Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 222256
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
356 PM MST MON DEC 22 2014

.SYNOPSIS...A VERY MOIST AND STRONG NORTHWEST FLOW WILL DRY OUT
TONIGHT. HIGH PRESSURE WILL BUILD OVER THE FORECAST AREA FOR
TUESDAY AND WEDNESDAY. ANOTHER STORM SYSTEM WILL IMPACT THE AREA
ON CHRISTMAS DAY.


&&

.SHORT TERM (THROUGH 00Z SATURDAY)...MOIST AND UNSTABLE NORTHWEST
FLOW STILL OVER THE FORECAST AREA THIS AFTERNOON...BUT THE BACK
END OF THE SYSTEM IS IN THE PROCESS OF MOVING EASTWARD OUT OF THE
AREA AND THE ASSOCIATED COLD FRONT IS OVER SOUTHERN UTAH AT THIS
TIME. PRECIPITATION IS DECREASING IN COVERAGE AT THIS TIME AND IS
PRIMARILY CONFINED TO THE HIGHER TERRAIN. REMAINING PRECIP WILL
DIMINISH EARLY THIS EVENING.

STILL SEEING SOME GUSTY WINDS WITH A GOOD NORTHWESTERLY PRESSURE
GRADIENT AND A STRONG JET OVER THE AREA. STRONGEST GUSTS ARE
CURRENTLY OVER NORTHWEST UTAH AND CASTLE COUNTRY...WHERE WIND
ADVISORIES REMAIN IN EFFECT. PRESSURE GRADIENT WILL RELAX THIS
EVENING AS THE MAIN STORM SYSTEM EXITS THE AREA.

HIGH PRESSURE WILL BUILD BACK OVER THE AREA TONIGHT THROUGH
WEDNESDAY MORNING...RESULTING IN DRIER AND MORE STABLE CONDITIONS.
THE STABLE AIRMASS WILL LIMIT VALLEY WARMING TOMORROW...BUT AS THE
MAIN AXIS SHIFTS EAST WEDNESDAY INCREASING SOUTHWEST FLOW WILL
ALLOW FOR BETTER MIXING.

GLOBAL MODELS ARE CONVERGING ON A SOLUTION THAT BRINGS THE
POTENTIAL FOR SIGNIFICANT SNOW TO NORTHERN AND CENTRAL UTAH ON
CHRISTMAS DAY. 12Z GUIDANCE IS A BIT FASTER WITH THE SYSTEM THAN
PREVIOUS RUNS...WITH PRECIP STARTING LATE WEDNESDAY/EARLY THURSDAY
WITH THE ASSOCIATED STRONG COLD FRONT MOVING THROUGH MUCH OF THE
STATE THURSDAY MORNING. 700 MB TEMPS AS COLD AS -14C WOULD EASILY
DROP SNOW LEVELS TO VALLEY FLOORS WITH THE PASSAGE OF THE
BOUNDARY. BEST PRECIP LOOKS TO CONTINUE INTO THURSDAY
AFTERNOON...WITH SHOWERS LINGERING OVER THE HIGHER TERRAIN THROUGH
FRIDAY WITH A TRAILING WAVE STICKING AROUND.

&&

.LONG TERM (AFTER 00Z SATURDAY)...VERY BRIEF RIDGING ENSUES
FOLLOWING THE EXIT OF THE CHRISTMAS TROUGH BY FRIDAY EVENING. THE
ACTION REVAMPS AS A TROUGH DIVES INTO THE PACIFIC NW AND PITCHES ITS
FIRST SHORTWAVE TOWARD THE NORTHERN BORDER ON SATURDAY. THIS
INJECTION OF 700 MB WARM AIR AND MOISTURE ADVECTION OFFER UP AN
INITIAL SHOT OF PRECIPITATION TO THE NORTHERN MOUNTAINS BY SATURDAY
EVENING.

MODELS IN GOOD AGREEMENT ABOUT BRINGING THE TROUGH AND ITS
ACCOMPANYING 50OMB COLD CORE INTO THE HEART OF THE STATE ON SUNDAY.
AMOUNTS AT PRESENT LOOK MODERATE...WITH COVERAGE POSSIBLE STATEWIDE
AND LIKELY AS SNOW TO VALLEY FLOORS SUNDAY INTO MONDAY.

&&

.AVIATION...PERIODIC SHOWERS MAY PLAGUE THE VICINITY THROUGH EARLY
EVENING...KEEPING CEILINGS AT THE SLC TERMINAL FLIRTING WITH THE 6K
AGL MARK THROUGH ABOUT 01Z. THERE IS A 20 PERCENT CHANCE OF MVFR
CIGS DURING THIS TIME. NORTHWEST WINDS SHOULD PERSIST INTO THE EARLY
MORNING HOURS...WITH GUSTS DIMINISHING AFTER 00Z...NUDGING TO
SOUTHEAST AROUND 12Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST THIS EVENING FOR UTZ007>010-
     517.

     WIND ADVISORY UNTIL 10 PM MST THIS EVENING FOR UTZ012.

     WIND ADVISORY UNTIL 8 PM MST THIS EVENING FOR UTZ005.

WY...NONE.
&&

$$

SHORT TERM...TRAPHAGAN
LONG TERM/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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