Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 212329
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
429 PM MST FRI NOV 21 2014

.SYNOPSIS...A MILD WESTERLY FLOW WILL BE OVER THE AREA TONIGHT. A
COLD FRONT WILL MOVE INTO NORTHERN UTAH SATURDAY AFTERNOON THEN
PUSH THROUGH THE REST OF THE AREA SATURDAY NIGHT. A COLD MOIST
NORTHWEST FLOW WILL CONTINUE OVER THE AREA THROUGH MONDAY.

&&

.SHORT TERM (THRU 00Z TUE)...A FEW SHALLOW CONVECTIVE CLOUDS
DEVELOPED OVER THE SRN MTNS THIS AFTERNOON WITH JUST HIGH THIN
CLOUDS ACROSS THE NORTH. TEMPS REACHED MILD LEVELS WITH READINGS
SEVERAL DEGREES ABOVE NORMAL IN MOST AREAS.

EXPECT INCREASING HIGH CLOUDS TONIGHT AS THE CLOUD SHIELD AHEAD
OF THE THE VIGOROUS BUT LOW AMPLITUDE SHORT WAVE TROF SPREADS
ACROSS THE GREAT BASIN. LATEST GUIDANCE CONTINUES TO BRING THIS
WAVE INTO THE PACNW TONIGHT AND ADVANCE IT RAPIDLY EWD DURING THE
DAY SAT. A WELL DEFINED WARM FRONT CROSSES NRN UT SAT MORNING AND
THE ASSOCIATED COLD FRONT PUSHES THROUGH DURING THE AFTN PASSING
SLC AROUND 4PM LOCAL TIME.

THE PRECIP THREAT WITH THE WARM FRONT SHOULD BE CONFINED TO THE
NRN MTNS AND WASATCH FRONT VALLEYS FAVORED BY SOUTH FLOW. THE COLD
FRONT LOOKS TO PASS FAIRLY QUICKLY AND PRECIP WITH IT MAY BE SHORT
LIVED. THIS MAY RESULT IN MINIMAL SNOW ACCUMULATIONS FOR THE
WASATCH FRONT VALLEYS INITIALLY AS PRECIP WITH THE FRONT ONLY
CHANGES OVER TO SNOW RIGHT BEFORE IT ENDS. THERE SHOULD BE A
BETTER CHANCE OF ACCUMULATING VALLEY SNOW WITH THE FRONT AS IT
HEADS SOUTH ALONG THE I-15 CORRIDOR OVERNIGHT WITH THE SOUTHERN
EXTENT REACHING ALMOST TO CEDAR CITY.

UPSTREAM AMPLIFICATION OF THE RIDGE IN THE ERN PAC SHOULD DUMP
THE COLD POOL ALOFT WITH THIS TROF SQUARELY OVER NRN UT LATER SAT
NIGHT INTO SUN. THIS SETS UP A PERIOD OF DEEPLY UNSTABLE MOIST
COLD NORTHWEST FLOW THRU MIDDAY SUN AND SNOW SHOULD REDEVELOP IN
THE NRN VALLEYS WITH SOME ACCUMULATION BY MID MORNING.

LAKE ENHANCEMENT OF THE SNOW SHOWERS COULD ALSO BE A FACTOR WITH
A POTENTIAL FOR SIGNIFICANT ACCUMULATION SOUTHEAST OF THE GSL BY
NOON SUNDAY.

THE NRN MTNS SHOULD DO QUITE WELL IN THIS PATTERN WITH SWLY FLOW
FAVORED AREAS PICKING UP SIGNIFICANT AMOUNTS AHEAD OF THE FRONT
AND NWLY FLOW FAVORED AREAS BEHIND IT. HAVE UPGRADED THE WATCH TO
A WARNING FOR THESE AREAS AND ISSUED AN ADVISORY FOR THE MTN
VALLEYS...THE WASATCH PLATEAU AND WY. THE CENTRAL MTNS COULD GET
ENOUGH TO WARRANT AN ADVISORY BUT THIS DOES NOT HAPPEN UNTIL SAT
NIGHT SO HAVE HELD OFF FOR NOW.

BRIEF SHORT WAVE RIDGING IS FORECAST FOR SUN AFTN INTO SUN EVE
THEN A TRAILING SHORT WAVE TROF SETS OFF ANOTHER ROUND OF PRECIP
FOR THE NORTH LATER SUN NIGHT INTO MON. EXPECT ADDITIONAL
SIGNIFICANT MTN ACCUMULATION AND THE POTENTIAL OF ADDITIONAL
ACCUMULATION IN THE NRN VALLEYS.

WINDS IN THE MTNS SHOULD BE FAIRLY STRONG AHEAD OF AND ALONG THE
COLD FRONT THEN DROP OFF SOMEWHAT BUT PICK UP AGAIN OUT OF THE NNW
SUN NIGHT INTO MON. WINDS SHOULD ALSO BE STRONG FOR A TIME BEHIND
THE FRONT ACROSS THE NW DESERTS.

EVERYTHING WINDS DOWN MON AFTERNOON AS HEIGHTS RISE AND THE
AIRMASS ALOFT WARMS.

&&

.LONG TERM (AFTER 00Z TUESDAY)...DEEP WARM ADVECTION COUPLED WITH
AN INFLUX OF 7H MOISTURE MAY ENABLE A FEW SNOW SHOWERS TO REDEVELOP
IN THE NORTHERN WASATCH MOUNTAINS AND UINTAS TUESDAY
MORNING...POSSIBLY LINGERING INTO THE AFTERNOON. A BUILDING RIDGE
OFF THE CALIFORNIA COAST WILL NUDGE INTO THE GREAT BASIN...OFFERING
THE FINAL DEATH KNELL OF THE STORM SYSTEM. TEMPERATURES STATEWIDE
REBOUND AS THIS RIDGE TRANSLATES THROUGH UTAH MIDWEEK. AT THIS POINT
MODELS SOLUTIONS DIVERGE...THOUGH BOTH THE EC AND GFS SHOW A TROUGH
BRINGING A CHANCE OF PRECIPITATION TO NORTHERN UTAH BY THE END OF
THE WORK WEEK.

&&

.AVIATION...VFR CONDITIONS WILL PERSIST AT THE SLC TERMINAL THROUGH
THE EVENING. LIGHT NORTHWEST WINDS ARE EXPECTED TO SHIFT TO THE
SOUTHEAST BY 03Z. CIGS LOWER AND WINDS INCREASE AFTER MIDNIGHT.
EXPECTING CIGS TO REACH 6000 FT AGL BETWEEN 13-15Z AS RAIN SHOWERS
CREEP CLOSER TO THE TERMINAL. WINDS MAY REACH AIRPORT WIND WARNING
CRITERIA BETWEEN 12Z AND 22Z. THERE IS A 30 PERCENT CHANCE OF
MVFR CONDITIONS WITH VICINITY SHOWERS THROUGHOUT THE MORNING.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER WEATHER ADVISORY FROM 5 AM SATURDAY TO 5 PM MST MONDAY
     FOR UTZ006-010.

     WINTER STORM WARNING FROM 5 AM SATURDAY TO 5 PM MST MONDAY FOR
     UTZ007>009.

WY...WINTER WEATHER ADVISORY FROM 8 AM SATURDAY TO 9 AM MST SUNDAY
     FOR WYZ021.

&&

$$

SHORT TERM...WILENSKY
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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