798
FXUS65 KSLC 182306
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
406 PM MST THU DEC 18 2025
KEY MESSAGES
- STRONG WINDS ARE EXPECTED ACROSS UINTA COUNTY, WY AND THE NORTH
SLOPE OF THE UINTA MOUNTAINS ON FRIDAY AHEAD OF OUR NEXT STORM.
- A WARM STORM SYSTEM WILL BRING VALLEY RAIN AND HIGH ELEVATION
MOUNTAIN SNOW TO NORTHERN UTAH AND SOUTHWEST WYOMING LATE FRIDAY
INTO SATURDAY.
- AFTER A RELATIVE LULL IN ACTIVE WEATHER EARLY NEXT WEEK, ANOTHER
PACIFIC STORM WILL BRING ANOTHER ROUND OF VALLEY RAIN AND
MOUNTAIN SNOW CHRISTMAS EVE AND CHRISTMAS DAY.
SHORT TERM (THROUGH 00Z MONDAY/5PM SUNDAY)
MEAGER MID-LEVEL MOISTURE
ADVECTION FROM A SHORTWAVE SKIRTING BY TO THE NORTH HAS ALLOWED
FOR LIGHT PRECIPITATION TO DEVELOP THIS AFTERNOON ACROSS FAR
NORTHERN UTAH AND SOUTHWEST WYOMING. THIS SWATH OF RAIN AND HIGH
ELEVATION SNOW IS EXPECTED TO TAPER OFF BY THE EARLY EVENING.
LITTLE IMPACTS ARE ANTICIPATED GIVEN DRY LOWER- LEVEL CONDITIONS,
WHICH WILL LIMIT ANY ACCUMULATIONS EVEN ALONG THE HIGH TERRAIN.
CONDITIONS REMAIN DRY THROUGH THE FIRST HALF OF FRIDAY, BUT WILL
BE INTERRUPTED THROUGH THE LATTER HALF OF THE DAY AS ANOTHER
LANDFALLING ATMOSPHERIC RIVER IMPACTS NORTHERN UTAH AND SOUTHWEST
WYOMING INTO SATURDAY. PRECIPITATION MAY BEGIN AS EARLY AS MID-
MORNING ON FRIDAY, MAINLY ACROSS THE HIGHER TERRAIN OF NORTHERN
UTAH AS THE REMNANTS OF A DECAYING ATMOSPHERIC RIVER SAGS INTO THE
REGION. THE MAIN PERIOD OF INTEREST FOR PRECIPITATION WILL ARRIVE
LATE FRIDAY INTO SATURDAY MORNING AS A STRENGTHENING UPPER-LEVEL
JET MOVES INLAND AND PENETRATES INTO NORTHERN UTAH THROUGH THIS
PERIOD. RAIN AND HIGH ELEVATION SNOW SHOWERS WILL INVIGORATE AND
BECOME MORE WIDESPREAD DURING THIS PERIOD BEFORE TAPERING OFF
MID-TO-LATE SATURDAY MORNING AS THE JET LIFTS NORTHWARD. SNOW
LEVELS WILL FLUCTUATE AROUND 7500-8000 FEET THROUGH MOST OF THE
EVENT, BUT A COLD FRONT TRACKING INTO FAR NORTHERN UTAH AND
SOUTHWEST WYOMING WILL BRING SNOW LEVELS DOWN TO AS LOW AS AROUND
4000-5000 FEET MAINLY NORTH OF THE I-84 TO I-80 CORRIDOR, AND
6000-7000 FEET SOUTH OF THIS CORRIDOR. AS SUCH, COULD SEE SOME
LIGHT SNOW FALLING EARLY SATURDAY ACROSS AREAS SUCH AS THE CACHE
VALLEY AND PORTIONS OF THE WASATCH BACK.
AT THIS TIME, CURRENT FORECAST SNOW ACCUMULATIONS ACROSS THE
NORTHERN MOUNTAINS REMAINS JUST BELOW CRITERIA FOR ANY WINTER
HEADLINES, AND GIVEN THE TIMING AND WARM ANTECEDENT CONDITIONS
HAVE OPTED TO HOLD OFF. HOWEVER, THERE IS LOW-END POTENTIAL FOR
OVERPERFORMANCE IN BOTH SWE AND SNOWFALL TOTALS ACROSS THE
NORTHERN MOUNTAINS. EARLY SATURDAY MORNING WILL BE THE KEY TIME TO
WATCH FOR THE POTENTIAL FOR OVERPERFORMANCE -- WHILE CHANCES ARE
LOW, AS ONLY AROUND 10% OF HIGH RESOLUTION ENSEMBLE MEMBERS
SUPPORT THIS SCENARIO, IT IS MUCH HIGHER IMPACT THAN CURRENT
FORECAST SUGGESTS. THIS SCENARIO WOULD BE DRIVEN BY STRONGER
CONVECTIVE ACTIVITY DURING THIS PERIOD RESULTING FROM STRONGER,
WEST- NORTHWESTERLY FLOW ALOFT BEING RESOLVED UNDER THE LEFT- EXIT
REGION OF THE JET MAX. FOR AN IDEA OF JUST HOW MUCH THIS STORM
COULD OVERPERFORM, THE 90TH PERCENTILE SNOWFALL TOTALS THROUGH
SATURDAY MORNING SHOW UPWARDS OF 22 INCHES ACROSS THE BEAR RIVER
RANGE AND UINTA MOUNTAINS AND 16 INCHES FOR THE CENTRAL WASATCH.
