Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 221214
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
514 AM MST SAT NOV 22 2014

.SYNOPSIS...A COLD AND ENERGETIC STORM SYSTEM WILL REACH UTAH BY
LATE THIS AFTERNOON. THIS STORM WILL IMPACT MAINLY NORTHERN AND
CENTRAL UTAH THROUGH THE WEEKEND. A TRAILING WEATHER DISTURBANCE
WILL CROSS UTAH MONDAY.

&&

.SHORT TERM (UNTIL 00Z WEDNESDAY)...THE UPPER LEVEL TROUGH
EMBEDDED WITH THE STRONG MID-LATITUDE WESTERLIES WILL REACH THE
PACIFIC NORTHWEST COAST EARLY THIS MORNING. THIS FEATURE DRIVEN BY
THE 160+ KT JET WILL MOVE QUICKLY INTO THE NORTHERN ROCKIES AND
GREAT BASIN BY LATE THIS AFTERNOON. THIS TROUGH WILL USHER IN AN
EXTENDED PERIOD OF UNSETTLED WEATHER THIS WEEKEND.

STRONG AND INCREASINGLY MOIST LOW-LEVEL WARM ADVECTION WILL BRING
LIGHT PRECIP TO FAR NORTHERN UTAH THIS MORNING. SNOW-LEVELS SHOULD
REMAIN FAIRLY HIGH THIS MORNING AS NEAR 700MB TEMPS HOVER JUST
SLIGHTLY BELOW THE FREEZING MARK. HIGHER VALLEY LOCATIONS HAVE
BEEN MIXING OUT OVERNIGHT...SO WILL KEEP THE PRECIP TYPE
PREDOMINATELY AS RAIN THROUGH AT LEAST EARLY AFTERNOON.

THE 06Z NAM/GFS HAVE CONTINUED THE IDEA OF COLDER MID-LEVEL AIR
MOVING OVER THE TOP OF THE LOW-LEVEL WARM ADVECTION BEGINNING LATE
THIS MORNING. THE RESULT OF THIS WILL BE TO CREATE A DEEPER LAYER
OF INSTABILITY AND STRONGER LIFT HEADING INTO THIS AFTERNOON.
SNOW LEVELS WILL BEGIN TO LOWER DUE TO THE MORE INTENSE
PRECIP...THOUGH THE LOWER VALLEYS WILL LIKELY STAY IN RAIN THROUGH
MID-AFTERNOON.

THE COLD FRONT ASSOCIATED WITH THE ADVANCING TROUGH WILL MOVE OUT
OF THE PACIFIC NORTHWEST AND INTO NORTHWEST UTAH BY AROUND MID-
AFTERNOON. STRONG LOW-LEVEL FRONTOGENIC FORCING IDENTIFIED BY THE
GUIDANCE AS THE FRONT MOVES INTO NORTHWEST UTAH COULD SIGNAL A
BRIEF PERIOD OF CONVECTION LATE THIS AFTERNOON. THE NAM PLACES
THIS THREAT CLOSER TO THE NORTHERN/CENTRAL WASATCH FRONT...WHILE
THE GFS SHIFTS FURTHER SOUTH ACROSS THE CENTRAL/SOUTHERN WASATCH
FRONT. IN EITHER CASE SIGNIFICANTLY COLDER AIR WILL SURGE SOUTH
THROUGH THE REGION...DRIVING SNOW-LEVELS MUCH LOWER LATE THIS
AFTERNOON AND EVENING. PERIODS OF HEAVY SNOW WILL EXIST DUE TO THE
COLD TEMPS AND STRONG DYNAMIC/THERMALLY DRIVEN LIFT THROUGH EARLY
SUNDAY.

DUE TO THE RAPIDLY STRENGTHENING COLD FRONT AND THE STRONG
NEAR 700MB SUPPORTING NORTHWEST WINDS...HAVE ADDED A WIND ADVISORY
TO THE GREAT SALT LAKE DESERT AND MOUNTAINS IN NORTHWEST UTAH FOR
THIS AFTERNOON THROUGH AROUND MIDNIGHT TONIGHT.

