513
FXUS65 KSLC 231005
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
305 AM MST TUE DEC 23 2025
KEY MESSAGES
- NEAR RECORD TO RECORD TEMPERATURES WILL CONTINUE THROUGH
THURSDAY.
- THERE IS A 35% CHANCE WIND GUSTS IN EXCESS OF 45 MPH WILL OCCUR
ACROSS WESTERN UTAH NEAR THE NEVADA BORDER WEDNESDAY AFTERNOON
AND EVENING.
- 6 TO 12 INCHES OF SNOW IS EXPECTED ACROSS THE SOUTHERN
MOUNTAINS ABOVE 8500 FEET AND THE WESTERN UINTA MOUNTAINS ABOVE
9000 FEET WEDNESDAY INTO LATE THURSDAY.
- AN AREA OF MODERATE TO HEAVY RAIN WILL OCCUR ACROSS SOUTHERN
UTAH BELOW 8000 FEET WEDNESDAY INTO THURSDAY. EXPECT ENHANCED
RUNOFF ACROSS THIS AREA, WITH ALL STREAMS, SLOT CANYONS, AND
OTHER WATERWAYS RUNNING HIGH.
- THE UNSETTLED PATTERN WILL CONTINUE WITH GRADUALLY FALLING SNOW
LEVELS, REACHING AS LOW AS 6000 FEET BY FRIDAY EVENING AND
CONTINUING TO FALL TOWARD VALLEY FLOORS BY SATURDAY MORNING.
ANOTHER 6 TO 12 INCHES OF SNOW WILL OCCUR ACROSS MOST UTAH
MOUNTAINS FRIDAY INTO SATURDAY.
- THERE IS A 30% CHANCE OF MEASURABLE SNOW FOR THE VALLEY FLOORS
OF NORTHERN UTAH FRIDAY NIGHT INTO SATURDAY MORNING.
DISCUSSION
IT IS ANOTHER EXTREMELY WARM OVERNIGHT PERIOD (FOR
THE COOL SEASON) FOR MANY LOCATIONS ACROSS NORTHERN AND WESTERN
UTAH. THE SALT LAKE CITY AIRPORT BROKE THE ALL TIME HIGH MINIMUM
TEMPERATURE FOR DECEMBER AND TIED THE ALL TIME HIGH MINIMUM FOR
THE ENTIRE WINTER SEASON (DECEMBER THROUGH FEBRUARY) ON DECEMBER
22. SO FAR, THE LOW AFTER MIDNIGHT HAS FALLEN ONLY TO 58F. IT IS
SIGNIFICANTLY LESS WINDY THAN IT WAS AT THIS TIME LAST NIGHT, SO
THERE IS STILL SOME HOPE THE NORTHERN AND WESTERN VALLEYS WILL
DECOUPLE THROUGH 9 AM. IF THIS DOESN'T HAPPEN, WILL AGAIN NEED TO
UPDATE THE FORECAST AND PUSH THE HIGH TEMPERATURES AT OR ABOVE THE
95TH PERCENTILE.
EARLY MORNING UPPER AIR AND SATELLITE ANALYSIS INDICATES A
STRONG, ACTIVE JET PERSISTS ACROSS THE SOUTHWESTERN UNITED STATES.
SEMI-TROPICAL MOISTURE ASSOCIATED WITH THE EASTERN PACIFIC ITCZ IS
BEING ENTRAINED INTO THIS JET CIRCULATION. AN UPPER LEVEL TROUGH
IS APPROACHING THE PACIFIC COAST. LOOKING AT THE CURRENT
MESOANALYSIS ACROSS THE BEEHIVE STATE, PRECIPITABLE WATER VALUES
ARE QUITE LOW, AROUND 0.20 INCHES OR SO FOR MOST OF SOUTHERN UTAH.
