440
FXUS65 KSLC 142229
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
329 PM MST SUN DEC 14 2025
KEY MESSAGES
- DRY AND GENERALLY MILD CONDITIONS WILL PERSIST INTO EARLY NEXT
WEEK.
- UNSETTLED CONDITIONS RETURN TO THE NORTHERN HALF OF THE AREA
TUESDAY NIGHT INTO THE WEEKEND, WITH PERIODS OF VALLEY RAIN AND
MOUNTAIN SNOW.
DISCUSSION
EARLY AFTERNOON UPPER AIR ANALYSIS INDICATES BROAD
UPPER LEVEL RIDGING ACROSS THE SOUTHWEST, WITH A SHORTWAVE TROUGH
UNDERCUTTING THE RIDGE, ACROSS WESTERN NEVADA. AN ACTIVE NORTHERN
STREAM CONTINUES, LARGELY IMPACTING THE PACIFIC NORTHWEST INTO THE
NORTHERN TIER OF THE INTERIOR WEST.
THE PREVIOUSLY MENTIONED SHORTWAVE TROUGH WILL SHIFT EAST ACROSS
UTAH THROUGH MONDAY, BRINGING INCREASED CLOUD COVER THROUGH AT
LEAST MONDAY MORNING. THIS WILL LIKELY KEEP THE NORMALLY COLDER
VALLEYS FROM RADIATING OUT AS MUCH AS THE PREVIOUS NIGHTS. THIS
MAY ALSO ALLOW INVERSIONS TO MODERATE IN THE NORTHERN VALLEYS TO
SOME DEGREE. EVEN SO, GUIDANCE SUGGESTS SOME PATCHY FOG WILL BE
POSSIBLE FOR THE CACHE AND EASTERN BOX ELDER COUNTY AREAS...BUT
TIMING OF CLOUDS WILL BE KEY. FOR NOW ONLY HAVE A 20% CHANCE OF
FOG IN THESE AREAS.
IN THE WAKE OF THIS WEAKENING SHORTWAVE TROUGH, WESTERLY TO
NORTHWESTERLY FLOW WILL BUILD INTO THE REGION MONDAY AFTERNOON
INTO TUESDAY AS A SHORTWAVE TROUGH EMBEDDED IN THE NORTHERN STREAM
FAR TO THE NORTH PASSES THROUGH MONTANA INTO NORTH DAKOTA. COLD
AIR ADVECTION IN ASSOCIATION WITH THIS FLOW WILL GRADUALLY
DECREASE 700MB TEMPERATURES, LIKELY WEAKENING INVERSIONS ACROSS
THE NORTHERN VALLEYS TUESDAY. FLOW WILL BACK BRIEFLY BEHIND THIS
SHORTWAVE TROUGH LATER TUESDAY INTO WEDNESDAY.
AS A LANDFALLING ATMOSPHERIC RIVER AND ASSOCIATED JET MAX IMPINGE
ON NORTHERN UTAH WEDNESDAY, PERIODS OF VALLEY RAIN AND MOUNTAIN
SNOW WILL DEVELOP ACROSS NORTHERN UTAH WEDNESDAY MORNING, BUILDING
SOUTH WITH TIME AS THE BEST DYNAMICS SHIFT INTO THE REGION. 25TH
TO 75TH PERCENTILE SNOW WATER EQUIVALENT IS AROUND 0.30-0.80" FOR
THE NORTHERN MOUNTAINS, EXCEPT 0.40-0.90" FOR THE BEAVER RIVER
RANGE. WITH SNOW LEVELS AROUND 8500 FEET INITIALLY, SNOW RATIOS
WILL BE ATYPICAL FOR THE WASATCH, REMAINING UNDER 8 TO 9:1 OR SO.
DEEP SYNOPTIC LIFT WILL SHIFT TO THE EAST BY EARLY THURSDAY, WITH
ANOTHER LULL IN THE ACTION THROUGH THURSDAY AFTERNOON INTO
THURSDAY EVENING. A LANDFALLING ATMOSPHERIC RIVER WITH ASSOCIATED
JET MAX WILL AGAIN IMPINGE ON THE AREA FRIDAY INTO SATURDAY...BUT
THERE IS A WIDE VARIATION IN EXACTLY HOW THIS UNFURLS THROUGH
SATURDAY. GUIDANCE HAS A BROAD RANGE OF SOLUTIONS FROM THE BEST
JET DYNAMICS REMAINING TO THE NORTH TO THE JET SHIFTING AS FAR
SOUTH AS CENTRAL UTAH. CURRENT FORECAST IS SITTING RIGHT AROUND
THE 50TH PERCENTILE, BUT GIVEN THE "WARM" NATURE OF THIS AR, AGAIN
SNOW RATIOS WILL BE MORE REFLECTIVE OF THE SIERRAS VERSUS THE
WASATCH. 25TH TO 75TH PERCENTILE SNOW WATER EQUIVALENT FOR THIS
STORM IS AROUND 0.50-1.50" ACROSS THE NORTHERN MOUNTAINS, LESS FOR
MOST VALLEYS (EXCEPT WEBER/DAVIS/EASTERN BOX ELDER COUNTY AREAS
THAT TEND TO DO WELL IN WESTERLY FLOW, ATMOSPHERIC RIVER
SCENARIOS). 25TH TO 75TH PERCENTILE SNOW AMOUNTS FOR THE
MOUNTAINS, HOWEVER, ARE CLOSER TO 5 TO 10 INCHES FOR THE NORTHERN
MOUNTAINS, LOCALLY UP TO 15 INCHES IN THE BEAR RIVER RANGE, DUE TO
PREVIOUSLY MENTIONED "WARM" MID-LEVELS. ENSEMBLE SYSTEMS ARE
LIKELY TO COME INTO BETTER AGREEMENT IN THE NEXT FEW CYCLES ON THE
POSITION OF THE JET AND THE RESULTING IMPACTS ON THE BEEHIVE
STATE.
SOMETHING WE CAN SAY WITH CONFIDENCE...UNLESS THE GUIDANCE CHANGES
SIGNIFICANTLY, THE THREAT OF VALLEY SNOW, PARTICULARLY FOR THE
VALLEY FLOORS OF NORTHERN UTAH IS QUITE LOW FOR THE NEXT 7 DAYS
(LESS THAN 10% FOR THE WASATCH FRONT, LESS THAN 20% FOR THE CACHE
VALLEY AND OTHER COLDER, NORTHERN VALLEYS THAT COULD HAVE MORE
STUBBORN COLD POOLS).
AVIATION...KSLC
LIGHT, WESTERLY TO NORTHWESTERLY WINDS WILL
PERSIST UNTIL A GRADUAL TRANSITION TO SOUTHEASTERLY AROUND 03-05Z.
WINDS WILL LIKELY BECOME LIGHT AND VARIABLE AT TIMES, ESPECIALLY
DURING THE EVENING AND OVERNIGHT HOURS. VFR CONDITIONS WILL
PREVAIL WITH SCT-BKN HIGH CLOUDS.
REST OF UTAH AND SOUTHWEST WYOMING
WINDS WILL REMAIN LIGHT AND
TERRAIN-DRIVEN, WITH VFR CONDITIONS PREVAILING AND PASSING SCT-
BKN HIGH CLOUDS. ALTHOUGH A BRIEF PERIOD OF LIFR CIGS DEVELOPED
THIS MORNING AT KLGU, HIGH CLOUDS WILL LIMIT THIS POTENTIAL EARLY
MONDAY MORNING TO ONLY 20% BETWEEN 14-17Z.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
KRUSE/CUNNINGHAM
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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