892
FXUS65 KSLC 211020
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
420 AM MDT TUE OCT 21 2025
SYNOPSIS
PLEASANT WEATHER WILL BE IN STORE ACROSS UTAH AND
SOUTHWEST WYOMING TODAY AS HIGH PRESSURE BRINGS CLEAR SKIES AND
WARMING TEMPERATURES. AN UPPER-LEVEL LOW SHIFTS INTO THE REGION
WEDNESDAY EVENING THROUGH THURSDAY, BRINGING SCATTERED SHOWERS AND
ISOLATED THUNDERSTORMS ACROSS SOUTHERN AND CENTRAL UTAH. BRIEF
HIGH PRESSURE BUILDS INTO THE REGION IN THE WAKE OF THE LOW BEFORE
AN EARLY SEASON WINTER STORM MOVES INTO UTAH BY THE WEEKEND.
SHORT TERM (THROUGH 12Z/6AM FRIDAY)
COLD MORNING TEMPERATURES
ARE EMERGING ACROSS THE REGION TODAY IN THE WAKE OF THE PREVIOUS
COLD FRONT THAT MOVED THROUGH UTAH AND SOUTHWEST WYOMING. ALREADY
(AT 330AM), TEMPERATURES ALONG THE WASATCH FRONT RANGE FROM THE
LOW-TO-MID 30S, WITH SEVERAL AREAS WITHIN, AND OUTSIDE OF, THE
CURRENT FREEZE WARNINGS ALREADY REACHING FREEZING. TODAY,
TEMPERATURES WILL WARM ACROSS THE ENTIRETY OF THE AREA AS WEAK
WARM ADVECTION SPREADS INTO THE EASTERN GREAT BASIN AS A RIDGE
BEGINS TO BUILD. WHILE TRANSIENT IN NATURE, THIS RIDGE WILL BRING
QUIET WEATHER CONDITIONS ACROSS UTAH AND SOUTHWEST WYOMING FOR
TUESDAY AND THE FIRST HALF OF WEDNESDAY.
BY WEDNESDAY EVENING, AN OFFSHORE LOW, WHICH HAS BEEN LINGERING
FOR SEVERAL DAYS NOW, WILL BEGIN TO PUSH INLAND AND HELP TO SPREAD
MOISTURE ACROSS THE CENTRAL AND SOUTHERN PORTIONS OF UTAH. BY
EARLY WEDNESDAY EVENING, SUFFICIENT MOISTURE AND LIFT WILL HELP TO
BEGIN KICKING OFF ISOLATED RAIN SHOWERS IN SOUTHWEST UTAH. THIS
LOW WILL PROGRESS FURTHER INTO THE FORECAST ARE THROUGH THE
OVERNIGHT HOURS INTO THURSDAY, ALLOWING PRECIPITATION TO BECOME
MUCH MORE WIDESPREAD ACROSS THE SOUTHERN AREA. AS THE UPPER-LEVEL
LOW BEGINS TO TRANSLATE OVER SOUTHERN UTAH WEDNESDAY NIGHT,
INCREASED INSTABILITY MAY LEAD TO A FEW ISOLATED THUNDERSTORMS TO
DEVELOP. WITH COLUMN PRECIPITABLE WATER REACHING UPWARDS OF
150-200% OF NORMAL FOR THIS TIME OF YEAR, THESE THUNDERSTORMS WILL
BE CAPABLE OF PRODUCING MODERATE TO HEAVY RAINFALL. AS SUCH, FLASH
FLOOD WILL BE POSSIBLE FOR NORMALLY PRONE AREAS FROM WEDNESDAY
EVENING THROUGH THURSDAY AFTERNOON.
BY THURSDAY EVENING THE CENTER OF THE LOW WILL PUSH INTO SOUTHWEST
COLORADO WITH A RIDGE OF HIGH PRESSURE BUILD IN FROM THE WEST,
HELPING TO STABILIZE CONDITIONS THROUGH THE REMAINDER OF THE
EVENING.
LONG TERM (AFTER 12Z/6AM FRIDAY)
RIDGING BEGINS TO BUILD BACK INTO
THE AREA ON FRIDAY AS SOUTHERLY FLOW RETURNS WITH WARM AIR
ADVECTION. THIS WILL PERSIST THROUGH SATURDAY BEFORE A DECAYING
ATMOSPHERIC RIVER ACCOMPANIES A TROUGH MOVING INTO NORTHERN UTAH
FROM THE PNW. THIS WILL BRING WIDESPREAD VALLEY RAIN AND MOUNTAIN
SNOW WITH SNOW LEVELS DROPPING CLOSE TO VALLEY FLOORS BY MONDAY
MORNING AS NORTHWEST FLOW COINCIDES WITH MINIMUM H7 TEMPERATURES. A
RIDGE QUICKLY BUILDS INTO THE AREA BY TUESDAY.