AS A 140KT+ JET MAX ROUNDS THE BASE OF THE TROUGH THIS EVENING
INTO TONIGHT, A SHORTWAVE EJECTING AHEAD OF THE MAIN CIRCULATION
WILL SHIFT ACROSS THE AREA EARLY TO MID-WEDNESDAY MORNING. THIS IS
LOOSELY ASSOCIATED WITH THE EDGE OF THE DEEPER MOISTURE FROM THE
ITCZ, AROUND 99.5TH PERCENTILE FOR THE NAEFS CLIMATOLOGY. DEEP
MOISTURE ADVECTION WILL CONTINUE, EXCEEDING THE MAX IN THE NAEFS
CLIMATOLOGY BY WEDNESDAY EVENING.
MEANWHILE, THE UPPER LEVEL TROUGH WILL CONTINUE TO SHIFT EASTWARD,
WITH PREFERENTIAL JET DYNAMICS SHIFTING TOWARD SOUTHWESTERN UTAH
WEDNESDAY AFTERNOON. THE PERIOD OF HEAVIEST PRECIPITATION IS
EXPECTED FROM ROUGHLY 18Z WEDNESDAY THROUGH 12Z THURSDAY. THE BEST
FORCING FOR PRECIPITATION WILL SHIFT EAST OF THE AREA THURSDAY
AFTERNOON INTO THURSDAY EVENING.
WHILE 700MB WINDS APPROACH 50 KTS ACROSS WESTERN UTAH WEDNESDAY
AFTERNOON AND EVENING, DEEP MOISTURE COMBINED WITH EXTENSIVE CLOUD
COVER WILL LIKELY PRECLUDE WIDESPREAD AREAS OF WIND ADVISORY
CRITERIA ACROSS WESTERN UTAH. CURRENT FORECAST IS FOR AN
APPROXIMATE 35% CHANCE OF WIND GUSTS IN EXCESS OF 45 MPH FOR
SEVERAL HOURS ALONG THE UTAH/NEVADA BORDER. GIVEN THIS LOW
PROBABILITY, NO WIND HEADLINES WILL BE ISSUED WITH THIS PACKAGE.
EARLY RUNS OF THE CAMS SUGGEST HOURLY RATES, PARTICULARLY IN
AREAS PRONE TO SOUTHERLY UPSLOPE, WILL RANGE FROM 0.10-0.40" (25TH
TO 75TH PERCENTILE) WITH A 10% CHANCE OF HOURLY RATES IN EXCESS
OF 0.50" IN EMBEDDED CONVECTION. A PORTION OF THE CAMS ARE
STRUGGLING TO SATURATE THE LOWEST LEVELS ACROSS THE ST. GEORGE
METRO, HOWEVER, THINK WITH THE DEPTH OF THE MOISTURE WITH THIS
SYSTEM, THIS WILL BE OVERCOME BY WEDNESDAY EVENING AT THE LATEST.
THE SNOW LEVEL WILL START AROUND 9500 FEET WEDNESDAY AFTERNOON AND
FALL TO NEAR 8500 FEET THROUGH THURSDAY MORNING ACROSS THE
SOUTHERN UTAH MOUNTAINS. SNOW LEVELS WILL FALL AS LOW AS 7500 FEET
IN HEAVY PRECIPITATION. THE SOUTHERN MOUNTAINS ABOVE 8500 FEET
WILL SEE 6 TO 12 INCHES (25TH TO 75TH PERCENTILE) THROUGH
THURSDAY NIGHT. ISSUED A WINTER WEATHER ADVISORY FOR THESE
LOCATIONS WITH THIS PACKAGE.
STORM TOTAL PRECIPITATION (LARGELY RAIN BELOW 8000-8500 FEET,
SNOW WATER EQUIVALENT ABOVE 8500 FEET) FOR SOUTHWESTERN UTAH WILL
RANGE FROM 0.40-1.00" (25TH TO 75TH PERCENTILE) FOR LOWER
WASHINGTON COUNTY, 0.75-1.75" (25TH TO 75TH PERCENTILE) FOR MUCH
OF THE REMAINDER OF SOUTHWESTERN UTAH BY THURSDAY EVENING. THERE
IS A 10 PERCENT CHANCE STORM TOTALS WITH EXCEED 2.50" FOR THE PINE
VALLEYS EASTWARD TO ZION NATIONAL PARK AND OTHER AREAS WITH
PREFERENTIAL UPSLOPE IN SOUTHWESTERLY FLOW.
