Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 050341
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
941 PM MDT FRI SEP 4 2015

.SYNOPSIS...AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL MOVE ACROSS
THE NORTHERN ROCKIES AND GREAT BASIN THROUGH SATURDAY...WITH AN
ASSOCIATED COLD FRONT DROPPING THROUGH SOUTHWEST WYOMING AND
UTAH. A GENERAL DRYING AND WARMING TREND IS EXPECTED NEXT WEEK AS
A RIDGE OF HIGH PRESSURE BUILDS OVER THE REGION.

&&

.DISCUSSION...A MID LEVEL TROUGH ENCOMPASSES MUCH OF THE WESTERN
CONUS THIS EVENING...ANCHORED AROUND AN UPPER LOW SPINNING OVER
THE INTERIOR PACIFIC NORTHWEST. THE LOW LEVEL BAROCLINIC ZONE
ASSOCIATED WITH THIS TROUGH CURRENTLY STRETCHES ACROSS CENTRAL ID
INTO NORTHEAST NV...AND WILL GRADUALLY ENCROACH INTO NORTHWEST UT
OVERNIGHT WITH THE PRE-FRONTAL TROUGH LIKELY STALLING ACROSS THE
GSL DURING THE OVERNIGHT HOURS. AHEAD OF THIS FEATURE GUSTY
SOUTHERLY WINDS CONTINUE...AND ALTHOUGH SPEEDS WILL TAPER THROUGH
THE REMAINDER OF THE EVENING HOURS WITH THE LOSS OF BOUNDARY
LAYER MIXING...STILL LIKELY MAINTAIN GUSTS IN THE 25-35 MPH RANGE
AT TIMES. OTHERWISE THE 00Z KSLC SHOWED MODEST INSTABILITY OVERTOP
A DEEPLY MIXED BOUNDARY LAYER...AND WITH WEAK LARGE SCALE ASCENT
AHEAD OF THE APPROACHING FRONTAL BAND...MAY WELL CONTINUE TO SEE
ISOLATED CONVECTION FIRE INTO THE OVERNIGHT HOURS.

THE PARENT TROUGH IS FORECAST TO LIFT THROUGH THE NORTHERN ROCKIES
BRUSHING NORTHERN UT DURING THE DAY SATURDAY...WHILE PUSHING THE
FRONTAL BOUNDARY THROUGH THE CENTRAL/SOUTHERN WASATCH FRONT MIDDAY
AND EVENTUALLY INTO CENTRAL UT. GUSTY PRE-FRONTAL SOUTHERLY WINDS
WILL ONCE AGAIN DEVELOP BY LATE MORNING...ALTHOUGH WITH THE SYSTEM
LIFTING NORTH OF THE AREA A WEAKENING GRADIENT AND DECREASING FLOW
ALOFT WILL REDUCE GUST POTENTIAL THROUGH THE DAY. INSTABILITY
SHOULD BE SUFFICIENT TO SUPPORT AT LEAST ISOLATED CONVECTION
ALONG AND AHEAD OF THE FRONT DURING THE AFTERNOON AND EVENING.

&&

.AVIATION...GUSTY SOUTHERLY WINDS WILL CONTINUE AT THE KSLC
TERMINAL THROUGH THE OVERNIGHT HOURS...WITH A 30 PERCENT CHANCE
THAT INTERMITTENT GUSTS IN EXCESS OF 25 KTS DEVELOP. SOUTH WINDS
WILL RAMP BACK UP TOMORROW MORNING AHEAD OF A STRONG COLD FRONT
EXPECTED TO MOVE THROUGH THE TERMINAL BETWEEN 19-20Z. BRIEF
PERIODS OF BLOWING DUST ARE POSSIBLE...MOST LIKELY BETWEEN 17-20Z
TOMORROW.

&&

.FIRE WEATHER...RED FLAG WARNING CONTINUES THROUGH SATURDAY EVENING
FOR THE WESTERN VALLEYS. RH VALUES BETWEEN 10 AND 15 PERCENT...ALONG
WITH VERY STRONG WINDS WILL CONTRIBUTE TO CRITICAL FIRE WEATHER
CONDITIONS. SOUTHERLY GUSTS UP TO 50 MPH FOR THE REST OF THIS
AFTERNOON...POTENTIALLY LOCALLY STRONGER TOMORROW AFTERNOON INTO THE
EARLY EVENING. A SIGNIFICANT WIND SWITCH TO THE NORTHWEST IS
FORECAST WITH THE COLD FRONT SATURDAY AFTERNOON AND EVENING. WINDS
DIMINISH SATURDAY NIGHT. COOLER CONDITIONS CAN BE EXPECTED SUNDAY.

CONVECTION APPEARS ISOLATED MOST LOCATIONS...BUT LIGHTNING AND
ENHANCED/ERRATIC WINDS WILL BE A THREAT CONCURRENT WITH THE LARGER
SCALE WIND SYSTEM FOR THE REMAINDER OF TODAY AND TOMORROW.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...RED FLAG WARNING UNTIL 10 PM MDT SATURDAY FOR UTZ478-492-495-497.

     WIND ADVISORY UNTIL 10 PM MDT SATURDAY FOR UTZ003-005-015-016.

     WIND ADVISORY FROM 8 AM TO 10 PM MDT SATURDAY FOR UTZ001-002-004.

WY...RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR WYZ277

&&

$$

SEAMAN/ROGOWSKI

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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