637
FXUS65 KSLC 061043
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
343 AM MST TUE JAN 6 2026
KEY MESSAGES
- DRY AND MOSTLY SUNNY CONDITIONS BUILD IN TODAY.
- OUR NEXT STORM MOVES IN WEDNESDAY AFTERNOON BRINGING MOUNTAIN AND
VALLEY SNOW ACROSS UT THROUGH THURSDAY, WITH THE EXCEPTION OF LOWER
WASHINGTON COUNTY.
- THERE IS ROUGHLY A ~50% CHANCE OF LAKE EFFECT SNOW TO DEVELOP
THURSDAY FOR THE MAJORITY OF THE SALT LAKE VALLEY. ANOTHER SHOT AT
LAKE EFFECT SNOW MAY DEVELOP FRIDAY MORNING, THOUGH THIS REMAINS
UNCERTAIN.
- HIGH PRESSURE BUILDS IN FOLLOWING THIS SYSTEM AND WILL LAST
THROUGH THE REMAINDER OF THIS FORECAST, PERHAPS EVEN BEYOND.
UNFORTUNATELY, THIS WOULD FAVOR THE DEVELOPMENT OF VALLEY
INVERSIONS.
DISCUSSION
GENERALLY WEAK, WESTERLY FLOW WILL PERSIST TODAY AS
TRANSIENT RIDGING BUILDS IN BETWEEN SYSTEMS. OUTSIDE OF A WEAK UPPER
SHORTWAVE TROUGH TRAVERSING NORTHERN UT WHICH MAY BRING LIGHT AND
ISOLATED MOUNTAIN SNOW TO THE BEAR RIVER RANGE THIS MORNING,
CONDITIONS SHOULD REMAIN DRY STATEWIDE THROUGH WEDNESDAY MORNING.
COME WEDNESDAY AFTERNOON/EVENING, A SHORTWAVE TROUGH WILL SLIDE
NORTHWEST ACROSS BAJA CALIFORNIA INTO THE DESERT SOUTHWEST. AS THIS
IS OCCURRING, A LONGWAVE UPPER TROUGH WILL DIVE SOUTHEAST FROM THE
PACIFIC NW. AS THIS OCCURS, BOTH TROUGHS WILL GRADUALLY PHASE
TOGETHER OVER TIME AND WITH EASTERN EXTENT, CAUSING THE TROUGH TO
DEEPEN AND PUSH FURTHER SOUTH BEFORE FULLY ACCELERATING EAST. THE
EVOLUTION OF THIS TROUGH IS SIGNIFICANT FOR THIS EVENT AS IT WILL
ASSIST IN PULLING COLDER AIR FURTHER SOUTH, BRINGING TEMPERATURES AT
700MB PERHAPS AS LOW AS -16C TO -17C, WHICH SERVES AS A PROXY FOR
VALLEY SNOW, WHERE -7C IS WHEN CONDITIONS BECOME FAVORABLE.
UPPER LEVEL DIFFLUENCE AHEAD OF THE TROUGH IS EXPECTED TO REMAIN
SOMEWHAT ON THE WEAKER END WEDNESDAY AFTERNOON DUE TO THE TROUGH NOT
HAVING FULLY EJECTED YET WITH STRONGER UPPER LEVEL WINDS REMAINING
ON THE BACK SIDE OF THE TROUGH (WEST). AS SUCH, ASCENT WILL REMAIN
SOMEWHAT LIMITED WITHIN THE DIFFLUENT REGION AHEAD OF THE TROUGH
KEEPING POPS SOMEWHAT LOWER ACROSS LOWER ELEVATIONS VERSUS
OROGRAPHICALLY FAVORED REGIONS WITHIN A SOUTHWESTERLY FLOW REGIME.
ADDITIONALLY, MASS RESPONSE APPEARS TO BE SOMEWHAT ON THE WEAKER
SIDE PERHAPS YIELDING LESSER QUALITY SURFACE MOISTURE KEEPING LOWER
ELEVATION AREAS ON THE DRIER SIDE INITIALLY. POPS ACROSS MOST OF
NORTHERN UT LOWER ELEVATION LOCATIONS WILL GENERALLY MAX OUT AROUND
40% WEDNESDAY AFTERNOON.
LATER WEDNESDAY EVENING INTO THURSDAY MORNING, A FRONTAL BOUNDARY
WILL SWEEP ACROSS NORTHERN UT AND WILL USHER IN NORTHWESTERLY WINDS.
A NOTEWORTHY INCREASE IN POPS WILL ACCOMPANY THIS AS THE FRONTAL
BOUNDARY PROVIDES SOMEWHAT STRONGER ASCENT AS IT PUSHES THROUGH. THE
MAIN EVENT WILL BE A DIRECT RESULT OF THE COLD NORTHWEST FLOW
PATTERN THAT DEVELOPS IN ITS WAKE, BRINGING MOUNTAIN SNOWFALL TO ALL
OF OUR MOUNTAINS, WITH POTENTIALLY SIGNIFICANT MOUNTAIN SNOWFALL
ACROSS NORTHERN UT, AND VALLEY SNOWFALL ACROSS THE MAJORITY OF THE
STATE.
