WHICH WILL IMPACT TRAVELERS RETURNING HOME SUNDAY/MONDAY.
FOR MONDAY THROUGH WEDNESDAY...A COLD NNE ARCTIC FLOW WILL
OVERSPREAD SE IDAHO WITH DAYTIME HIGHS GENERALLY RUNNING 15 TO 20
DEGREES BELOW NORMAL. SOME MODERATION IS EXPECTED BY THURSDAY AS THE
FLOW ALOFT TURNS MORE NORTHWESTERLY. HUSTON

AVIATION....A LOW PRESSURE TROUGH AND ACCOMPANYING SNOWFALL WERE
SPREADING THROUGH SE IDAHO THIS MORNING. IFR CIGS/VIS WERE NOTED AT
KPIH AND KIDA EARLY THIS MORNING WITH THE UPPER TROUGH AXIS STILL
LOCATED TO OUR WEST. THE LOW IS EXPECTED TO SHIFT SE OF THE AREA
AFTER 18Z WITH GRADUALLY IMPROVING CONDITIONS THROUGH 09Z AS A DRIER
NORTH FLOW ALOFT WORKS INTO THE REGION. NW DOWNSLOPE WINDS HAVE
ALREADY SPREAD INTO KSUN WITH VFR CIGS EXPECTED TO CONTINUE THROUGH
MID-MORNING WITH VCSH. HUSTON

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 5 PM MST THIS AFTERNOON
IDZ017-019>024.

WINTER STORM WARNING UNTIL 5 PM MST THIS AFTERNOON IDZ025.

&&

$$






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