Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 011104
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
504 AM MDT SAT NOV 1 2014

.SYNOPSIS...A COLD AND ENERGETIC PACIFIC STORM SYSTEM WILL MOVE
INTO UTAH TODAY. COOL AND UNSETTLED WEATHER WILL REMAIN OVER THE
AREA SATURDAY NIGHT THROUGH EARLY MONDAY.

&&

.DISCUSSION...THE UPPER LEVEL TROUGH CURRENTLY CENTERED ACROSS THE
WEST COAST STATES WILL TRACK EAST INTO THE GREAT BASIN LATER
TODAY. THIS TROUGH WILL LINGER OVER THE REGION THROUGH SUNDAY
NIGHT...THEN EXIT TO THE EAST DURING THE DAY MONDAY.

A WELL-DEFINED VORTICITY CURRENTLY OVER SOUTHERN CALIFORNIA WILL
LIFT QUICKLY TO THE NORTHEAST THROUGH NEVADA AND INTO WESTERN
UTAH LATER THIS MORNING. THE ASSOCIATED COLD FRONT WILL SURGE EAST
INTO THE STATE MID-MORNING AS THE MID-LEVEL DYNAMIC FEATURE
ADVANCES THROUGH NEVADA.

THIS FRONT SHOULD BE THE FOCUS FOR ACTIVE AND STRONG CONVECTION
TODAY. ALL THE INGREDIENTS NECESSARY FOR DEEP CONVECTION APPEAR TO
BE IN PLACE. INCREASING LOW-LEVEL COLD ADVECTION WITH FAIRLY RAPID
MID-LEVEL COOLING WILL QUICKLY DESTABLIZE THE AIRMASS THIS
MORNING. ADEQUATE MOISTURE...STRONG DYNAMIC LIFT AND GOOD UPPER
DIVERGENCE IN THE EXIT REGION OF THE JET ALONG THE NORTHEAST FLANK
OF THE VORTICITY MAX WILL COMBINE WITH THE FAVORABLE THERMAL
STRUCTURE TO GENERATE STRONG CONVECTION ACROSS WEST-CENTRAL
THROUGH NORTHERN UTAH DURING THE LATE MORNING AND AFTERNOON.

THE DEEPENING SURFACE LOW OVER NORTHEAST NEVADA COMBINED WITH
STRONG NEAR 700MB WINDS HAS ALREADY GENERATED VERY STRONG
SOUTHERLY WINDS ACROSS SOUTHWEST AND WEST-CENTRAL UTAH. WIND
REPORTS SO FAR ARE APPROACHING HIGH WIND CRITERIA...AND SHOULD HIT
THE MARK IN A FEW AREAS EARLY THIS MORNING. SOMEWHAT CONCERNED
THAT HIGH WINDS WILL TAPER OFF A BIT SOONER THAN EXPECTED AS
CONVECTION RAPIDLY INCREASES TODAY. ONE CAVEAT WOULD BE THE
POTENTIAL FOR CONVECTIVE HIGH WINDS DUE TO DOWNWARD MOMENTUM
TRANSFER IN THE STRONG CONVECTIVE CELLS.

LOWERING SNOW LEVELS BEHIND THE COLD FRONT WILL QUICKLY TURN
PRECIP TO SNOW AT THE HIGHER ELEVATIONS. THE RELATIVELY BRIEF
CONVECTIVE BURST TODAY WILL PROBABLY NOT GENERATE MUCH
ACCUMULATION THROUGH THIS AFTERNOON. THE BEST CHANCE FOR
SIGNIFICANT ACCUMULATIONS WILL COME AS THE UPPER TROUGH STRETCHES
OUT ACROSS THE GREAT BASIN TONIGHT THROUGH SUNDAY NIGHT.

THE MOIST AND FAIRLY UNSTABLE AIR MASS WITHIN THE TROUGH WILL
CONTINUE PRODUCE PRECIP THROUGH EARLY MONDAY. A COUPLE OF AREAS
OF INTEREST WILL EXIST WHICH COULD GENERATE SUBSTANTIAL SNOWFALL.
ONE SUCH AREA WILL BE ALONG THE OLD BAROCLINIC ZONE WHICH WILL
STRETCH SOUTHWEST TO NORTHEAST THROUGH THE MIDDLE OF THE STATE.
CONVERGENCE INTO THIS BOUNDARY CREATED FROM THE RESIDUAL
CIRCULATION IN THE SOUTHERN END OF THE TROUGH SHOULD MAINTAIN A
FAIRLY STEADY PERIOD OF PRECIP THROUGH THE BALANCE OF THE WEEKEND.

A SECOND POTENTIAL AREA FOR SIGNIFICANT PRECIP WILL COME LATE IN
THE WEEKEND AS THE MAIN TROUGH AXIS SLOWLY WORKS EAST ACROSS
NORTHERN UTAH. FURTHER DESTABLIZATION OF THE AIR MASS IS EXPECTED
AS THE COLDEST AIR ALOFT MOVES ACROSS THE AREA WITH THE TROUGH.
WEAK DYNAMIC LIFT WORKING ON THIS AIR MASS SHOULD BE ABLE TO
GENERATE ANOTHER ROUND OF WIDESPREAD SNOW IN THE MOUNTAINS...WITH
RAIN AND OR SNOW EXTENDING DOWN INTO THE ADJACENT VALLEYS. THE
CURRENT WINTER WEATHER ADVISORY MAY HAVE TO BE EXTENDED TO ACCOUNT
FOR THIS ADDITIONAL SNOW THROUGH THE BALANCE OF THE WEEKEND.

LINGER SHOWERS EARLY MONDAY WILL WIND DOWN FAIRLY QUICKLY LATE IN
THE DAY AS THE UPPER TROUGH MOVES EAST OF THE FORECAST AREA. THE
STABLE ANTI-CYCLONIC NORTHWEST FLOW AHEAD OF AN ADVANCING UPPER
RIDGE WILL BRING DRY CONDITIONS AND A GRADUAL WARMING TREND
THROUGH THE EXTENDED FORECAST PERIOD.


&&

.AVIATION...LIGHT AND VARIABLE SURFACE WINDS CURRENTLY AT THE KSLC
TERMINAL WILL INCREASE RAPIDLY FROM THE SOUTH BETWEEN 11-13Z...WITH
GUSTS WELL IN EXCESS OF 30 MPH DEVELOPING BETWEEN 15-16Z. PERIODIC
GUSTS IN THE 40 TO 50 MPH RANGE ARE EXPECTED LATE MORNING THROUGH
THE AFTERNOON WITH DIRECTIONS TRENDING FROM SOUTHEAST TO SOUTHWEST.
INTERMITTENT SHOWERS WILL DEVELOP THIS AFTERNOON AS WELL BUT CIGS
ARE EXPECTED TO REMAIN ABOVE 6000FT AGL THROUGH THE DAYLIGHT HOURS.
THIS SAID...A 10 PERCENT CHANCE EXISTS FOR A THUNDERSTORM TO IMPACT
THE TERMINAL AFTER 20Z.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER WEATHER ADVISORY UNTIL 10 PM MDT THIS EVENING FOR
     UTZ007>010-517-518.

     WIND ADVISORY UNTIL 10 PM MDT THIS EVENING FOR UTZ001-002-004-
     006-014.

     HIGH WIND WARNING UNTIL 10 PM MDT THIS EVENING FOR UTZ003-005-
     015-016.

WY...NONE.
&&

$$

PUBLIC...CONGER
AVIATION...MERRILL

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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