445
FXUS65 KSLC 132310
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
410 PM MST MON JAN 13 2025
SYNOPSIS
A COLD AIRMASS WILL REMAIN IN PLACE ACROSS THE REGION
THROUGH AT LEAST MIDWEEK WHEN HIGH PRESSURE WILL MOVE IN, BRINGING
DRY, STABLE CONDITIONS. THE NEXT WEATHER SYSTEM AND ASSOCIATED
COLD FRONT IS POISED TO MOVE INTO THE REGION IN THE LATE FRIDAY TO
SATURDAY TIMEFRAME, POTENTIALLY BRINGING THE COLDEST AIR SO FAR
THIS SEASON TO THE REGION BY NEXT WEEKEND.
SHORT TERM (THROUGH 12Z WEDNESDAY)
A NORTHERLY FLOW ALOFT REMAINS
IN PLACE OVER UTAH THIS AFTERNOON IN BETWEEN A MEAN LONGWAVE TROUGH
OVER THE CENTRAL/EASTERN CONUS AND A STRONG RIDGE BUILDING INTO THE
WEST COAST. A WEAK DISTURBANCE EMBEDDED IN THE FLOW IS CURRENTLY
NOTED OVER NORTHERN UTAH, AND WHICH SHOULD TRACK SOUTH THROUGH THE
NIGHT. LIGHT SNOW SHOWERS ARE ASSOCIATED WITH THIS DISTURBANCE.
EXPECT JUST MINOR SNOW ACCUMULATIONS IN THE NORTHERN AND CENTRAL
UTAH MOUNTAINS AND VERY LITTLE OR NO ACCUMULATION IN THE VALLEYS.
HOWEVER, AS HAS BEEN THE CASE OF LATE, SOME MODELS HAVE
UNDERESTIMATED THE PRECIPITATION POTENTIAL WITH THIS DISTURBANCE.
EXPECT THE SNOW SHOWERS TO GRADUALLY TAPER OFF TONIGHT AS SAID WAVE
SHIFTS SOUTH. PARTIAL CLEARING TONIGHT WILL LEAD TO COLD OVERNIGHT
TEMPERATURES ONCE AGAIN, WITH A POTENTIAL FOR FOG, MAINLY IN THE
TYPICALLY FAVORED AREAS (CACHE VALLEY, WASATCH BACK, BEAR LAKE/BEAR
RIVER VALLEY).
YET ANOTHER EMBEDDED DISTURBANCE IS EXPECTED TO CARVE INTO UTAH
TOMORROW AFTERNOON AS A REX BLOCK DEVELOPS UPSTREAM OFF THE WEST
COAST. AGAIN, LIMITED MOISTURE WILL BE IN PLACE, AND MODELS ARE
SHOWING VERY LITTLE TO NO PRECIPITATION WITH THIS WAVE. SUSPECT
MODELS MAY BE A BIT UNDERDONE ONCE AGAIN, BUT REGARDLESS, SNOW
AMOUNTS SHOULD REMAIN MINOR WITH VERY LITTLE IF ANY IMPACTS.
LONG TERM (AFTER 12Z/5AM WEDNESDAY)
BY WEDNESDAY MORNING, THE MID-
LEVEL RIDGE WILL BROADEN ACROSS THE WESTERN U.S. AND HELP TO
MAINTAIN DRY CONDITIONS ALONGSIDE SLOWLY WARMING TEMPERATURES ACROSS
THE FORECAST AREA THROUGH FRIDAY. AS TEMPERATURES WARM OVERHEAD
UNDER THE INFLUENCE OF THE HIGH, VALLEY INVERSIONS WILL STRENGTHEN,
ESPECIALLY ON WEDNESDAY AND THURSDAY AFTERNOON. IT IS UNLIKELY THERE
WILL BE ENOUGH TIME UNDER VALLEY INVERSIONS FOR PARTICULATES TO
ACCUMULATE BEFORE OUR NEXT STORM SYSTEM ARRIVES AT THE DOORSTEP.
TANGENTIALLY RELATED TO VALLEY INVERSIONS, A VERY REAL POTENTIAL
OUTCOME FROM THIS SETUP COULD BE LIMITED WARMING FOR THE VALLEYS
INSTEAD OF SEEING GRADUALLY WARMING TEMPERATURES THROUGH FRIDAY. IN
GENERAL, WE SHOULD SEE TEMPERATURES RISE 3-5 DEGREES FROM WEDNESDAY
INTO THURSDAY, HOWEVER, IF THE INVERSION BECOMES STRONG ENOUGH, WE
MAY ONLY SEE 1-2 DEGREES OF WARMING OR NO WARMING AT ALL.
