Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 030248
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
848 PM MDT WED SEP 2 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH OVER WESTERN CANADA WILL SETTLE
INTO THE PACIFIC NORTHWEST LATE THIS WEEK...THEN SWING EAST ACROSS
THE GREAT BASIN AND NORTHERN ROCKIES THIS WEEKEND. MILD
SOUTHWESTERLY FLOW WILL PREVAIL AHEAD OF THIS TROUGH THROUGH THE
REMAINDER OF THE WEEK...WITH COOL FALL LIKE TEMPERATURES ARRIVING
OVER THE LABOR DAY WEEKEND.

&&

.DISCUSSION...THE FORECAST AREA REMAINS UNDER A BREEZY SOUTHWEST
FLOW THIS EVENING BETWEEN THE RIDGE OVER THE CENTRAL UNITED STATES
AND THE BROAD TROUGH APPROACHING THE PACIFIC NORTHWEST COAST. THE
AIRMASS DRIED CONSIDERABLY TODAY AND BECAUSE OF THIS CONVECTION
WAS MUCH MORE ISOLATED THAN IT HAD BEEN PREVIOUS DAYS. ANY
RESIDUAL STORMS HAVE DISSIPATED WITH THE LOSS OF DAYTIME HEATING.
SOME WIND GUSTS IN THE 30-40 KT RANGE HAVE BEEN OBSERVED
TODAY...BUT RIGHT NOW MOST OBSERVED GUSTS REMAIN IN THE 15-25 KT
RANGE.

MODELS INDICATE THAT THE SOUTHWEST FLOW WILL BRING SOME MOISTURE
BACK INTO THE SOUTHWEST UNITED STATES TOMORROW. THE EC KEEPS THIS
MOISTURE SURGE PRIMARILY OVER ARIZONA...NEW MEXICO...AND COLORADO.
HOWEVER...GFS AND NAM HAVE BEEN CONSISTENT IN BRINGING SOME OF
THIS MOISTURE INTO EASTERN UTAH. THIS MOISTURE WOULD BRING AN
INCREASED THREAT OF SHOWERS AND THUNDERSTORMS TOMORROW AND FRIDAY
OVER THE EAST. AS THE PACIFIC NORTHWEST TROUGH INCHES
EASTWARD...FLOW ALOFT OVER THE CWA WILL CONTINUE TO
INCREASE...ESPECIALLY OVER WESTERN UTAH. LATEST GFS INDICATES
WIDESPREAD AREAS OF 30 KT 700 MB FLOW...WITH UP TO 50 KTS FRIDAY
NIGHT/SATURDAY MORNING.

THE TROUGH IS PROGGED TO DIG SOUTHWARD INTO CALIFORNIA AND NEVADA
FRIDAY THROUGH SATURDAY MORNING BEFORE SWEEPING EASTWARD THROUGH
NORTHERN UTAH SATURDAY AFTERNOON THROUGH SATURDAY NIGHT...A BIT
FASTER THAN WHAT GUIDANCE WAS INDICATING AT THIS TIME YESTERDAY.
THE PASSAGE OF THE TROUGH WILL PUSH A SIGNIFICANT COLD FRONT INTO
NORTHERN AND CENTRAL UTAH. THE FRONTAL PASSAGE SHOULD BE MOSTLY
DRY BUT WILL COOL TEMPERATURES SIGNIFICANTLY...WITH 700 MB TEMPS
DROPPING FROM UP TO +12C FRIDAY AFTERNOON TO AS LOW AS +1C OR +2C
OVER NORTHERN UTAH SATURDAY AFTERNOON. BY SUNDAY...MAXES OVER
NORTHERN UTAH ARE PROGGED TO BE UP TO 15F BELOW SEASONAL NORMALS.
HOWEVER...A DRIER SOUTHWEST FLOW BEHIND THE EXITING TROUGH WILL
ALLOW TEMPERATURES TO WARM QUICKLY OVER UTAH AND SOUTHWEST WYOMING
FOR EARLY NEXT WEEK.

NO UPDATES EXPECTED TO THE FORECAST THIS EVENING.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGH THE
NIGHT WITH SOME HIGH CLOUDS. SOUTHERLY WINDS ARE EXPECTED THROUGH
THE OVERNIGHT HOURS...BECOMING GUSTY AT TIMES DURING THE EARLY
MORNING.

&&

.FIRE WEATHER...A DEVELOPING TROUGH ALONG THE WEST COAST WILL
RESULT IN AN INCREASE IN SOUTHWESTERLY FLOW THROUGH THE REMAINDER
OF THE WEEK. THIS WILL RESULT IN BREEZY TO WINDY CONDITIONS ACROSS
THE WESTERN HALF OF THE AREA THURSDAY INTO FRIDAY. IN ADDITION TO
THE GUSTY WINDS...HUMIDITY VALUES ARE EXPECTED TO FALL BELOW 15
PERCENT EACH AFTERNOON WITH POOR OVERNIGHT RECOVERIES. FURTHER
EAST...MOISTURE IS EXPECTED TO INCREASE ACROSS THE EASTERN HALF
OF UTAH THURSDAY INTO FRIDAY BRINGING A RETURN OF SHOWERS AND
THUNDERSTORMS. THE UPSTREAM TROUGH IS FORECAST TO SWING THROUGH
THE REGION SATURDAY BRINGING A CHANCE FOR PRECIPITATION TO
NORTHERN AND CENTRAL UTAH. WINDS WILL ALSO REMAIN ELEVATED ACROSS
MOST VALLEYS THROUGH THE DAY SATURDAY. A MUCH COOLER AIRMASS WILL
FOLLOW THIS SYSTEM FOR SUNDAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...RED FLAG WARNING UNTIL 9 PM FRIDAY FOR WYZ277.

&&

$$

TRAPHAGAN/SEAMAN

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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