SHORTWAVE RIDGING SUNDAY AFTERNOON WILL BRING A BRIEF LULL IN SNOW
EXTENDING INTO EARLY SUNDAY EVENING. A SECOND TRAILING SHORTWAVE
WILL RE-ENERGIZE SNOW IN THE COLD/MOIST AND STILL UNSTABLE AIR
MASS OVER THE NORTHERN HALF OF THE STATE. OROGRAPHIC INFLUENCES
WILL ALSO BE IN PLAY...LEADING TO THE POTENTIAL FOR HEAVY SNOW
AGAIN IN THE WASATCH RANGE AND THE ADJACENT WINDWARD VALLEYS. CAN
NOT RULE OUT LAKE EFFECT SNOWS DOWNWIND OF THE GSL...AND POSSIBLY
UTAH LAKE LATE SUNDAY NIGHT THROUGH EARLY MONDAY.

THE UPPER RIDGE BUILDING OVER THE EASTERN PACIFIC BEGINNING LATE
SUNDAY WILL EVENTUALLY PRODUCE A STABLE NORTH-NORTHWEST FLOW
ACROSS THE INTERIOR WEST STARTING MONDAY NIGHT. THIS RIDGE WILL BE
THE DOMINANT FEATURE THROUGH TUESDAY AND BEYOND.

&&

.LONG TERM (AFTER 00Z WEDNESDAY)...BOTH THE EC AND GFS SHOW
SOME WEAK WARM 700MB ADVECTION ACROSS THE NORTHERN UTAH MOUNTAINS
BETWEEN 00Z AND 12Z WEDNESDAY SO HAVE KEPT THE MINIMAL POPS. AFTER
THAT THE RIDGE STRENGTHENS FOR WEDNESDAY THROUGH FRIDAY...MORE SO BY
THE EC THAN THE GFS. TEMPERATURES WILL BE CHALLENGING DUE TO SOME
AREAS POSSIBLY UNDER A SNOW COVER WELL INTO THE WEEK. HAVE GONE WITH
50 AT SLC BY WEDNESDAY...WHICH IS ABOUT THE MEAN OF THE VARIOUS
MODEL SOLUTIONS. THIS TEMP COULD BE ON THE WARM SIDE IF EXTENSIVE
SNOW COVER REMAINS IN PLACE. TEMPERATURES SHOULD CONTINUE TO INCH
UPWARDS AS THE H7 TEMPS CLIMB A COUPLE MORE DEGREES CELSIUS THROUGH
FRIDAY. THE EC APPEARS TO BE TOO STRONG ON THIS WARMING SO KEPT
CLOSER TO THE GFS.

BY LATE FRIDAY THE EC INDICATES A WEAK SHORTWAVE BREAKING UNDERNEATH
THE WEST COAST RIDGE AHEAD OF WHEN THE GFS BREAKS A SHORT WAVE
THROUGH. WILL LEAN TOWARDS THE SLOWER GFS SOLUTION AND THEREFORE
HOLD OFF ON ANY CHANCES OF PRECIP UNTIL SATURDAY NIGHT WHEN THE GFS
BRINGS A WEAK TROUGH ACROSS THE GREAT BASIN. DUE TO THE BROAD
WEAKNESS OF THIS TROUGH...HAVE UNDERCUT CLIMO POPS FOR THIS TIME
FRAME BUT STILL LEFT SLIGHT CHANCE IN MOST MOUNTAINS. TEMPERATURES
SHOULD BE RATHER MILD DURING THE END OF THE WEEK.


&&

.AVIATION...SOUTH WINDS WILL INCREASE AT THE SLC TERMINAL THROUGH
EARLY AFTERNOON BEFORE SHIFTING TO THE NORTHWEST BETWEEN 23 AND 24Z.
CIGS ARE EXPECTED TO REMAIN ABOVE 7K FT AGL UNTIL THE WIND
SHIFT/COLD FRONT...ALTHOUGH THERE IS A 30 PERCENT CHANCE OF CIGS
BELOW 7KT AFTER ABOUT 22Z. THERE IS A GOOD CHANCE THAT VLIFR
CONDITIONS COULD OCCUR BETWEEN 01 AND 03Z IN SNOW AND LOW CIGS.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER WEATHER ADVISORY UNTIL 5 PM MST MONDAY FOR UTZ006-010.

     WINTER STORM WARNING UNTIL 5 PM MST MONDAY FOR UTZ007>009.

     WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 2 AM MST SUNDAY FOR
     UTZ005.

     WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 6 PM MST
     SUNDAY FOR UTZ517.

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

&&

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...STRUTHWOLF

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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