428
FXUS65 KSLC 211105
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
405 AM MST SUN DEC 21 2025
KEY MESSAGES
- WELL ABOVE NORMAL TEMPERATURES (+15-20 DEGREES) SPREAD BACK INTO
UTAH AND SOUTHWEST WYOMING THROUGH AT LEAST TUESDAY.
- A SERIES OF WEAK WEATHER DISTURBANCES WILL PASS THROUGH NORTHERN
UTAH AND SOUTHWEST WYOMING SUNDAY INTO MONDAY, BRINGING ANOTHER
ROUND OF HIGH ELEVATION SNOW (8,500FT+) AND VALLEY RAIN,
PRIMARILY FOR AREAS NEAR THE UTAH/IDAHO BORDER.
- WINDS WILL BE BREEZY AT TIMES THROUGH TUESDAY, PRIMARILY OVER
WESTERN UTAH, BEFORE BECOMING STRONGER WEDNESDAY INTO EARLY
FRIDAY WITH THE ARRIVAL OF ANOTHER WARM PACIFIC STORM SYSTEM.
- ANOTHER WARM STORM SYSTEM WILL IMPACT THE AREA EARLY NEXT WEEK,
BRINGING MOUNTAIN SNOW AND VALLEY RAIN ACROSS UTAH.
SHORT TERM (THROUGH 12Z/5AM WEDNESDAY)
ANOTHER SURGE OF
MOISTURE PUSHES INTO NORTHERN UTAH THROUGH THE MORNING HOURS,
ALLOWING FOR LIGHT PRECIPITATION TO SPREAD ACROSS AREAS PRIMARILY
NORTH OF THE I-80 CORRIDOR. WITH STRONG WARM ADVECTION OVERHEAD,
SNOW LEVELS WILL RISE THROUGHOUT THE DAY, STARTING AROUND
7,000-8,000FT AND REACHING UPWARDS OF 9,500FT ACROSS THE NORTHERN
UTAH MOUNTAINS BY THE AFTERNOON HOURS, FORCING LIGHT RAIN BELOW
THIS ELEVATION BAND.
THIS STREAM OF MOISTURE WILL BE THE PRIMARY DRIVER OF OUR WEATHER
OVER THE NEXT COUPLE OF DAYS. THERE IS GENERALLY HIGH CONFIDENCE
THAT NORTHERN UTAH WILL REMAIN ON THE SOUTHERN PERIPHERY OF THIS
MOISTURE PLUME WHICH WILL KEEP PRECIPITATION TOTALS MUTED ACROSS
THE AREA. WHILE THE NORTHERN BEAR RIVER MOUNTAINS ARE SLATED TO
ACCUMULATE THE MOST (1.5-2 INCHES SWE), MINIMAL SNOW ACCUMULATIONS
ARE EXPECTED DUE TO VERY HIGH SNOW LEVELS. AS SUCH, IMPACTS
RELATED TO ANY PRECIPITATION WILL BE MINIMAL. THE MOISTURE AXIS
WILL PUSH NORTHWARD BY TUESDAY, ALLOWING FOR A PRECIPITATION-FREE
DAY ACROSS THE AREA.
IN ADDITION TO THE MOISTURE STREAM, WE FIND OURSELVES ON THE
SOUTHEAST PERIPHERY OF A BROAD UPPER LEVEL TROUGH WHICH WILL HELP
TO ENHANCE FLOW OVERHEAD. AS SUCH, EACH DAY ACROSS THE WESTERN
HALF OF UTAH WILL EXPERIENCE BREEZY AFTERNOON WINDS. NOTHING OF
MAJOR CONCERN FOR TRAVEL, BUT GUSTS OF UPWARDS OF 25-35 MPH CAN BE
EXPECTED, PRIMARILY ACROSS WEST-CENTRAL UTAH, THROUGH AT LEAST
THE MIDDLE OF THE WEEK AS THIS UPSTREAM WEATHER FEATURE REMAINS
QUASI-STATIONARY.
