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000
FXUS65 KPIH 080339
AFDPIH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE POCATELLO ID
839 PM MST SAT DEC 7 2013

.UPDATE...WINTER CONTINUES TO MAKE ITS PRESENCE FELT ACROSS
EASTERN IDAHO THIS EVENING. TROUGH AXIS REMAINS OVERHEAD THIS
EVENING. WEAK HINT OF 700MB AXIS SLIDING INTO EASTERN IDAHO PER IR
SAT IMAGERY. HOWEVER...EVEN IF MAIN MOISTURE BATCH SHIFTS EAST PER
COLDEST CLOUD TOPS...SURFACE FLOW FAVORS UPSLOPE PUSHING INTO THE
SOUTHERN AND EASTERN HIGHLANDS IN THE PRESENCE OF CONTINUED LOW
LEVEL MOISTURE. TEMP PROFILES FAVORABLE FOR CONTINUED LIGHT SNOW
WITHIN THE STRATUS LAYER. THERE IS A STRONG POSSIBILITY FOR
EXTENDING THE WINTER WEATHER ADVISORY FOR ADDITIONAL SNOWFALL
THROUGH THE REMAINDER OF THE NIGHT. SURFACE LOW NEAR KDIJ/KJAC
WITH STRONG HIGH OVER MONTANA HAS ALLOWED ARCTIC AIR TO BEGIN TO
SPILL INTO EASTERN IDAHO...AND NORTHERLY GRADIENT KEEPING WINDS
ELEVATED ENOUGH TO PUSH WIND CHILLS AROUND -30 AND BELOW IN
PLACES NEAR THE MONTANA BORDER. THUS HAVE ALREADY ISSUED WIND
CHILL WARNING FOR UPPER SNAKE HIGHLANDS ZONE 19 BELOW 7000 FEET
WITH EXPIRATION IN LINE WITH WIND CHILL WARNING FOR SNAKE PLAIN.
TIMING FOR WIND CHILLS IN SNAKE PLAIN STILL LOOK REASONABLE FOR
06Z AND BEYOND FOR BULK OF THOSE ZONES. WILL HOLD OFF AS LONG AS
POSSIBLE GIVEN SUBTLE SIGNALS ON IR IMAGERY WITH RESPECT TO WINTER
WEATHER ADVISORY BUT WOULD LEAN AT THIS TIME TOWARD EXTENSION OF
AT LEAST SOME OF THE REGION TONIGHT. DMH

.AVIATION...HAVE HAD TO EXTEND THE POOR CIGS AND VSBYS AT KSUN AND
KPIH AS THE UPSLOPE WIND AND AVAILABLE MOISTURE HAS KEPT THE SNOW
GOING...WITH A SECOND SURGE GOING ON RIGHT NOW IN THE KPIH VICINITY.
KSUN THE DELAY IS LONG ENOUGH WHERE CIGS WILL NOT RISE ABOVE FIELD
MINIMUMS UNTIL AFTER CLOSURE. MEANWHILE...SNOW IS ENDING AT KIDA AND
KBYI...THOUGH A LITTLE LATER THAN PREVIOUS THINKING. A BRIEF BREAK
IN THE MORNING IS EXPECTED...THEN DETERIORATING CIGS AND VSBYS WITH
THE NEXT ARCTIC TROUGH AND FRONT THAT COMES DOWN SUN NIGHT. MESSICK

&&

.SHORT TERM...

.LONG TERM...


&&

.PREV DISCUSSION... /ISSUED 128 PM MST SAT DEC 7 2013/

SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT. SATELLITE IMAGERY
SHOWING SHARP UPPER TROUGH MOVING ACROSS SOUTHERN IDAHO. MODELS
CONTINUE TO SHOW HEAVIEST PRECIP OVER SOUTHEASTERN HIGHLANDS THIS
AFTERNOON AS THE SURFACE LOW TRAVELS ACROSS UTAH. ADDITIONAL SNOW
AMOUNTS OF 1 TO 2 INCHES ARE EXPECTED IN THE VALLEYS AND ABOUT 3 TO
5 INCHES IN THE HIGH COUNTRY THIS EVENING. IN THE WAKE OF THE
SURFACE LOW...WINDS WILL REMAIN FAIRLY STRONG IN THE VALLEYS OF THE
CENTRAL MOUNTAINS AND THE SNAKE PLAIN. COMBINED WITH THE BITTERLY
COLD TEMPERATURES...THIS WILL MEAN VERY LOW WIND CHILLS THROUGH THE
NIGHT AND INTO TOMORROW. CURRENT HEADLINES LOOK FAIRLY GOOD...BUT
HAVE ADDED ZONE 21 TO THE WIND CHILL WARNING FOR TONIGHT. ZONE 17
WILL BE BORDERLINE WIND CHILL WARNING.

A STRONG 1042MB HIGH WILL BUILD INTO IDAHO ON MONDAY...INDICATING A
CONTINUATION OF EXTREMELY COLD TEMPERATURES WITH SINGLE DIGIT HIGHS
BOTH SUNDAY AND MONDAY ACROSS MUCH OF THE AREA AND LOWS WELL BELOW
ZERO...ESPECIALLY NOW THAT MUCH OF THE AREA HAS SOME SNOW COVER.
HINSBERGER

LONG TERM...WEDNESDAY THROUGH SATURDAY. THE COLD NORTHERLY FLOW
WILL BE REPLACED BY A BRIEF RIDGE OF HIGH PRESSURE WITH SLIGHT
WARMING THROUGH THE END OF THE WEEK. EMBEDDED PIECES OF STORM
ENERGY WILL START TO PUSHING THROUGH FRIDAY AND SATURDAY. TIMING
HOWEVER IS HIGHLY SUSPECT AT THIS TIME AS THE FORECAST MODELS ARE
HAVING DIFFICULTY IN HANDLING THIS TRANSITION. KEY IS TEMPERATURES
WILL WARM SLIGHT TOWARDS MORE SEASONAL VALUES. IMPACTS AT THIS
POINT INDICATE SNOW SHOWERS MAINLY OVER HIGHER TERRAIN AND ALONG
THE IDAHO MONTANA BORDER REGION. IF PATTERN OPENS UP MORE FROM THE
PACIFIC IN WESTERLY FLOW...COULD EXPECT HIGHER PRECIPITATION
AMOUNTS TO OCCUR THE LATER WE GET INTO NEXT WEEKEND.

PRESTON

AVIATION...A LOW PRESSURE SYSTEM MOVING THROUGH REGION THIS
AFTERNOON WILL SLOWLY EXIT OVERNIGHT.  WIDESPREAD SNOW WILL CONTINUE
THROUGH EARLY THIS EVENING WITH MVFR TO IFR CONDITIONS.  OVERNIGHT
WINDS WILL INCREASE AND MAY CAUSE BLOWING DRIFTING SNOW AS WELL AS
TURBULENCE.  ON TUESDAY CONDITIONS WILL IMPROVE TO VFR BY 18Z.

PRESTON

&&

.PIH WATCHES/WARNINGS/ADVISORIES...
WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING IDZ017-021.

WIND CHILL WARNING UNTIL 11 AM MST SUNDAY IDZ020-021.

WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING IDZ022>025.

WIND CHILL WARNING UNTIL 11 AM MST SUNDAY BELOW 7000 FEET FOR
THE IDZ019.

&&

$$