WARM SOUTHERLY FLOW ON FRIDAY AND SATURDAY WILL RESULT IN
TEMPERATURES A FEW DEGREES ABOVE NORMAL. SOUTHERLY FLOW WILL
INCREASE AHEAD OF AN APPROACHING TROUGH FROM THE PNW. GUSTS ACROSS
PORTIONS OF SOUTHWEST UTAH AND SW WYOMING WILL APPROACH 30 MPH
DURING THE DAY ON SATURDAY.
A NEGATIVELY TILTED TROUGH MOVING INTO THE PACIFIC NORTHWEST WILL BE
ACCOMPANIED BY A SUBSTANTIAL ATMOSPHERIC RIVER. THIS TROUGH WILL
BRING MOISTURE FROM THE DECAYING ATMOSPHERIC RIVER INTO NORTHERN
UTAH ALONG A STRONG COLD FRONT LATE SATURDAY NIGHT AND INTO SUNDAY.
CURRENT GUIDANCE SHOWS TWO WAVES OF PRECIPITATION. THIS FIRST IS THE
ONE THAT WAS MENTIONED LATE SATURDAY INTO SUNDAY. THIS WILL BE IN
THE FORM OF VALLEY RAIN AND MOUNTAIN SNOW WITH SNOW LEVELS STARTING
~8500 FEET AND FALLING TO ~7000 FEET DURING THE DAY ON SUNDAY. THE
SECOND ROUND OF PRECIPITATION WILL COME WITH A TRAILING SHORTWAVE
THAT WILL BE ASSOCIATED WITH THE COLDEST AIR ALOFT. 700 MB
TEMPERATURES WILL LIKELY BOTTOM OUT BETWEEN -5 AND -11C (25TH TO
75TH PERCENTILES) BY MONDAY MORNING. MOISTURE IN THE MID LEVELS WILL
REMAIN IN PLACE. GIVEN STRONG WEST TO NORTHWEST FLOW AND WARM GSL
TEMPERATURES EXPECT LAKE ENHANCED SNOW TO DEVELOP SOUTH AND EAST OF
THE GSL. GIVEN THE STRONG LAPSE RATES, ANY BANDS THAT DEVELOP WILL
BE CAPABLE OF DRAGGING SNOW LEVELS CLOSE TO VALLEY FLOORS,
PARTICULARLY UNDER THE HEAVIEST BANDS.
EXACT TOTALS FOR RAIN AND SNOW STILL VARY WIDELY GIVEN VARIATIONS IN
THE EXACT TRACK OF THE STORM AND UNCERTAINTY WITH REGARD TO THE WIND
DIRECTION ALOFT DURING THE TRAILING WAVE. HOWEVER, THERE WILL BE A
STRONG GRADIENT IN QPF TOTALS FROM NORTH TO SOUTH. REGARDLESS, THE
COLDEST AIR OF THE SEASON WILL LIKELY ACCOMPANY THIS STORM WITH MANY
LOCATIONS EXPERIENCING FREEZING CONDITIONS BY TUESDAY MORNING.
AVIATION...KSLC
VFR CONDITIONS WILL PERSIST FOR THE KSLC TERMINAL
THROUGH THE PERIOD. DRY CONDITIONS AND CLEAR SKIES WILL CONTINUE
WITH LIGHT SOUTHERLY FLOW TRANSITIONING TO LIGHT NORTHERLY FLOW
DURING THE AFTERNOON.
REST OF UTAH AND SOUTHWEST WYOMING
VFR CONDITIONS WILL PERSIST
FOR THE ENTIRE AIRSPACE THROUGH THE PERIOD. DRY CONDITIONS AND
MOSTLY CLEAR SKIES WILL CONTINUE WITH LIGHT AND DIURNALLY DRIVEN
WINDS.
SLC WATCHES/WARNINGS/ADVISORIES
UT...FREEZE WARNING UNTIL 9 AM MDT THIS MORNING FOR UTZ103-104.
WY...NONE.
SHORT TERM...WEBBER
LONG TERM/AVIATION...MAHAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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