AS NOTED ABOVE, PERSISTENT WARM ADVECTION WILL SPREAD WARMER
TEMPERATURES INTO THE REGION THROUGH AT LEAST MONDAY, ALLOWING FOR
A GRADUAL WARMING TREND THROUGH MONDAY AND POTENTIALLY TUESDAY.
DAYTIME HIGH TEMPERATURES ACROSS THE REGION ARE EXPECTED TO RETURN
BACK TO 15-20 DEGREES ABOVE AVERAGE. AT THIS POINT, WE'RE ON
TRACK TO BLOW THE PREVIOUS RECORD FOR AVERAGE MAX T THROUGH
DECEMBER OUT OF THE WATER. NOT THE STATISTICS YOU WANT TO BE
HEARING AS WE ARE NOW AT THE BEGINNING OF ASTRONOMICAL WINTER.
LONG TERM (AFTER 12Z/5AM WEDNESDAY)
AN UPPER TROUGH IS
FORECAST TO PARK ITSELF OFF THE WEST COAST TO KICK OFF THE
EXTENDED FORECAST. THIS TROUGH IS EXPECTED TO GRADUALLY AMPLIFY
THROUGHOUT WEDNESDAY WITH ENHANCED SOUTHWESTERLIES OVERSPREADING
THE INTERMOUNTAIN WEST WITHIN A DIFFLUENT FLOW REGIME. THIS WILL
RESULT IN AN ATMOSPHERIC RIVER TRANSPORTING AMPLE MOISTURE TO THE
REGION RESULTING IN PERSISTENT AND WIDESPREAD PRECIPITATION ACROSS
THE FORECAST AREA WEDNESDAY THROUGH AT LEAST FRIDAY.
ON WEDNESDAY, WINDS INCREASE IN MAGNITUDE ACROSS THE REGION AS A
DEEPENING SHORTWAVE EMBEDDED WITHIN THE ALREADY ENHANCED MEAN FLOW
TRAVERSES ACROSS NORTHERN UT THROUGHOUT THE DAY. THIS SHORTWAVE IS
EXPECTED TO OVERLAP WITH THE ARRIVAL OF MOISTURE WITHIN THE
ATMOSPHERIC RIVER KICKING OFF A PROLONGED PERIOD OF PRECIPITATION
ACROSS THE ENTIRE FORECAST AREA. SNOW LEVELS ARE EXPECTED TO REMAIN
HIGH DUE TO THE WARM NATURE OF ATMOSPHERIC RIVERS, KEEPING MOST
VALLEY LOCATIONS SOCKED IN WITH RAIN. THIS GENERAL PATTERN IS
EXPECTED TO PERSIST THROUGH AT LEAST THURSDAY AS THE UPPER TROUGH
REMAINS PARKED OFF THE PACIFIC COAST.
COMPARED TO LAST NIGHTS FORECAST, ENSEMBLE GUIDANCE APPEARS TO HAVE
A BETTER HANDLE ON FRIDAY, KEEPING THE TROUGH PARKED OFF THE WEST
COAST INTO THE AFTERNOON BEFORE IT BEGINS EJECTING INLAND.
