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FXUS65 KSLC 092054
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
254 PM MDT THU SEP 9 2010
.SYNOPSIS...A COOL PACIFIC TROUGH WILL LIFT THROUGH THE STATE
THROUGH FRIDAY MORNING. HIGH PRESSURE WILL BUILD THROUGH THE
WEEKEND WITH DRIER WESTERLY FLOW DOMINATING THROUGH MIDWEEK OF
NEXT WEEK.
&&
.DISCUSSION...AFTERNOON SATELLITE LOOPS SHOW PACIFIC TROUGH
LIFTING NORTHEAST THROUGH THE GREAT BASIN/NORTHERN ROCKIES STATES.
SAID TROUGH EXHIBITS TWO PRONOUNCED SHORT WAVES...WITH FIRST
LIFTING THROUGH CENTRAL IDAHO...AND A TRAILING COLD POCKET
DROPPING SOUTHEAST THROUGH EASTERN OREGON. INITIAL WAVE WAS
RESPONSIBLE FOR SURGING THE LEADING EDGE COLD FRONT THROUGH THE
WASATCH FRONT THIS MORNING SPREADING NUMEROUS SHOWERS AND STORMS
ACROSS THE METRO AREA. THE FRONT CURRENTLY REMAINS STALLED ACROSS
SOUTHERN UTAH VALLEY WITH DRY AND GUSTY SOUTHWESTERLY FLOW
DOMINATING CENTRAL AND SOUTHERN PORTIONS OF THE STATE. STALLED
NATURE OF THE FRONT HAS ALLOWED FOR A SUBSIDENT AIRMASS ACROSS THE
CENTRAL WASATCH...SQUELCHING MOST ALL AFTERNOON SHOWER DEVELOPMENT
SOUTH OF OGDEN. AREAS NORTH OF OGDEN REMAIN MORE BUOYANT AS MID
LEVEL BAROCLINIC ZONE PASSES THROUGH THE EAST. SCATTERED SHOWERS
AND ISOLATED STORMS REMAINING ALONG THE UT/ID BORDER.
AFOREMENTIONED UPSTREAM SHORT WAVE WILL CARVE THE TROUGH SOUTH A
BIT AFTER MIDNIGHT TONIGHT...SURGING THE STALLED SURFACE BOUNDARY
INTO SOUTH CENTRAL UTAH BY DAWN FRIDAY. MODEL SUITE CONSISTENT IN
REGENERATING PRECIP ACROSS THE WASATCH FRONT/MOUNTAINS AS THIS
OCCURS...WITH SHOWERS AND EVEN SOME SNOW POSSIBLE ACROSS THE
CENTRAL/NORTHERN WASATCH MOUNTAINS ABOVE 75-8000 FT EARLY FRIDAY
MORNING. THIS IDEA SEEMS REALISTIC. SUBSIDENCE WILL WANE ACROSS
THE NORTH AS FRONTAL BOUNDARY FINALLY TRACKS SOUTH...AND MID LEVEL
COLD POCKET WILL ALLOW WEAK COLD ADVECTION INCREASING INSTABILITY
ACROSS THE NORTH. PVA ASSOCIATED WITH UPSTREAM SHORT WAVE TO
INITIATE SHOWERS. KEPT SCATTERED TO NUMEROUS SHOWERS IN FORECAST
FOR LATE NIGHT WITH MUCH COOLER TEMPS.
CLEARING AND DRYING CONDITIONS EXPECTED ALL AREAS BY MIDDAY
FRIDAY. PACIFIC TROUGH WILL LIFT OFF RAPIDLY TO THE NORTHEAST
ALLOWING RAPID HEIGHT RISES AS SHORT WAVE RIDGING ENTRENCHES IN
THE GREAT BASIN STARTING FRIDAY NIGHT. ANOTHER COOL NIGHT EXPECTED
FRIDAY NIGHT AS A RESULT...ESPECIALLY FOR MOUNTAIN VALLEY AREAS.
ADDED MENTION OF PATCHY FROST THROUGH THE BEAR RIVER VALLEY AND
WASATCH BACK.
AFOREMENTIONED RIDGE WILL HOLD STRONG THROUGH EARLY NEXT WEEK. TEMP
TRENDS TO CLIMB RAPIDLY BACK TOWARDS CLIMO...EXCEEDING NORMS BY EARLY
NEXT WEEK IN SOME LOCALS.
&&
.AVIATION...THERE IS A 30 PERCENT CHANCE OF SHOWERS IMPACTING THE
SLC TERMINAL THROUGH THE EVENING AND OVERNIGHT HOURS...WITH CEILINGS
BELOW 7000FT AGL POSSIBLE IN ANY SHOWERS. GUSTY NORTHWEST SURFACE
WINDS ARE EXPECTED TO WEAKEN THROUGH THE EVENING...THEN RETURN TO
THE SOUTH BETWEEN 04Z AND 06Z...WITH A SLIGHT CHANCE THAT WINDS
REMAIN NORTHWESTERLY THROUGH 07Z.
&&
.FIRE WEATHER...THE PACIFIC TROUGH CONTINUES TO MOVE THROUGH
NORTHERN UTAH AND IS PULLING OFF TO THE NORTHEAST. THE ASSOCIATED
COLD FRONT HAS PUSHED INTO CENTRAL UTAH AND WILL MAKE LITTLE FARTHER
PROGRESS SOUTH. SHOWERS AND THUNDERSTORMS WILL CONTINUE THIS
AFTERNOON AND EVENING WITH ANOTHER FAIR SHOT FOR NOCTURNAL
CONVECTION FRIDAY MORNING WHEN THE COLDEST AIR AND ANOTHER WEAK WAVE
ARRIVES OVER THE NORTHERN PORTION OF THE FIRE DISTRICT. MUCH COOLER
TEMPERATURES ALONG WITH WETTING RAINS CAN BE EXPECTED THROUGH FRIDAY
MORNING OVER THE NORTH. AHEAD OF THIS FRONT...OVER THE SOUTHERN HALF
OF THE DISTRICT...GUSTY SOUTHWEST WINDS ALONG WITH MILD TEMPERATURES
CAN BE EXPECTED TONIGHT AND FRIDAY. ISOLATED CRITICAL FIRE WEATHER
CONDITIONS POSSIBLE ACROSS SOUTHEAST UTAH...BUT ONLY BORDERLINE WITH
NO WARNINGS ANTICIPATED. WINDS WILL CONTINUE TO RELAX OVER THE NEXT
SEVERAL DAYS AS A RIDGE OF HIGH PRESSURE SETTLES OVER THE AREA. THIS
WILL USHER IN A DRY AND MILD WESTERLY FLOW AND A WARMING AND DRYING
TREND THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK.
&&
.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...NONE.
&&
$$
PUBLIC...MERRILL
FIRE WEATHER...YOUNG
AVIATION...SCHOENING
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