Area Forecast Discussion
Issued by NWS Salt Lake City, UT

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000
FXUS65 KSLC 212120
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
320 PM MDT MON JUL 21 2014

.SYNOPSIS...A DRY SOUTHWEST FLOW WILL BE OVER THE AREA THROUGH
TUESDAY. MOISTURE WILL INCREASE FROM THE SOUTH AGAIN ON WEDNESDAY
AND COULD LINGER ACROSS MAINLY SOUTHERN AND EASTERN UTAH THROUGH
THE END OF THE WEEK.


&&

.DISCUSSION...MSAS MSLP ANALYSIS INDICATES A WEAK SURFACE TROUGH
DRAPED FROM SOUTHERN IDAHO SOUTHWEST TO ROUGHLY WENDOVER. UPSTREAM
OF THIS FEATURE ADEQUATE MOISTURE AND SUBSTANTIAL EFFECTIVE BULK
SHEAR HAS ALLOWED FOR SCATTERED STORM CELLS TO DEVELOP ACROSS THE
EXTREME NORTHWEST. ALTHOUGH THE CONVECTIVE ENVIRONMENT IS NOT AS
FAVORABLE FOR ORGANIZATION AS IT IS ACROSS FAR SOUTHERN
IDAHO...SOME OF THESE CELLS COULD BE EFFECTIVE WIND PRODUCERS
AROUND PARK VALLEY/RAFT RIVERS THROUGH THIS EVENING BEFORE
DISSIPATING.

FLOW ALOFT WILL CONTINUE TO DRY ALL AREAS TOMORROW AS HIGH
PRESSURE CONTINUES TO GRADUALLY SHIFT WEST TOWARDS THE FOUR
CORNERS. WITH GOOD MIXING DURING THE AFTERNOON HOURS...EXPECT
ANOTHER DAY OF BREEZY SOUTHERLY WINDS ACROSS THE WESTERN VALLEYS
AND SLIGHTLY WARMER TEMPS AREAWIDE. SEE FIRE WEATHER DISCUSSION
BELOW FOR IMPACTS REGARDING WINDS/LOW HUMIDITY.

CONTINUED BUT GRADUAL WESTWARD PROPAGATION OF THE HIGH WILL ALLOW
TRAJECTORIES TO BECOME MORE FAVORABLE FOR A RESURGENCE OF
SUBTROPICAL MOISTURE TUESDAY NIGHT THROUGH WEDNESDAY. THIS OWING
FOR A GREATER THREAT OF CONVECTION MOST AREAS EAST OF INTERSTATE
15 WEDNESDAY AFTERNOON...ESPECIALLY THE SOUTHEAST WHERE PWATS ARE
PROGGED TO EXCEED 1 INCH. LOCATION OF HIGH WILL AID FURTHER
WARMING MOST ALL AREAS...WITH TEMPS MAKING ANOTHER RUN AT TRIPLE
DIGITS WEDNESDAY AFTERNOON. THIS SAID...CLOUD COVER MAY BE A
LIMITING FACTOR OF REALIZING FULL H7 POTENTIAL SOME LOCALS.

LARGE SCALE PATTERN EVOLUTION WITHIN GLOBAL MODELS SUGGESTS THE
AFOREMENTIONED HIGH WILL FLATTEN AT LEAST SOME AND BULGE WEST BY
THURSDAY...THIS AS A FAIRLY SUBSTANTIAL TROUGH CARVES THROUGH THE
PACNW ON INTO THE NORTHERN ROCKIES STATES. A MORE WESTERLY
TRAJECTORY OF WINDS ALOFT SHOULD PUSH DEEPER MOISTURE EAST INTO
COLORADO COME THURSDAY...BUT LEFT MENTION OF ISOLATED CONVECTION
ACROSS THE SOUTHEAST THURSDAY AS THIS MAY NOT OCCUR UNTIL LATE
DAY.

RIDGE AXIS LATE WEEK LOOKS TO STAY SOUTH OF THE BORDER ALLOWING A
DRY WESTERLY FLOW TO PERSIST ACROSS THE AREA. CAN NOT RULE OUT
THIS AXIS SHIFTING SLIGHTLY NORTH ALLOWING FOR SOME CONVECTION
ACROSS THE FAR SOUTH FRIDAY THROUGH THE WEEKEND...BUT GLOBAL
GUIDANCE SUPPORTS DRY CONDITIONS AREAWIDE AT THIS TIME.

&&

.AVIATION...SOUTH WINDS ARE EXPECTED TO CONTINUE THROUGH THE DAY AT
THE KSLC TERMINAL. OCCASIONAL GUST OVER 30 MPH POSSIBLE THROUGH
02Z. ALSO A 10 PERCENT CHANCE EXISTS THAT WINDS WILL SWITCH TO THE
NORTHWEST DURING THE 22-01Z WINDOW. OPERATIONAL WEATHER CONCERNS ARE
EXPECTED TO BE MINIMAL WITH VFR CONDITIONS THROUGH THE VALID TAF
PERIOD.

&&

.FIRE WEATHER...THE MAIN CONCERN FOR THE FORECAST PERIOD IS THE
POTENTIAL FOR CRITICAL FIRE WEATHER CONDITIONS TO DEVELOP ACROSS
WESTERN UTAH TODAY AND TOMORROW AFTERNOON DUE TO GUSTY WINDS AND LOW
RELATIVE HUMIDITY. A RED FLAG WARNING HAS BEEN ISSUED FOR WESTERN
UTAH THROUGH TOMORROW EVENING. IT IS POSSIBLE THAT WIND SPEEDS WILL
BE JUST BELOW CRITICAL VALUES TOMORROW AFTERNOON ACROSS WESTERN
UTAH. HOWEVER...THE POTENTIAL FOR STRONGER UPPER LEVEL WINDS TO MIX
TO THE SURFACE IS OF CONCERN...AND SO UPGRADED THE WATCH TO A
WARNING FOR TOMORROW.

MOISTURE WILL INCREASE ACROSS SOUTHERN AND EASTERN UTAH
WEDNESDAY...RESULTING IN AFTERNOON SHOWERS AND THUNDERSTORMS OVER
THE HIGHER TERRAIN. ACROSS NORTHWESTERN UTAH ON WEDNESDAY THERE IS
THE POTENTIAL FOR WINDS TO REACH CRITICAL LEVELS...BUT CONFIDENCE IS
NOT HIGH ENOUGH AT THIS TIME TO WARRANT ISSUING ANY HIGHLIGHTS FOR
NORTHWESTERN UTAH ON WEDNESDAY.

HIGH PRESSURE WILL BUILD OVER THE FORECAST AREA FRIDAY INTO THE
WEEKEND...BRINGING A PERIOD WITH WARMING TEMPERATURES...DRY
CONDITIONS...AND TERRAIN DRIVEN WINDS.

&&

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

WY...NONE.
&&

$$

MERRILL/YOUNG/HOSENFELD


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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