Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 231723
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1023 AM MST TUE DEC 23 2014

.SYNOPSIS...HIGH PRESSURE WILL BUILD OVER THE AREA TODAY. THE
HIGH SHIFTS EAST WEDNESDAY AHEAD OF A COLD WINTER STORM FOR
CHRISTMAS DAY AND FRIDAY.


&&

.DISCUSSION...HIGH PRESSURE CONTINUES TO BUILD OVER THE FORECAST
AREA THIS MORNING...RESULTING IN A DRY AND STABLE AIRMASS. THE
AIRMASS WARMS A BIT TODAY BUT DUE TO POOR MIXING LITTLE OF THIS
WILL BE REALIZED IN VALLEY LOCATIONS. STILL...MAXES ARE PROGGED TO
RUN CLOSE TO SEASONAL NORMS. GOOD N/NE PRESSURE GRADIENT STILL
EXISTS OVER SOUTHERN UTAH...PRODUCING SOME ENHANCED WINDS IN
WASHINGTON COUNTY CANYONS. HOWEVER...HAVE CANCELLED THE WIND
ADVISORY AS THE GUSTS HAVE CONSISTENTLY STAYED BELOW CRITERIA AND
WILL CONTINUE TO WEAKEN THROUGH THE EARLY AFTERNOON.

THE RIDGE CONTINUES TO BUILD THROUGH EARLY TOMORROW...ALLOWING FOR
CONTINUED WARMING. BY WEDNESDAY AFTERNOON THE AXIS SHIFTS EAST OF
THE AREA...AND INCREASINGLY SOUTHWESTERLY FLOW AHEAD OF THE
APPROACHING STORM SYSTEM WILL ALLOW FOR IMPROVED MIXING. 700 MB
TEMPS SHOULD RISE INTO THE -2C TO 0C RANGE...THOUGH THIS WILL NOT
BE FULLY REALIZED IN VALLEY LOCATIONS. STILL...MAXES SHOULD RUN
AROUND 10F ABOVE CLIMO...QUITE MILD FOR THIS TIME OF YEAR.

GUIDANCE CONTINUES TO INDICATE A SIGNIFICANT WINTER STORM FOR
CHRISTMAS DAY...CONTINUING INTO BOXING DAY. STORM SYSTEM AND
ASSOCIATED FRONT INITIALLY NOSE INTO NORTHWEST UTAH AROUND
MIDNIGHT THURSDAY...THEN BLAST A FRONT WEST TO EAST THROUGH MUCH
OF THE STATE CHRISTMAS MORNING. 700 MB TEMPS ARE PROGGED TO
QUICKLY DROP TO THE -14C TO -12C RANGE WITH THE FRONT...ALLOWING
SNOW LEVELS TO DROP DOWN TO VALLEY FLOORS. CURRENT THINKING IS
THAT MOST PEOPLE ON THE WESTERN HALF OF THE STATE WILL WAKE UP TO
SNOW ON THURSDAY...AND THIS WILL CAUSE SIGNIFICANT TRAVEL
DIFFICULTIES FOR CHRISTMAS DAY.

SNOW WILL CONTINUE BEHIND THE FRONT THURSDAY WITH A GOOD DEAL OF
COLD POOL INSTABILITY. SYSTEM THEN APPEARS TO SPLIT OVER THE
AREA...WITH THE MAIN WESTERN END OF THE SYSTEM LINGERING THROUGH
FRIDAY...KEEPING PRECIP GOING AT LEAST OVER THE HIGHER TERRAIN.
HIGH PRESSURE IS PROGGED TO MOVE IN FOR SATURDAY...BUT ANOTHER
LARGE PACIFIC NORTHWEST SYSTEM IS EXPECTED TO MOVE THROUGH EARLY
NEXT WEEK.

UPDATED THE FORECAST EARLIER TO REMOVE WIND ADVISORY WORDING. NO
ADDITIONAL UPDATES PLANNED THIS MORNING.

&&

.AVIATION...CALM WINDS SHOULD BECOME PREDOMINANTLY NORTH TO
NORTHWEST BY 18Z...REMAINING LIGHT THROUGHOUT THE DAY. WINDS ARE
EXPECTED SWITCH TO SOUTHEAST AROUND 03Z AS PER NORM.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH FRIDAY
     MORNING FOR UTZ001>010-014>016-517-518.

WY...WINTER STORM WATCH FROM LATE WEDNESDAY NIGHT THROUGH FRIDAY
     MORNING FOR WYZ021.

&&

$$

PUBLIC...TRAPHAGAN
AVIATION...VERZELLA

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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