Area Forecast Discussion
Issued by NWS Pocatello, ID

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FXUS65 KPIH 192007
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
107 PM MST WED NOV 19 2014

.SHORT TERM...TONIGHT THROUGH SATURDAY.
INVERSIONS HAVE BEEN BREAKING WITH TEMPERATURES ABOVE FREEZING
THIS AFTERNOON ACROSS THE SNAKE RIVER PLAIN. EXPECT MAINLY BENIGN
WEATHER TO CONTINUE THROUGH FRIDAY AFTERNOON. HAVE SOME VERY WEAK
PACIFIC SYSTEMS BREAKING DOWN THE UPPER LEVEL RIDGE AND COULD SEE
SOME LIGHT SNOW MAINLY IN THE MOUNTAINS. THROUGH FRIDAY AFTERNOON
EXPECTING NOTHING MORE THAN AN INCH OR SO IN THE CENTRAL MOUNTAINS
AND UPPER SNAKE RIVER HIGHLANDS. TEMPERATURES THROUGH FRIDAY
SHOULD BE NEAR OR SLIGHTLY BELOW SEASONAL NORMALS.

MAIN FOCUS CONTINUES TO BE ON A MUCH STRONGER SYSTEM TO AFFECT
THE ENTIRE REGION FRIDAY NIGHT THROUGH SATURDAY EVENING. IT IS A
QUICK MOVING SYSTEM WITH EXTENSIVE PACIFIC MOISTURE ENTRAINED IN
THE WESTERLY FLOW ALOFT. HAVE ISSUED A WINTER STORM WATCH FOR ALL
OF THE MOUNTAINS IN SOUTH CENTRAL AND SOUTHEAST IDAHO BEGINNING
FRIDAY NIGHT OR SATURDAY MORNING. DO EXPECT SNOW LEVELS TO RISE TO
ABOUT 5500 FEET EARLY ON SATURDAY. THERE WILL BE A THREAT FOR A
PERIOD OF FREEZING RAIN EARLY SATURDAY MORNING IN THE SNAKE RIVER
PLAIN BEFORE TEMPERATURES RISE ABOVE FREEZING BUT WITH THIS SYSTEM
STILL A COUPLE DAYS OUT...TEMPERATURE FORECASTS COULD BE SUBJECT
TO CHANGE. THINK IT IS POSSIBLE FOR SNOW AMOUNTS OF 8 TO 14 INCHES
AT ELEVATIONS ABOVE 5500 FEET ESPECIALLY OVER MOUNTAIN PASSES WITH
THE POTENTIAL FOR HAZARDOUS TRAVEL LATE FRIDAY NIGHT THROUGH
SATURDAY. EXPECT A COLD FRONTAL PASSAGE SATURDAY WITH THIS SYSTEM
AND WINDS ARE EXPECTED TO INCREASE AND BLOWING AND DRIFTING SNOW
WILL ALSO BE A THREAT DURING THE DAY ON SATURDAY WITH BREEZY TO
WINDY CONDITIONS EXPECTED.
GK

.LONG TERM...SATURDAY NIGHT THROUGH WEDNESDAY. AN ACTIVE PATTERN
WILL CONTINUE INTO NEXT WEEK...PRE-THANKSGIVING. MOISTURE WILL KEEP
SNOW GOING IN THE MOUNTAINS...WITH THE VALLEY SEEING AN OCCASIONAL
CHANCE FOR RAIN AND SNOW AS WAVES CROSS OVER EASTERN IDAHO. RIGHT
NOW...IT LOOKS LIKE THE NEXT BEST CHANCE OF PRECIPITATION AREA WIDE
WOULD SUNDAY NIGHT INTO MONDAY ALTHOUGH THE MODELS ARE OFF A BIT ON
TIMING. AS WE REACH MIDWEEK...THE MODELS HAVE VARIED WIDELY. THE GFS
KEEPS THE RIDGE WITH MOISTURE FALLING OVER THE CENTRAL AND EASTERN
MOUNTAINS FOR THE MOST. THE ECMWF DROPS A VERY STRONG STORM INTO OUR
AREA FROM THE NORTH AND WEST. BASED ON EARLIER ENSEMBLES...THERE
SEEMS TO BE AGREEMENT ON SOMETHING WITH NORTHWESTERLY FLOW WHICH
WOULD FAVOR A PATTERN CLOSER TO THE GFS. WE DECIDED TO KEEP THE
FORECAST THE SAME AND SIMILAR TO PREVIOUS DAYS...FAVORING HIGHER
CHANCES ACROSS THE CENTRAL AND EASTERN MOUNTAINS. IT WILL BE BREEZY
AT TIMES...SO BLOWING SNOW COULD REMAIN A PERSISTENT ISSUE IN THE
MOUNTAINS. IN THE VALLEYS...IMPACTS WILL BE DEPENDENT ON TIMING OF
RAIN/SNOW IN THOSE AREAS. BOTTOM LINE...IF YOU HAVE TRAVEL PLANS FOR
THANKSGIVING YOU WILL NEED TO KEEP A CLOSE ON THE SITUATION DAILY TO
SEE IF YOUR TRAVEL DAY IS GREATLY IMPACTED OR NOT.  KEYES
&&

.AVIATION...HIGHER CLOUDS CONTINUE TO MOVE ACROSS THE AREA TODAY
WITH NO RESIDUAL STRATUS OR FOG. WE WILL SEE A WEAK SYSTEM MOVING
INTO THE REGION TONIGHT AND THURSDAY. CEILINGS WILL GRADUALLY LOWER
LATE THIS EVENING INTO THE MORNING HOURS. WE SHOULD SEE LIGHT SNOW
SPREAD ACROSS THE AREA AS WELL. FOR NOW WE ARE GOING WITH VCSH AND
VFR AT ALL SITES THROUGH MID MORNING. THE CROSS SECTIONS DROP
CONDITIONS TO MVFR/IFR TOMORROW AS THE SYSTEM IS OVERHEAD. WE AREN`T
TOO CONFIDENT IN THAT HAPPENING ESPECIALLY FOR THE VALLEY SITES
WHERE RAIN WOULD FALL AS TEMPERATURES WARM UP. LATER SHIFTS WILL
NEED TO DETERMINE IF INDEED THOSE CONDITIONS WILL DEVELOP. KEYES

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY
EVENING IDZ019-022-023-025-032.

WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SATURDAY
AFTERNOON IDZ018-031.

&&

$$






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