448
FXUS65 KSLC 091921
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
121 PM MDT WED SEP 9 2026
KEY MESSAGES
- THERE IS A ~50% CHANCE THE WESTERN VALLEYS WILL SEE WIND GUSTS
IN EXCESS OF 45 MPH FOR 3 OR MORE HOURS SATURDAY AFTERNOON INTO
SATURDAY NIGHT AHEAD OF A STRONG COLD FRONT.
- ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE FRIDAY AND
SATURDAY AHEAD OF A COLD FRONT.
DISCUSSION
VISIBLE SATELLITE OVER THE GREAT BASIN SHOWS MOSTLY
CLEAR SKIES AREAWIDE ASIDE FROM A FEW HIGH CLOUDS ACROSS THE
UINTAS. THIS IS DUE TO OUR SYNOPTIC SETUP OF A RIDGE TO OUR SOUTH
AND AN ACTIVE NORTHERN STREAM THAT IS KEEPING US IN AN AREA OF
ZONAL FLOW RESULTING IN WARM DRY DAYS AND COOL NIGHTS WITH LIGHT
AND DIURNALLY DRIVEN WINDS. THE ONE EXCEPTION TO THIS IS ACROSS
THE WESTERN UINTA BASIN AND PORTIONS OF THE SWELL THAT TEND TO GET
ENHANCED WINDS IN WESTERLY FLOW. THIS PATTERN WILL CONTINUE ON
THURSDAY BEFORE OUR PATTERN BEGINS TO TRANSITION AHEAD OF A COLD
FRONT.
BY FRIDAY A TROUGH WILL START DIGGING INTO THE PNW WITH WESTERLY
FLOW ALOFT TRANSITIONING TO SOUTHWESTERLY FLOW. THIS WILL ALLOW
SOME MID AND UPPER LEVEL MOISTURE TO STREAM BACK INTO THE GREAT
BASIN. AS UPPER LEVEL DIFFLUENCE STARTS TO OVERSPREAD THE REGION
THERE WILL BE SOME ISOLATED SHOWERS AND THUNDERSTORMS FRIDAY AND
SATURDAY, PRIMARILY ACROSS EASTERN PORTIONS OF THE CWA, HOWEVER
SOME CAMS ARE SUGGESTING SOME CONVECTION DEVELOPING ACROSS
NORTHERN UTAH ON FRIDAY AFTERNOON AS A SUBTLE SHORTWAVE PRECEDES
THE PARENT TROUGH.
SATURDAY WILL HAVE THE STRONGEST WINDS AS SOUTHWESTERLY WINDS
ENHANCE. ENSEMBLE GUIDANCE GIVES ~50% CHANCE OF ADVISORY LEVELS
WINDS ACROSS AREAS ALONG AND WEST OF THE I-15 CORRIDOR. THESE
WINDS WILL DECREASE AFTER THE COLD FRONT MOVES THROUGH SATURDAY
NIGHT WITH SOME ENHANCED POST FRONTAL WINDS ACROSS VALLEYS OF
EASTERN UTAH. TEMPERATURES WILL FALL 10-20 DEGREES BEHIND THE
FRONT WITH OUR COLDEST AIR OF THE SEASON LIKELY BY MONDAY MORNING
WITH MANY VALLEY LOCATIONS DIPPING DOWN INTO THE 30S AND 40S.
DETERMINISTIC EC AND GFS BOTH DEPICT A REX BLOCK SETTING UP OFF
THE WEST COAST NEXT WEEK THAT WOULD LIKELY KEEP SOUTHWESTERLY
WINDS IN PLACE ALONG WITH WARM AND DRY CONDITIONS.
AVIATION
KSLC... VFR CONDITIONS WILL CONTINUE AT THE KSLC TERMINAL THROUGHOUT
THE ENTIRE FORECAST PERIOD. LIGHT WEST TO NORTHWESTERLY WINDS WILL
PERSIST THIS AFTERNOON INTO THE EVENING BEFORE SWITCHING INTO A
MORE SOUTHEASTERLY FLOW AROUND 4Z. BETWEEN 18 AND 20Z TOMORROW,
WINDS WILL SWITCH BACK TO A MORE NORTHWESTERLY REGIME FLOW.
REST OF UTAH AND SOUTHWEST WYOMING...VFR CONDITIONS WILL PERSIST
ACROSS ALL REGIONAL TERMINALS DURING THE FORECAST PERIOD. LIGHT AND
VARIABLE DIURNALLY DRIVEN WINDS ARE FORECAST ACROSS ALL TAFS
SITES. THE ONLY EXCEPTION WILL BE KEVW, WHERE WINDS GUSTS UP TO 22
KNOTS WILL BE POSSIBLE STARTING AT 19Z THIS AFTERNOON BEFORE
DIVING DOWN DURING THE LATE EVENING HOURS AROUND 4Z.
FIRE WEATHER
DRY AND WARM CONDITIONS WILL PERSIST THROUGH MUCH OF THE
WEEK DUE TO WESTERLY WINDS ALOFT. THIS WILL KEEP MINIMUM RELATIVE
HUMIDITY IN THE TEENS AND UPPER SINGLE DIGITS FOR MUCH OF THE
AREA THROUGH MUCH OF THE WEEK, WITH POCKETS OF NEAR-CRTITICAL FIRE
WEATHER CONDITIONS ACROSS PORTIONS OF THE UINTA BASIN AND SWELL
THROUGH THURSDAY. MOISTURE STARTS TO INCREASE ACROSS CENTRAL AND
SOUTHERN UTAH ON FRIDAY AND SATURDAY, ALONG WITH THE POTENTIAL FOR
SOME SHOWER AND THUNDERSTORM ACTIVITY. THERE IS LINGERING
UNCERTAINTY REGARDING THE TIMING AND EXTENT OF THIS POTENTIAL
ACTIVITY. CONFIDENCE CONTINUES TO INCREASE IN THE PRESENCE OF A
STRONG COLD FRONT THAT WILL INCREASE SOUTHWESTERLY WINDS ON
SATURDAY WITH GUSTS 30-45 MPH EXPECTED, PARTICULARLY ACROSS
WESTERN PORTIONS OF UTAH. THIS WILL RESULT IN LOCALLY CRITICAL
FIRE WEATHER CONDITIONS AS MIN RH WILL REMAIN IN THE TEENS ACROSS
LOCATIONS NEAR THE NEVADA BORDER. THIS COLD FRONT WILL MOVE
THROUGH LATE SATURDAY/EARLY SUNDAY WITH WINDS WEAKENING BEHIND THE
FRONT SUNDAY ACROSS ALL BUT EASTERN UTAH, WITH LIGHTER WINDS
STATEWIDE BY MONDAY. TEMPERATURES WILL FALL 10-20 DEGREES BETWEEN
SATURDAY AND SUNDAY FOR ALL BUT EXTREME SOUTHERN AND SOUTHEAST
UTAH.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...RED FLAG WARNING UNTIL 7 PM MDT THIS EVENING FOR WYZ277.
PUBLIC...MAHAN
AVIATION...TEKOE
FIRE WEATHER...MAHAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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