Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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FXUS65 KSLC 242223
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
423 PM MDT FRI OCT 24 2014

.SYNOPSIS...A COLD FRONT APPROACHING UTAH WILL GENERATE STRONG
SOUTHERLY WINDS ON SATURDAY. MUCH COLDER TEMPERATURES WILL SPREAD
ACROSS THE STATE FOR SUNDAY AND MONDAY WITH AREAS OF VALLEY RAIN
AND MOUNTAIN SNOW FOR FAR NORTHERN UTAH AND SOUTHWEST WYOMING.

&&

.SHORT TERM (UNTIL 00Z TUESDAY)...HIGH PRESSURE ALOFT OVER THE
REGION THIS AFTERNOON WILL MOVE EAST INTO THE PLAINS STATES BY
SATURDAY. THE NEXT PACIFIC TROUGH CURRENTLY POSITIONED JUST WEST
OF 130W WILL REACH THE WEST COAST SATURDAY MORNING...THEN TRACK
EAST-NORTHEAST THROUGH THE NORTHERN ROCKIES/NORTHERN GREAT BASIN
OVER THE WEEKEND.

WINDS APPEAR TO BE THE PRIMARY ISSUE WITH THIS APPROACHING TROUGH.
THE ASSOCIATED SURFACE COLD FRONT WILL CROSS NEVADA SATURDAY
AFTERNOON WITH FAIRLY STRONG SUPPORTING NEAR 700MB WINDS OVER UTAH
AHEAD OF THE FRONT. GOOD MIXING AHEAD OF THE FRONT ALONG WITH THE
FAVORABLE SURFACE GRADIENT WILL GENERATE STRONG SOUTHERLY WINDS
ACROSS THE WESTERN VALLEYS SATURDAY AFTERNOON/EVENING. HAVE ISSUED
A WIND ADVISORY FOR MOST OF THE WESTERN VALLEYS FOR SATURDAY
AFTERNOON AND EVENING. THIS ADVISORY MAY HAVE TO BE EXTENDED INTO
THE POST-FRONTAL ENVIRONMENT. INCREASING LOW-LEVEL COLD ADVECTION
BEHIND THE FRONT WILL SERVE TO TIGHTEN THE SURFACE GRADIENT...WITH
STRONG NORTHWEST WINDS POSSIBLE ACROSS THE NORTHWEST DESERTS AND
IN THE DOWNSLOPE WIND AREAS OF THE WESTERN UINTA BASIN AND THE SAN
RAFAEL SWELL IN EAST-CENTRAL UTAH.

GLOBAL MODELS THE PAST SEVERAL RUNS HAVE BEEN TRENDING FURTHER
NORTH WITH THE TRACK OF THE TROUGH AND THE ASSOCIATED COLD AIR.
THE FIRST THREAT FOR PRECIP WILL COME FROM A SHORTWAVE EJECTING
OUT AHEAD OF THE MAIN TROUGH SATURDAY NIGHT. THIS FEATURE WILL
SERVE TO PUSH THE ASSOCIATED COLD FRONT INTO NORTHWEST UTAH DURING
THE NIGHT. WEAK DYNAMIC LIFT FROM THIS FEATURE COMBINED WITH SOME
INSTABILITY FROM THE POCKET OF COOLER MID-LEVEL AIR SHOULD FORM
SHOWERS/ISOLATED THUNDERSTORMS NEAR THE IDAHO BORDER.

THE BEST CHANCE AT PRECIP WILL COME SUNDAY AFTERNOON/EVENING AS
THE MAIN TROUGH MOVES INTO THE NORTHERN ROCKIES/NORTHERN GREAT
BASIN. STRONG LOW-LEVEL COLD ADVECTION WITH ADDITIONAL COOLING IN
THE SOUTH END OF THE TROUGH SHOULD SPAWN ADDITIONAL SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS THE NORTHERN QUARTER OF THE FORECAST
AREA. TEMPERATURES ALOFT WILL BE SUFFICIENTLY COLD TO GENERATE
SNOW IN THE MOUNTAINS. ACCUMULATIONS ARE LIKELY...THOUGH AMOUNTS
WILL GENERALLY REMAIN LIGHT. THE FAR NORTHERN VALLEYS COULD SEE
SOME SNOW MIX IN WITH ANY RAIN IN THE MORE INTENSE CONVECTIVE
ELEMENTS.

INSTABILITY SHOWERS WILL LINGER ACROSS THE NORTH LATE SUNDAY NIGHT
AND INTO EARLY MONDAY MORNING. RAPID MID-LEVEL WARMING ON MONDAY
SHOULD BRING A QUICK END TO MOST OF THE REMAINING SHOWERS BY LATE
MONDAY MORNING OR EARLY AFTERNOON. THE COLD TEMPERATURES ON SUNDAY
WILL CONTINUE OR EVEN COOL FURTHER ON MONDAY.

&&

.LONG TERM (AFTER 00Z TUESDAY)...AFTER THE TROUGH EXITS THE REGION
THROUGH THE LATTER HALF OF MONDAY...SKIES ARE EXPECTED TO CLEAR
OVERNIGHT...LEADING TO PERHAPS THE COLDEST NIGHT OF THE SEASON THUS
FAR IN MANY OF UTAHS VALLEYS AND BASINS. WARM ADVECTION AND WEAK
RIDGING ALOFT ARE FORECAST TO INCREASE OVER THE AREA TUESDAY...BUT
WARMING WILL LIKELY BE A SLOW PROCESS IN THE VALLEYS.

LATE TUESDAY THROUGH WEDNESDAY...A WEAK SHORTWAVE IS PROGGED TO
BRUSH THE NORTHERN FRINGES OF THE CWA IN THE NORTHWESTERLY FLOW.
HAVE KEPT A SLIGHT CHANCE OF SHOWERS ALONG THE UTAH/IDAHO BORDER
THROUGH THIS PERIOD...AND INCREASED CLOUD COVER ACROSS THE NORTH.
HAVE KEPT TEMPERATURES NEAR SEASONAL NORMALS THROUGH MID-
WEEK...WITH A SLOW WARMING TREND.

WEDNESDAY NIGHT AND THURSDAY...THE RIDGE THAT HAD BEEN LINGERING
OVER SOUTHERN CALIFORNIA IS FORECAST TO AMPLIFY AND SHIFT OVER THE
INTERMOUNTAIN WEST...HELPING RETURN THE AREA TO WARMER THAN SEASONAL
TEMPERATURES THROUGH THE REST OF THE WEEK. THERE IS A CHANCE WARMING
COULD BE ENHANCED EVEN MORE FRIDAY AND SATURDAY...AS SOUTHWESTERLY
FLOW BEGINS TO INCREASE A BIT EAST OF THE NEXT PACIFIC TROUGH OVER
THE WEST COAST.

&&

.AVIATION...WINDS AT THE SLC TERMINAL ARE EXPECTED TO SWITCH BACK TO
THE NORTHWEST BETWEEN 22Z AND 23Z...WITH A 30 PERCENT CHANCE THAT
SOUTHERLIES PERSIST THROUGH THE REST OF THE AFTERNOON AND EARLY
EVENING. A PREVAILING SOUTH-SOUTHEAST SHOULD DEVELOP BETWEEN 02Z
AND 03Z. VFR CONDITIONS UNDER CLEAR SKIES WILL EXIST OVERNIGHT.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WIND ADVISORY FROM NOON SATURDAY TO MIDNIGHT MDT SATURDAY NIGHT
     FOR UTZ005-015-016.

WY...NONE.
&&

$$

SHORT TERM...CONGER
LONG TERM/AVIATION...SCHOENING

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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