AFTER IT BEGINS EJECTING AND INTO SATURDAY, HOWEVER, ENSEMBLES BEGIN
TO DIVERGE REGARDING TIMING AND ESPECIALLY THE GENERAL UPPER AIR
PATTERN THAT WE CAN EXPECT. THE CURRENT 00Z SUITE OF OPERATIONAL
LONG-RANGE GUIDANCE INDICATES A SPLIT FLOW REGIME WITH AN UPPER
TROUGH GRAZING NORTHERN UT AND A CUTOFF LOW EJECTING EAST INTO
SOUTHERN CA. DIVING INTO ENSEMBLE GUIDANCE, HOWEVER, REFLECTS THE
UNCERTAINTY REGARDING THIS DESPITE GUIDANCE GRADUALLY TRENDING
TOWARD THIS SOLUTION OVER THE PAST FEW DAYS. AS OF NOW, IT STILL
REMAINS A NEARLY 50/50 SPLIT AMONGST ALL GLOBAL MEMBERS WITH 50%
SUPPORTING HIGHER GEOPOTENTIAL HEIGHTS ACROSS SOUTHWEST CANADA,
YIELDING A SOUTHERN TRACK SUPPORTING THE POSSIBLE DEVELOPMENT OF A
CUTOFF LOW. THE OTHER 50% SUPPORTS SLIGHTLY LOWER GEOPOTENTIAL
HEIGHTS TO OUR NORTH, ALLOWING THE UPPER TROUGH TO PROGRESS EAST AND
NOT CUT OFF TO OUR SOUTH. TIMING IS QUITE DIFFICULT TO IRON DOWN AS
EACH SOLUTION REMAINS QUITE UNCERTAIN WITHIN CLUSTER ANALYSIS,
THOUGH WHAT WE CAN ASSUME IS THAT AN OPEN WAVE WOULD YIELD A MORE
WIDESPREAD PRECIPITATION EVENT FOR THE ENTIRE FORECAST AREA WHILE A
SOUTHERN CUTOFF LOW WOULD GENERALLY FAVOR MORE PRECIPITATION ACROSS
THE SOUTHERN HALF OF THE STATE.
FINALLY, TEMPERATURES WILL RUN QUITE WARM THROUGH THE MAJORITY OF
THE EXTENDED FORECAST PERIOD WITH TEMPERATURES 15-20F ABOVE AVERAGE
EXPECTED THROUGH THURSDAY. WE ARE EXPECTED TO COOL OFF BRIEFLY ON
FRIDAY AS "COLDER" AIR PUSHES IN ON FRIDAY, THOUGH WE WILL REMAIN
AROUND 10F ABOVE AVERAGE FOR MOST LOCATIONS. WITH NO VALLEY SNOW IN
THE FORECAST, WE WILL CONTINUE NUDGING EVEN CLOSER TO THE LATEST
MEASURABLE SNOWFALL AT SLC, WITH THAT DATE BEING JANUARY 2ND.
ANYTHING PAST THAT WILL SET THE NEW RECORD FOR LATEST MEASURABLE
SNOWFALL FOR SLC SINCE RECORDS BEGAN.
AVIATION...KSLC
PERIODS OF VARIABLE WINDS WINDS MAY OCCUR OVER
THE NEXT TWO HOURS BEFORE CLOCKING TO SOUTHEASTERLY, PERSISTING
THROUGH THE REMAINDER OF THE TAF PERIOD. GUSTS IN EXCESS OF 20KTS
DEVELOP AROUND 15Z, ALSO PERSISTING THROUGH THE MAJORITY OF THE TAF
PERIOD. OCCASIONAL RAIN SHOWERS ARE EXPECTED THIS AFTERNOON WITH
MOUNTAIN OBSCURATIONS POSSIBLE AS LOWER CEILINGS BUILD IN FOLLOWING
15Z.
REST OF UTAH AND SOUTHWEST WYOMING
ENHANCED SOUTH SOUTHWEST FLOW
WILL DEVELOP ACROSS THE AIRSPACE, EXCEPT FOR KSGU DUE TO SHELTERING.
GUSTS WILL INCREASE THROUGHOUT THE MORNING HOURS WITH THE MAJORITY
OF OUR SITES SEEING GUSTS IN EXCESS OF 20KTS. THERE IS A CHANCE THAT
KEVW SEES WIND GUSTS IN EXCESS OF 40KTS FOLLOWING 18Z FOR A COUPLE
HOURS. ACROSS NORTHERN UT AND SOUTHWEST WY, SCATTERED SHOWERS ARE
POSSIBLE INTO THE MID AFTERNOON WITH CEILINGS PERHAPS LEADING TO
MOUNTAIN OBSCURATIONS. WINDS ARE EXPECTED TO REMAIN ELEVATED
THROUGHOUT THE TAF PERIOD, THOUGH CEILINGS ARE EXPECTED TO IMPROVE
NEAR THE END OF THE TAF PERIOD.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
SHORT TERM...WEBBER
LONG TERM...WORSTER
AVIATION...WORSTER
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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