Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 281725
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1025 AM MST SUN DEC 28 2014

.SYNOPSIS...A COLD STORM SYSTEM WILL SETTLE INTO THE AREA THROUGH
EARLY MONDAY. A SECOND STORM SYSTEM WILL IMPACT MAINLY THE
SOUTHERN HALF OF THE UTAH MIDWEEK.

&&

.DISCUSSION...THE LEADING SHORT WAVE OF THE DEVELOPING BROAD TROF
OVER THE PACNW AND NRN ROCKIES IS SLIDING EAST INTO WRN WY THIS
MORNING PUSHING A COLD FRONT INTO NRN UT.

PRECIP ALONG AND AHEAD OF THIS FRONT HAS BEEN SPOTTY SO FAR AND
EXPECTED AMOUNTS IN THE WARM ADVECTION PRE FRONTAL ENVIRONMENT
HAVE NOT MATERIALIZED ACROSS THE FAR NRN CWA. SO WILL LOWER SNOW
TOTALS SOMEWHAT FOR THESE ZONES IN THE WINTER STORM STATEMENT
UPDATE.

PRECIP SHOULD STILL TEND TO FILL IN ALONG THE FRONT AS THE DAY
PROGRESSES AND IT SLIDES SWD THRU THE CENTRAL WASATCH FRONT AND
WILL LEAVE ALL EXISTING HEADLINES IN PLACE FOR NOW. SNOW COULD
FOCUS LATER TONIGHT ALONG THE FRONTAL BOUNDARY SOUTH OF PROVO
CONTINUING INTO MON. ALSO...LATEST GUIDANCE DEVELOPS A SMALL
CLOSED LOW AT 700 MB OVER NRN UT LATE TONIGHT INTO MON AND THIS
ENHANCES THE PRECIP ACROSS THE CENTRAL AND NORTHERN WASATCH FRONT
AGAIN MON MORNING WITH ADDITIONAL ACCUMULATION POSSIBLE. SO THERE
IS STILL PLENTY OF OPPORTUNITY FOR SNOW TO CAUSE TRAVEL IMPACTS.

THE ARCTIC AIRMASS THAT IS CURRENTLY SPILLING SWWD INTO THE
DEVELOPING BROAD UPPER TROF CROSSES WY DURING THE DAY MON AND
STARTS TO SPILL INTO NRN UT BY LATE IN THE DAY. THIS TIGHTENS THE
SURFACE PRESSURE AND THERMAL GRADIENT AND THIS PLUS EASTERLY FLOW
ALOFT SHOULD GENERATE STRONG GUSTY CANYON WINDS ALONG THE WASATCH
FRONT. IT STILL APPEARS THIS WILL BE AT LEAST A HIGH END ADVISORY
OR LOW END WARNING EVENT AND WILL BE CONSIDERING A WIND HIGHLIGHT
WITH THE AFTN UPDATE.

OTHERWISE...NO SHORT TERM UPDATES PLANNED AT THIS TIME.

&&

.AVIATION...AT THE SLC TERMINAL...VFR CONDITIONS WITH CIGS AT OR
BELOW 6000 FT AGL ARE EXPECTED TO DETERIORATE INTO THE IFR RANGE
BEGINNING AROUND 20Z...AND PERSISTING THROUGH 23Z OR SO WITHIN
PERIODS OF LIGHT TO MODERATE SNOW. THERE IS A 30 PERCENT CHANCE
THESE CONDITIONS DEVELOP AS EARLY AS 19Z...AND LAST AS LONG AS 02Z.
COLD SURFACES WILL ALLOW SNOW TO ACCUMULATE ON UNTREATED
SURFACES...WITH 1 TO 2 INCHES OF SNOW EXPECTED THROUGH MONDAY.
SOUTHEAST WINDS ARE EXPECTED TO SWITCH TO THE NORTHWEST AROUND 20Z
WITH THE ONSET OF THIS SNOWFALL.

OVERNIGHT THERE IS A 40 PERCENT CHANCE OF IFR TO LIFR CONDITIONS
WITHIN HEAVY SNOW BANDS DURING THE 08-15Z TIMEFRAME MONDAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 4 PM MST MONDAY FOR UTZ003-004-010.

     WINTER STORM WARNING UNTIL 4 PM MST MONDAY FOR UTZ001-002-
     006>009.

WY...WINTER WEATHER ADVISORY UNTIL 10 PM MST MONDAY FOR WYZ021.

&&

$$

WILENSKY/SEAMAN

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)


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