Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 021639
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1039 AM 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...MILD SOUTHWESTERLY FLOW WILL PREVAIL ACROSS THE
FORECAST AREA TODAY...DOWNSTREAM FROM A DEEPENING UPPER TROUGH
ALONG THE WEST COAST. ONCE AGAIN BREEZY SOUTHERLY WINDS ARE
EXPECTED ACROSS THE WESTERN VALLEYS THIS AFTERNOON AS HIGHER
MOMENTUM MIXES DOWN TO THE SURFACE. GOES PW IMAGERY AND 12Z
SOUNDINGS INDICATE THE AIRMASS HAS DRIED SLIGHTLY OVER THE LAST 24
HOURS...HOWEVER LINGERING MOISTURE WILL LIKELY ALLOW FOR AT LEAST
ISOLATED CONVECTION OVER THE HIGHER TERRAIN THIS
AFTERNOON...BEFORE WORKING ITS WAY OFF THE TERRAIN AND INTO THE
EASTERN VALLEYS. AN ISOLATED HEAVY RAINER OR TWO IS POSSIBLE...AND
UPDATED THE FORECAST TO INCLUDE SLIGHT CHANCE POPS ACROSS THE
EASTERN VALLEYS DURING THE AFTERNOON HOURS.

OF ADDITIONAL NOTE IS A PLUME OF MID LEVEL MOISTURE WORKING ITS
WAY NORTHWARD ACROSS EASTERN NV AND WEST CENTRAL UT. THIS MAY
PROVE SUFFICIENT FOR HIGH BASED CONVECTION ACROSS EASTERN NV THIS
AFTERNOON...EVENTUALLY SPREADING INTO NORTHWEST UT THIS EVENING.
GIVEN THE DEEPLY MIXED BOUNDARY LAYER IN PLACE GUSTY MICROBURST
WINDS WOULD BE THE MAIN THREAT WITH THIS ACTIVITY.

AS THIS TROUGH DEEPENS THURSDAY INTO FRIDAY SOUTHWESTERLY FLOW
WILL CONTINUE TO GRADUALLY INCREASE ACROSS WESTERN UT...RESULTING
IN BREEZY TO LOCALLY WINDY CONDITIONS. ADDITIONALLY THIS FLOW WILL
TAP INTO DEEPER MOISTURE TO THE SOUTH...WHICH WILL BE ADVECTED
NORTHWARD LATE IN THE WEEK. THE MODELS HAVE STRUGGLED WITH RESPECT
TO THE TIMING AND TRAJECTORY OF THIS MOISTURE SURGE...HOWEVER IT
APPEARS MOISTURE SHOULD REACH AT LEAST SOUTHEAST UT LATE IN THE
DAY THURSDAY...AND REMAIN IN PLACE ACROSS THE EASTERN HALF OF UTAH
THROUGH FRIDAY.

THE UPSTREAM TROUGH IS FORECAST TO EJECT ACROSS THE NORTHERN GREAT
BASIN SATURDAY BRINGING A BETTER CHANCE FOR PRECIPITATION TO
NORTHERN UT. A MUCH COOLER AIRMASS WILL FOLLOW IN THE WAKE OF THIS
TROUGH FOR SUNDAY...WITH MAX TEMPERATURES STRUGGLING TO REACH THE
70F MARK ALONG THE WASATCH FRONT.

&&

.AVIATION...GUSTY SOUTHERLY WILL PREVAIL AT KSLC THROUGH THE
DAY...WITH A 20 PERCENT CHANCE OF A SWITCH TO THE NORTHWEST DURING
THE 22-01Z TIMEFRAME. THERE IS ALSO A 10 PERCENT CHANCE FOR A
STRAY SHOWER OR THUNDERSTORM WITH GUSTY ERRATIC WINDS DURING THE
22-04Z TIMEFRAME.

&&

.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 LOCALLY WINDY
CONDITIONS ACROSS THE WESTERN HALF OF THE AREA...AND MAY RESULT IN
CRITICAL FIRE WEATHER CONDITIONS SHOULD FUELS BECOME SUFFICIENTLY
DRY. ADDITIONALLY...MOISTURE WITHIN THIS FLOW IS EXPECTED TO
INCREASE ACROSS THE EASTERN HALF OF UTAH THURSDAY INTO FRIDAY
BRINGING A RETURN OF SHOWERS AND THUNDERSTORMS. THIS UPSTREAM
TROUGH IS FORECAST TO SWING THROUGH THE REGION SATURDAY BRINGING A
CHANCE FOR PRECIPITATION TO NORTHERN UTAH. A MUCH COOLER AIRMASS
WILL FOLLOW FOR SUNDAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...NONE.
WY...&&

$$

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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