BY FRIDAY, OVERHEAD TEMPERATURES BEGIN COOLING GRADUALLY AS OUR NEXT
STORM SYSTEM APPROACHES FROM THE NORTH. THE NET EFFECT OF THIS
COOLING WILL BE TO ALLEVIATE VALLEY INVERSIONS AND INTRODUCE AT
LEAST SOME WARMING IF NONE HAS BEEN SEEN BY THIS POINT. HEADING
THROUGH LATE FRIDAY AND INTO SATURDAY, ENSEMBLE GUIDANCE IS IN GOOD
AGREEMENT ON INTRODUCING A TROUGH INTO THE REGION, HOWEVER, THERE IS
STILL A SIGNIFICANT AMOUNT OF UNCERTAINTY REVOLVING AROUND HOW THIS
TROUGH PROGRESSES THROUGH THE REGION, MAINLY WITH THE OVERALL DEPTH
OF THE FEATURE AS IT PUSHES THROUGH. AS SUCH, PRECIPITATION
POTENTIAL HAS QUITE A LARGE RANGE BETWEEN THE 25TH TO 75TH
PERCENTILE, AND MUCH LARGER BETWEEN THE 10TH TO 90TH PERCENTILE.
CURRENT MODEL GUIDANCE SHOWS THE HIGHEST POTENTIAL FOR PRECIPITATION
ACROSS THE NORTHERN AND CENTRAL UTAH MOUNTAINS, AS WELL AS THE
WASTACH BACK. TEMPERATURES ASSOCIATED WITH THIS TROUGH ARE LOOKING
TO BE SOME OF THE COLDEST POTENTIAL TEMPERATURES WE'VE SEEN THIS
SEASON, BUT WITH THE TROUGH DEPTH UNCERTAINTY ALSO COMES UNCERTAINTY
IN THE SURFACE TEMPERATURE FORECAST. FOR EXAMPLE, NBM 10TH TO 90TH
PERCENTILE HIGH TEMPERATURE OUTPUT FOR KSLC RANGES FROM FROM AROUND
20 TO 40 DEGREES FOR BOTH SUNDAY AND MONDAY... 20 DEGREES
DIFFERENCE! LOTS TO HONE IN ON WITH THIS FORECAST.
BIG PICTURE TAKEAWAY IS THAT;
1) NORTHERN AND CENTRAL UTAH MOUNTAINS, AS WELL AS THE WASATCH BACK,
WILL BE FAVORED FOR ANOTHER ROUND OF SNOWFALL.
2) THINGS COULD GET COLD LATE IN THE UPCOMING WEEKEND ACROSS THE
FORECAST AREA, ESPECIALLY FOR THE NORTHEASTERN PORTION OF THE
FORECAST AREA.
3) THE PRECIPITATION FORECAST HAS A WIDE RANGE OF POSSIBLE OUTCOMES
DUE TO THE UNCERTAINTY WITH THE DEPTH OF THE SYSTEM AS IT PASSES
OVER UTAH/ SOUTHWEST WYOMING. THIS WILL BE DIALED AS MODELS
(HOPEFULLY) COME INTO GREATER AGREEMENT.
AFTER THIS SYSTEM PASSES, ENSEMBLE GUIDANCE MAINTAINS AN UPSTREAM
RIDGE OVER THE PACNW REGION. FOR US, IF THIS RIDGE SHIFTS FARTHER
EAST, WE WILL SEE THE AREA GET CUTOFF FROM ANY POTENTIAL STORMS. IF
IT TRACKS FARTHER WEST, WE COULD SEE THE DOOR OPEN UP FOR MORE COLD
AIR AND POTENTIAL STORM SYSTEMS.
AVIATION...KSLC
MOSTLY VFR CONDITIONS WILL PERSIST FOR THE KSLC
TERMINAL THROUGH THE PERIOD, BUT A FEW BRIEF SNOW SHOWERS COULD DROP
VIS TO MVFR OR IFR THROUGH ~02Z. LOWERED CIGS WILL CREATE MOUNTAIN
OBSCURATION THROUGH ~06Z BEFORE CONDITIONS START TO CLEAR OVERNIGHT.
THE REMAINDER OF THE PERIOD WILL BE DRY WITH LIGHT NORTHERLY WINDS
TRANSITIONING TO LIGHT SOUTHERLY FLOW OVERNIGHT.
REST OF UTAH AND SOUTHWEST WYOMING
ISOLATED AND BRIEF SNOW
SHOWERS ACROSS THE NORTHERN AIRSPACE WILL CREATE INTERMITTENT
MVFR/IFR CONDITIONS THROUGH ~02Z. LOWERED CIGS WILL ALSO CONTRIBUTE
TO MOUNTAIN OBSCURATION THROUGH ~06Z. SKIES WILL GRADUALLY CLEAR
OVERNIGHT WITH DRYING CONDITIONS. WINDS WILL BE LIGHT AND VARIABLE.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
CHENG/WEBBER/MAHAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE
VISIT... HTTP://WEATHER.GOV/SALTLAKECITY
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