121
FXUS65 KSLC 111108
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
408 AM MST SAT JAN 11 2025
SYNOPSIS
A WINTER STORM WILL IMPACT NORTHERN AND CENTRAL UTAH
THIS WEEKEND, WITH COLD, DRY AIRMASS BUILDING INTO THE REGION FOR
EARLY NEXT WEEK.
SHORT TERM (THROUGH 12Z/5AM MONDAY)
A POSITIVELY TILTED
SHORTWAVE TROUGH IS CURRENTLY TRANSLATING THROUGH THE
INTERMOUNTAIN WEST, WITH THE ASSOCIATED LOW LEVEL BAROCLINIC ZONE
HAVING PASSED THROUGH NORTHERN UTAH OVERNIGHT, AND CURRENTLY
PUSHING INTO CENTRAL UTAH. A BAND OF GENERALLY LIGHT TO PERHAPS
MODERATE SNOW ACCOMPANIES THIS FEATURE, AND WILL BRING A PERIOD OF
ACCUMULATING SNOW TO SOUTHERN UTAH THIS MORNING. IN THE WAKE OF
THIS BAND, COLD AIR ALOFT IS SPREADING INTO NORTHERN UTAH
RESULTING IN A WINDOW OF SOMEWHAT FAVORABLE OROGRAPHIC FORCING
ALONG THE WASATCH RANGE. MOISTURE IS LIMITED WITH THIS SYSTEM, AND
THE FAVORABLE WINDOW FOR OROGRAPHIC FORCING WILL BE SOMEWHAT
LIMITED AS THE FLOW ALOFT TAKES ON A MORE NORTHERLY COMPONENT
THROUGH THE DAY TODAY, BUT EXPECT A FEW ADDITIONAL INCHES OF
ACCUMULATION THROUGH THE MORNING HOURS ALONG THE TERRAIN.
AS COLD AIR ALOFT SPREADS INTO THE REGION TODAY, (700MB TEMPS
NEAR OR BELOW -12C ACROSS MOST OF THE AREA BY THIS AFTERNOON), MAY
SEE OCCASIONAL CONVECTION DEVELOP OVER THE RELATIVELY WARM WATERS
OF THE GSL AND SPREAD INITIALLY INTO WESTERN SL COUNTY, BUT
EVENTUALLY INTO THE TOOELE VALLEY LATE TODAY INTO TONIGHT.
RELATIVELY DRY LOW LEVEL AIR WILL LIKELY LIMIT THE
ORGANIZATION/INTENSITY OF ANY LAKE INDUCED CONVECTION WHICH DOES
DEVELOP, AND EXPERIMENTAL GUIDANCE SHOWS ONLY A 40% CHANCE OF LAKE
EFFECT PRECIP DEVELOPING. SOMETHING TO MONITOR AS THE DAY
PROGRESSES, BUT CURRENTLY THINKING ANY LAKE INDUCED PRECIP WILL BE
TRANSIENT, INTERMITTENT AND OUTFLOW DOMINANT, AS OPPOSED TO A
WELL ORGANIZED STEADY-STATE BAND.
COOL NORTHERLY FLOW WILL PERSIST INTO THE DAY SUNDAY, WITH
MAX TEMPERATURES REMAINING IN THE LOW TO MID 30S ACROSS MOST
VALLEYS (ROUGHLY 5F BELOW CLIMO ACROSS THE NORTH AND CLOSER TO 10F
BELOW CLIMO ACROSS THE SOUTH). HAVE MAINTAINED A CHANCE FOR SNOW
SHOWERS ACROSS THE TERRAIN OF NORTHERN AND CENTRAL UTAH, WITH
MINIMAL ADDITIONAL ACCUMULATION.
LONG TERM (AFTER 12Z/5AM MONDAY)
A COOL, DRY NORTHERLY SYNOPTIC
FLOW WILL PREVAIL THROUGHOUT SOUTHWEST WYOMING AND UTAH MONDAY.
VALLEY LOW TEMPERATURES WILL DROP BELOW ZERO FOR PORTIONS OF FAR
NORTHEAST UTAH, WITH OTHER VALLEY LOCATIONS LIKELY IN THE SINGLE
DIGITS OR TEENS. HIGH TEMPERATURES WILL BE IN THE 20S AND 30S,
ROUGHLY 5F COOLER THAN NORMAL.
SIMILAR CONDITIONS WILL LIKELY LAST FURTHER INTO THE WEEK, WITH
ENSEMBLE GUIDANCE IN GOOD AGREEMENT ON A REX BLOCK, WITH HIGH
PRESSURE OFF THE PACNW COAST AND A CLOSED LOW OFF THE CALIFORNIA
AND BAJA CALIFORNIA COAST. THAT PATTERN WILL LIKELY HOLD FOR AT
LEAST SEVERAL DAYS. LIGHT WINDS AND COLD TEMPERATURES WILL RESULT
IN VALLEY INVERSIONS AND ASSOCIATED HAZE AS THAT BUILDS.
THERE IS SOME UNCERTAINTY IN THE POSITIONING OF THE REX BLOCK LATER
IN THE WEEK. MANY ENSEMBLE MEMBERS HAVE A SLIGHT RETROGRADE OF THAT
PATTERN, WHICH WOULD ALLOW FOR STORM SYSTEMS TO TRACK EAST OF THE
RIDGE INTO THE WESTERN U.S. THAT IS THE MOST LIKELY SCENARIO BY
FRIDAY INTO THE WEEKEND, BUT VALLEY INVERSIONS WITH THE REX BLOCK
COULD CONTINUE IF IT STAYS IN PLACE LONGER.
AVIATION...KSLC
SNOW SHOWERS WILL TAPER OFF THROUGH THE MORNING.
VFR CONDITIONS WILL PREVAIL, BUT MVFR CONDITIONS ARE LIKELY WITH
SNOW SHOWERS. NORTHWEST WINDS ARE LIKELY THROUGH THE DAY, WITH GUSTS
AROUND 20 MPH FROM AROUND 18-00Z.
REST OF UTAH AND SOUTHWEST WYOMING
SNOW SHOWERS FOR SOUTHWEST
WYOMING AND NORTHERN UTAH WILL TAPER OFF THROUGH THE MORNING. VFR
CONDITIONS WILL PREVAIL, BUT MVFR OR IFR CONDITIONS ARE LIKELY WITH
SNOW SHOWERS. ISOLATED SNOW SHOWERS WILL TRACK INTO SOUTHERN UTAH
LATER IN THE MORNING. NORTHWEST WINDS WILL INCREASE, WITH GUSTS TO
AROUND 30 KNOTS FOR SOUTHWEST WYOMING AND HIGHER ELEVATION PORTIONS
OF UTAH. WIND GUSTS WILL BE AROUND 20 KNOTS FOR MOST VALLEYS.
SLC WATCHES/WARNINGS/ADVISORIES
UT...WINTER WEATHER ADVISORY UNTIL 8 PM MST THIS EVENING FOR
UTZ110>113.
WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR UTZ117.
WY...NONE.
SEAMAN/WILSON
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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