AHEAD OF THIS SYSTEM, WE WILL SEE STRONG AND POTENTIALLY DAMAGING
WINDS DEVELOPING ACROSS UINTA COUNTY, WY EARLY FRIDAY AS 700 MB
FLOW PEAKS AROUND 50-60 KTS ACROSS THE AREA. CURRENT GUIDANCE
HOLDS A 30-40% CHANCE TO REALIZE WINDS IN EXCESS OF 58 MPH. GUSTY
WINDS ARE EXPECTED TO DEVELOP ACROSS NORTHERN UTAH ON FRIDAY
AFTERNOON AS THESE WINDS MIX DOWN, WITH WIDESPREAD GUSTS 30-40
MPH.
ANOTHER, WEAKER AND WARMER WAVE OF PACIFIC MOISTURE IS EXPECTED TO
SKIRT NORTHERN UTAH LATE SUNDAY, RESULTING IN ANOTHER ROUND OF
RAIN AND HIGH ELEVATION SNOW, BUT FAVORING AREAS MAINLY NORTH OF
I-80. GIVEN THE WARMTH AND TRACK OF THIS STORM, IMPACT WILL BE
LIMITED TO THE BEAR RIVER RANGE ABOVE 8000-8500 FEET.
LONG TERM (AFTER 00Z MONDAY/5PM SUNDAY)
A NEAR-ZONAL FLOW ALOFT
WILL REMAIN IN PLACE TO BEGIN THE LONG TERM FORECAST PERIOD. A
DECAYING ATMOSPHERIC RIVER OVER NORTHERN UTAH WILL CONTINUE TO BRING
VALLEY RAIN AND MOUNTAIN SNOW MAINLY TO NORTHERN UTAH INTO MONDAY
AFTERNOON, WHILE WESTERN AND PORTIONS OF SOUTHERN UTAH CAN BE
EXPECTED TO SEE BREEZY SOUTH WINDS. THEN, AS THE FLOW TURNS MORE
SOUTHWESTERLY IN RESPONSE TO A DEEPENING TROUGH OVER THE EASTERN
PACIFIC AND MOISTURE DECREASES AND LIFTS NORTH, PRECIPITATION IS
EXPECTED TO GRADUALLY WIND DOWN LATE MONDAY. TUESDAY SHOULD BE
GENERALLY DRY, ALTHOUGH SOUTH WINDS WILL INCREASE, ESPECIALLY IN THE
WESTERN VALLEYS.
ON WEDNESDAY, A WEAKENING SHORTWAVE EMBEDDED WITHIN THE MEAN
LONGWAVE TROUGH UPSTREAM IS PROGGED TO EJECT ACROSS UTAH. THIS WILL
BE ACCOMPANIED BY A FURTHER INCREASE IN WINDS ALONG WITH INCREASED
MOISTURE FROM AN ATMOSPHERIC RIVER THAT IS EXPECTED TO SPREAD INTO
UTAH FROM THE SOUTH-SOUTHWEST. WHILE SOME TIMING DIFFERENCES EXIST
IN THE MODELS, A PERIOD OF WIDESPREAD PRECIPITATION WILL BE POSSIBLE
WITHIN THE WEDNESDAY AFTERNOON THROUGH THURSDAY TIMEFRAME. CLUSTER
ANALYSIS OF GLOBAL ENSEMBLES SHOW A SLIGHT PREFERENCE FOR THE WETTER
TWO CLUSTERS (COMPRISING 57% OF MEMBERS) OVER THE DRIER TWO ON
WEDNESDAY, WITH A MORE EVEN SPLIT FOR THURSDAY. WHILE PRECIPITATION
AMOUNTS COULD BE SIGNIFICANT WITH AN ATMOSPHERIC RIVER EVENT, MODEL
QPF SPREAD REMAINS SIGNIFICANT AT THIS TIME, AND THE ECMWF EXTREME
FORECAST INDEX IS CURRENTLY NOT INDICATING ANY NOTABLE ANOMALIES
FROM CLIMATOLOGY.
THE MILD AIRMASS ASSOCIATED WITH THE ATMOSPHERIC RIVER WILL MAINTAIN
HIGH SNOW LEVELS, WITH VALLEY RAIN AND FAIRLY DENSE MOUNTAIN SNOW
EXPECTED. SO, NOT A WHITE CHRISTMAS IN THE VALLEYS, JUST PERHAPS A
WET CHRISTMAS. GIVEN THE MILD AIRMASS, TEMPERATURES THROUGHOUT THE
LONG TERM FORECAST PERIOD WILL SEE AFTERNOON MAXES 15-25 DEGREES
ABOVE NORMAL MONDAY AND TUESDAY, COOLING SLIGHTLY TO 10-20 DEGREES
ABOVE NORMAL FOR WEDNESDAY AND THURSDAY.
AVIATION...KSLC
SOUTHERLY WINDS ARE EXPECTED TO REMAIN IN
PLACE THROUGH THE REST OF THE DAY AND INCREASE IN SPEED OVERNIGHT.
OTHERWISE, VFR CONDITIONS ARE EXPECTED TO PREVAIL, WITH A LESS THAN
20% CHANCE FOR LIGHT RAIN SHOWERS THROUGH 02Z.
REST OF UTAH AND SOUTHWEST WYOMING...LOCALIZED MVFR CONDITIONS AND
MOUNTAIN TOP OBSCURATIONS WILL BE POSSIBLE IN LIGHT RAIN AND SNOW
SHOWERS ACROSS NORTHERN UTAH AND SOUTHWEST WYOMING THROUGH AROUND
02Z, OTHERWISE VFR CONDITIONS WILL PREVAIL THROUGH THE REST OF THE
DAY AND OVERNIGHT. SOUTHERN UTAH WILL REMAIN DRY WITH SCATTERED HIGH
CLOUDS.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
SHORT TERM...WHITLAM
LONG TERM/AVIATION...CHENG
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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