REGARDING VALLEY SNOWFALL, OVERALL AMOUNTS REMAIN UNCERTAIN DUE TO
INCONSISTENCIES REGARDING WHEN OUR UPPER LEVEL WINDS CLOCK TO
NORTHERLY AND SHUT OFF THE SNOWFALL AS WELL AS MOISTURE QUALITY.
CURRENTLY, THE ENSEMBLE MEAN SNOW ACCUMULATION AT KSLC SITS AROUND 3-
4" WITH A RANGE SPANNING FROM NOTHING TO OVER 10". HI-RES MODELS ARE
STILL SOMEWHAT OUTSIDE OF THE TIME RANGE FOR THIS EVENT, FORCING US
TO RELY ON GLOBAL MODELS FOR THIS CYCLE. AS SUCH, ITS WORTH NOTING
THAT GRID SPACING/SMOOTHING WITHIN THESE MODELS MAY GENERATE SOME
OUTLIERS THAT PRODUCE HIGH-END SOLUTIONS. HOWEVER, THIS EVENT DOES
POSSESS A FEW "BOOM-OR-BUST" SCENARIOS. LAKE EFFECT SNOW GUIDANCE
DOES HINT THAT NORTHWESTERLY FLOW HANGS ON THROUGH THE MAJORITY OF
THURSDAY, PERHAPS WITH A BRIEF LULL IN THE EVENING, BEFORE TURNING
BACK ON FOR THE MAJORITY OF FRIDAY MORNING. IF THIS SCENARIO WERE TO
OCCUR, SOME HIGHER END SOLUTIONS MAY BE REALIZED. HOWEVER, THE
MAJORITY OF THE UNCERTAINTY WITH THIS FORECAST COMES FROM ENSEMBLE
DISAGREEMENT WITH THE UPPER TROUGH FORMING A CLOSED LOW TO OUR
SOUTH, SHOWN IN ROUGHLY ~30% OF ENSEMBLE GUIDANCE AND FAVORED MOSTLY
BY THE EURO. IF THIS WERE TO OCCUR, WINDS WOULD BECOME NORTHERLY
MUCH FASTER RESULTING IN SNOWFALL SHUTTING OFF QUICKER THAN EXPECTED
AND REALIZING THE LOWER SNOWFALL AMOUNTS. DETAILS WILL BE IRONED OUT
OVER THE NEXT COUPLE DAYS AS HI-RES GUIDANCE BEGINS REACHING THIS
TIMEFRAME.
REGARDING MOUNTAIN SNOWFALL, A SIMILAR SCENARIO EXISTS TO THE ONE
DISCUSSED ABOVE WHERE THE OVERALL DURATION OF NORTHWEST FLOW IS
QUITE SIGNIFICANT FOR HOW MUCH SNOW WILL ACTUALLY FALL. FOR EXAMPLE,
LOCATIONS SUCH AS ALTA AND BRIGHTON IN THE UPPER COTTONWOODS WHICH
ARE TYPICALLY FAVORED IN A NORTHWEST FLOW REGIME GENERALLY RANGE
FROM LESS THAN 10" TO AMOUNTS IN EXCESS OF 24" ON THE EXTREME HIGH
END. OTHERWISE, MOST OF OUR OTHER NORTHERN UT MOUNTAINS WILL SEE
GENERALLY 6-12" OF SNOW FROM THIS EVENT. REGARDING OUR CENTRAL AND
SOUTHERN UT MOUNTAINS, TOTALS REMAIN UNCERTAIN AS TOTALS ARE QUITE
SENSITIVE TO THE OVERALL EVOLUTION OF THE AFOREMENTIONED TROUGH AND
IF IT DEVELOPS A CLOSED LOW.
FOLLOWING THIS SYSTEM, A NOTABLY DRY PERIOD APPEARS TO DEVELOP AS A
STRONG RIDGE OF HIGH PRESSURE BUILDS IN OVER MUCH OF THE WEST. WITH
WEAK FLOW ALOFT EXPECTED, AND PERHAPS SNOWFALL EXISTING ON THE
VALLEY FLOORS, THE DEVELOPMENT OF VALLEY INVERSIONS APPEAR QUITE
LIKELY AT THIS TIME. GRANTED, STRENGTH AND DURATION OF THESE
INVERSIONS WILL BE QUITE DEPENDENT ON HOW MUCH SNOW EXISTS ON THE
VALLEY FLOORS, RESULTING IN A CATCH22 SITUATION FOR THOSE WHO ARE
VALLEY SNOW DEPRIVED.
AVIATION...KSLC
SOUTH WINDS WITH VFR CONDITIONS WILL PREVAIL
THROUGH THE TAF PERIOD. THERE IS A 30% CHANCE WINDS SHIFT TO THE
NORTHWEST DURING THE 22-02Z TIMEFRAME, HOWEVER SPEEDS WILL REMAIN
LESS THAN 10 KTS.
REST OF UTAH AND SOUTHWEST WYOMING
IN GENERAL, VFR CONDITIONS ARE
EXPECTED TO PREVAIL ACROSS THE AREA THROUGH THE TAF PERIOD WITH
WINDS GENERALLY DRIVEN BY LOCAL DIURNAL FLOWS. THERE IS A 10% CHANCE
FOR SHALLOW FOG TO REDUCE VISIBILITY INTO THE LIFR RANGE AT KLGU
THROUGH 16Z THIS MORNING.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
PUBLIC...WORSTER
AVIATION...SEAMAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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