ALL AREA STREAMS, NORMALLY DRY WASHES, SLOT CANYONS, AND OTHER
WATERWAYS WILL BE RUNNING WEDNESDAY THROUGH AT LEAST FRIDAY. THE
CURRENT FORECAST FROM THE COLORADO BASIN RIVER FORECAST CENTER FOR
THE NORTH FORK OF THE VIRGIN RIVER, FOR EXAMPLE, SHOWS A PEAK FLOW
OF AROUND 570 CFS (FROM A SMALL BASE FLOW AROUND 40 CFS) BY EARLY
THURSDAY MORNING. ANYONE WITH OUTDOOR PLANS IN THESE AREAS SHOULD
CONSIDER ALTERNATE PLANS OUTSIDE THESE WATERWAYS. THE WEATHER
PREDICTION CENTER CONTINUES TO OUTLOOK SOUTHWESTERN UTAH IN A
MARGINAL RISK FROM WEDNESDAY MORNING THROUGH THURSDAY EVENING,
MEANING THERE IS A GREATER THAN 5% CHANCE RAINFALL WILL EXCEED
FLASH FLOOD GUIDANCE WITH 25 MILES OF A POINT. WHILE THE THREAT
FOR FLASH FLOODING IS VERY LOW, CAMS DO INDICATE THE POTENTIAL FOR
EMBEDDED CONVECTION, SO WILL NEED TO MONITOR THIS THREAT FOR THE
BULK OF THE STORM.
WHILE THE SOUTHERN PART OF THE STATE WILL SEE THE HIGHEST
PRECIPITATION TOTALS WITH THIS LANDFALLING ATMOSPHERIC RIVER, SNOW
LEVELS WILL BE QUITE HIGH ACROSS NORTHERN AND CENTRAL UTAH,
LEADING TO RAIN IN MANY AREAS BELOW 9000-9500 FEET OR SO THROUGH
AT LEAST THURSDAY MORNING. EXPECT A GENERAL 0.15-0.40" (25TH TO
75TH PERCENTILE) OF RAIN FOR THE NORTHERN AND CENTRAL VALLEYS,
EXCEPT 0.40-0.75" (25TH TO 75TH PERCENTILE) FOR THE NORTHERN
WASATCH FRONT AND CACHE VALLEY. FOR THE WASATCH RANGE, EXPECT
AROUND 0.70-1.50" OF RAIN BELOW 9000-9500 FEET, SNOW WATER
EQUIVALENT FOR THOSE HIGHEST PEAKS THROUGH THURSDAY NIGHT. FOR
THE HIGH UINTAS ABOVE 9000 FEET, EXPECT 6 TO 12 INCHES OF SNOW
(25TH TO 75TH PERCENTILE) THROUGH THURSDAY NIGHT. ISSUED WINTER
WEATHER ADVISORY FOR THE WESTERN UINTA MOUNTAINS ABOVE 9000 FEET
WITH THIS PACKAGE.
ATTENTION THEN TURNS TO A COLDER UPPER LEVEL LOW AND LONGWAVE
TROUGH MAKING LANDFALL NEAR THE NORTHERN CALIFORNIA COAST BY
THURSDAY EVENING WHICH WILL BRING AN END TO THE RECORD
TEMPERATURES ACROSS THE REGION. AS THE TROUGH SHIFTS EASTWARD
FRIDAY, COLD AIR ADVECTION ASSOCIATED WITH THIS SYSTEM WILL SHIFT
INTO NORTHERN UTAH. SNOW LEVELS NEAR 8000 FEET THURSDAY EVENING
WILL FALL TO NEAR 6500 FEET BY FRIDAY MORNING AND TO NEAR VALLEY
FLOORS BY SATURDAY MORNING AS 700MB TEMPERATURES FALL FROM NEAR
-1C THURSDAY EVENING TO -8C BY SATURDAY MORNING.
