041
FXUS65 KSLC 122301
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
401 PM MST SUN JAN 12 2025
SYNOPSIS
A COLD AIRMASS WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH AT LEAST MIDWEEK.
SHORT TERM (THROUGH 12Z TUESDAY)
UTAH REMAINS UNDER A COLD
NORTHERLY FLOW ALOFT THIS AFTERNOON, IN BETWEEN A TROUGH OVER THE
CENTRAL CONUS AND A RIDGE BUILDING JUST OFF THE WEST COAST. SEVERAL
DISTURBANCES EMBEDDED IN THE NORTHERLIES WILL RIPPLE THROUGH UTAH
THROUGH TOMORROW EVENING. ONE SUCH DISTURBANCE IS CROSSING THE AREA
CURRENTLY, AIDING SNOW SHOWER ACTIVITY ACROSS THE AREA THIS
AFTERNOON. EXPECT TO SEE THE SHOWERS WIND DOWN THIS EVENING UNTIL
THE NEXT DISTURBANCE MOVES THROUGH LATE TONIGHT INTO EARLY TOMORROW
MORNING, FOLLOWED BY YET A THIRD DISTURBANCE LATE TOMORROW AFTERNOON
INTO TOMORROW EVENING.
NONE OF THE MODELS ARE PRODUCING MORE THAN A FEW TINY AREAS OF LIGHT
SNOW WITH THE DISTURBANCES TONIGHT AND TOMORROW. HOWEVER, MODELS
HAVE NOT HAD A VERY GOOD HANDLE WITH RESPECT TO PRECIPITATION
LATELY. DID INCREASE POPS SLIGHTLY OVER NBM, MAINLY OVER THE
MOUNTAINS, BUT HAVE SOME CONCERNS THAT THESE DISTURBANCES MAY
OVERPERFORM, SO CANNOT RULE OUT THE POTENTIAL FOR SOME LIGHT
ACCUMULATING SNOW, WHICH COULD AFFECT BOTH THE MORNING AND AFTERNOON
COMMUTES TOMORROW. OTHERWISE, IF IT ENDS UP JUST BEING MOSTLY CLEAR
TO PARTLY CLOUDY, ESPECIALLY WITH TONIGHT'S DISTURBANCE (AS MODELS
SUGGEST), THEN THERE WILL BE A POTENTIAL FOR VALLEY FOG ACROSS PARTS
OF NORTHERN AND CENTRAL UTAH.
LONG TERM (AFTER 12Z/5AM TUESDAY)
A COLD AND MOSTLY DRY PERIOD
WILL BE THE THEME FOR NEXT WEEK. NORTHERLY FLOW ALOFT WILL KEEP
TEMPERATURES ~5 DEGREES BELOW NORMAL FOR TUESDAY. TEMPERATURES WILL
GRADUALLY WARM THROUGHOUT THE WEEK AS THE TROUGH RESPONSIBLE FOR
THIS NORTHERLY FLOW BEGINS TO SPLIT. THIS WILL MOVE THE COLDEST OF
THE AIRMASS TO THE EAST WHILE CUTTING OFF AN AREA OF LOW PRESSURE
ALONG THE CALIFORNIA COAST. HIGH PRESSURE WILL BUILD TO THE NORTH OF
THIS LOW ACROSS THE PNW CREATING A REX BLOCK PATTERN THAT WILL BLOCK
INCOMING TROUGHS, TEMPORARILY.
ALL ENSEMBLE MEMBERS DEPICT A HIGHLY AMPLIFIED RIDGE BUILDING INTO
THE EASTERN PACIFIC UP THROUGH ALASKA. THIS WILL LIKELY DISLODGE A
VERY COLD AIRMASS INTO THE INTERIOR US. 49% OF THE GUIDANCE HAS A
SLIGHTLY FURTHER WESTERLY TRAJECTORY FOR THIS COLD AIRMASS AND
ASSOCIATED TROUGH, BUT THE OTHER 51% SHIFT THE COLDEST AIR TO OUR
EAST. THESE PATTERNS TEND TO TREND TOWARDS THE FURTHER EAST SOLUTION
AS THESE VERY ANOMALOUSLY COLD DENSE AIRMASSES HAVE A DIFFICULT TIME
MOVING TOO FAR WEST OF THE CONTINENTAL DIVIDE. THIS IS WHY THERE IS
SUCH A LARGE SPREAD IN THE H7 TEMPERATURES SOLUTIONS WITHIN THE
ENSEMBLE MEMBERS. THE 25TH-75TH PERCENTILE RANGES FROM -14C TO -20C.
REGARDLESS, WE SHOULD SEE COLDER THAN NORMAL CONDITIONS BY THE END
OF THE WEEK INTO THE WEEKEND WITH A CHANCE FOR SOME LIGHT DRY SNOW
ASSOCIATED WITH THE BAROCLINIC ZONE. GIVEN THE CONTINENTAL NATURE OF
THE AIRMASS, THERE WON'T BE MUCH MOISTURE TO WORK WITH BUT IT SHOULD
BE COLD ENOUGH TO ALLOW FOR EFFICIENT ACCUMULATION FOR ANY MOISTURE
THAT IS SQUEEZED OUT.
AVIATION...KSLC
LIGHT SNOW SHOWERS ARE LIKELY TO DISSIPATE AFTER
00Z, BUT MAY PRODUCE BRIEF PERIODS OF MVFR CIGS UNTIL THEN. FOG
BECOMES A POSSIBILITY OVERNIGHT IF SKIES CLEAR, THOUGH THIS REMAINS
A LOW CONFIDENCE FORECAST. THE MOST LIKELY TIMING FOR FOG, IF IT
DOES DEVELOP, WOULD BE BETWEEN 13-16Z, WITH CURRENTLY A ~25% CHANCE
FOR IFR CONDITIONS AND A ~10% CHANCE FOR DENSE FOG (VIS < 1/4SM).
WINDS ARE EXPECTED TO BE LIGHT AND VARIABLE OVERNIGHT, THOUGH WILL
SLIGHTLY FAVOR A NORTHERLY DIRECTION.
REST OF UTAH AND SOUTHWEST WYOMING
LIGHT SNOW SHOWERS ARE LIKELY
TO DISSIPATE AFTER 02Z ACROSS MOST AREAS, THOUGH MAY LINGER AROUND
KBCE UNTIL 06-07Z. IF SKIES CLEAR OVERNIGHT, FOG WILL LIKELY DEVELOP
ACROSS MANY VALLEY LOCATIONS, WITH THE HIGHEST CHANCES AT KLGU,
KEVW, AND KHCR. AT THESE THREE SITES IN PARTICULAR, DENSE FOG AND
LIFR CONDITIONS ARE LIKELY BETWEEN ROUGHLY 09-17Z.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
CHENG/MAHAN/CUNNINGHAM
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