THE MOST FOCUSED PERIOD OF PRECIPITATION ASSOCIATED WITH THIS
SECOND SYSTEM IS ASSOCIATED WITH A STRONG JET MAX CROSSING THE
REGION FRIDAY EVENING INTO EARLY SATURDAY MORNING. SHOWERS WILL
LINGER INTO THE EARLY AFTERNOON.
THE MOUNTAINS OF UTAH ARE A RELATIVELY EASY FORECAST FOR THIS
SECOND SYSTEM, WITH THE BULK OF THE HIGHER TERRAIN SEEING 6 TO 12
INCHES OF SNOW (25TH TO 75TH PERCENTILE). NO REAL SNOW LEVEL
ISSUES WITH THIS PART OF THE STORM. THE BIGGER QUESTION (AND ONE
THAT I KNOW IS ON A LOT OF PEOPLES' MINDS) IS THE POTENTIAL FOR
MEASURABLE SNOW FOR THE VALLEY FLOORS OF THE WASATCH FRONT. THERE
IS A PERIOD OF PRECIPITATION THAT OVERLAPS WITH LOWER SNOW LEVELS
IN A SUBSET OF THE GUIDANCE SATURDAY MORNING. THIS IS THE CRUX OF
THE ISSUE...WHETHER THE FORCING FOR PRECIPITATION MOVES EAST OF
THE VALLEYS PRIOR TO THE COLDEST AIR ARRIVING. NBM PROBABILITIES
FOR MEASURABLE SNOW FOR THE VALLEY FLOOR CONTINUE TO HOVER AROUND
30% FOR THE LOWEST PORTIONS OF THE WASATCH FRONT, INCREASING WITH
ELEVATION TO GREATER THAN 70% ABOVE ABOUT 4800 FEET. FORECASTING
THE OVERLAP BETWEEN THE COLD TEMPERATURES AND CESSATION OF
PRECIPITATION IS DIFFICULT THIS FAR OUT, BUT SOMETHING TO KEEP AN
EYE ON.
NO HEADLINES FOR THIS SECOND SYSTEM AT THIS TIME, THOUGH THE
CURRENT FORECAST WOULD LEAN TOWARD WINTER WEATHER ADVISORIES FOR
MOST MOUNTAIN AREAS OF UTAH FRIDAY INTO SATURDAY.
AVIATION...KSLC
SOUTHERLY WINDS AROUND 8-12KTS WILL CONTINUE,
WITH GUSTS TO ~25KTS LIKELY PICKING UP AFTER 18Z. A FEW HIGH-BASED
SHOWERS COULD ARRIVE AFTER 00Z WEDNESDAY WHICH COULD MAKE WINDS A
LITTLE SQUIRRELY, BUT THIS SHOULD BE RELATIVELY LOWER IMPACT. VFR
CONDITIONS WILL PREVAIL WITH BKN-OVC HIGH CLOUDS BRIEFLY LOWERING
TO AROUND 7000-9000FT TUESDAY EVENING.
REST OF UTAH AND SOUTHWEST WYOMING
GUSTY SOUTHERLY WINDS WILL
PICK UP AFTER ~18Z ACROSS MOST AREAS, WITH LARGELY GUSTS TO
25-35KTS EXPECTED. BKN-OVC MID- TO HIGH-CLOUDS WILL PERSIST ACROSS
THE AREA, WITH SOME RAINFALL MOVING INTO SOUTHWESTERN UT AFTER
23Z. THESE SHOWERS MAY BRING LOWER CIGS AROUND 3000FT TO KCDC AND
KSGU, AND MAY BRIEFLY ENHANCE SOUTHERLY WIND GUSTS (10% CHANCE OF
EXCEEDING 40KTS).
SLC WATCHES/WARNINGS/ADVISORIES
UT...WINTER WEATHER ADVISORY FROM 11 AM WEDNESDAY TO 11 PM MST
THURSDAY FOR UTZ112.
WINTER WEATHER ADVISORY FROM 5 AM WEDNESDAY TO 11 PM MST
THURSDAY FOR UTZ125.
WY...NONE.
KRUSE/CUNNINGHAM
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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