312
FXUS65 KSLC 261454
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
854 AM MDT SUN MAR 26 2023
UPDATE
IMPRESSIVE AREA OF SNOWFALL CONTINUES TO MOVE EASTWARD
FROM THE SOUTH END OF THE CACHE VALLEY TO THE NORTH END OF THE
TOOELE AND SALT LAKE VALLEYS AS OF 845AM MDT. THIS BAND HAS
PRODUCED WIDESPREAD SNOWFALL RATES OF 1 TO 3 INCHES PER HOUR, WITH
REPORTS OF 4 INCHES OF SNOWFALL IN THE OGDEN METRO AREA. SLRS ARE
IN THE 20-30:1 RANGE, WITH EXTREMELY EFFICIENT ACCUMULATION OF
DENDRITES. THIS IS THE FIRST TIME IN MY CAREER I'VE SEEN SNOWFALL
THIS WIDESPREAD AND HEAVY, AND TO SEE IT SO POORLY REPRESENTED ON
AVAILABLE MODEL GUIDANCE. THE BAND APPEARS TO BE ASSOCIATED WITH
A SHORTWAVE AND LOW LEVEL FRONTOGENESIS AXIS TIED TO A SURFACE
FRONT EXTENDING SOUTHWARD FROM THE SOUTHEAST IDAHO SURFACE LOW.
GIVEN THE POOR MODEL REPRESENTATION, CONFIDENCE IS LOW ON HOW THIS
BAND WILL PROGRESS. MAJORITY OF GUIDANCE WEAKENS THE
FRONTOGENESIS AXIS BY 18Z, AND THEREFORE THE BAND SHOULD WEAKEN AT
THE SAME TIME. WILL CONTINUE TO NOWCAST AND UPDATE AS NEEDED.
SYNOPSIS
LOW PRESSURE OVER THE AREA WILL MAINTAIN COOL AND
UNSETTLED CONDITIONS TODAY WITH SCATTERED SNOW SHOWERS ACROSS THE
AREA TODAY INTO TONIGHT. A BRIEF BREAK IN THE WEATHER IS EXPECTED BY
LATE MONDAY AND CONTINUING INTO TUESDAY BEFORE INCREASING SOUTHWEST
FLOW BRINGS ANOTHER MOIST STORM SYSTEM INTO THE AREA FOR THE MIDDLE
TO LATTER PORTION OF THE WEEK
SHORT TERM (THROUGH 12Z TUESDAY)
A LONGWAVE TROUGH REMAINS IN
PLACE ACROSS THE WESTERN CONUS THIS MORNING, WITH A CLOSED LOW OVER
SOUTHEAST IDAHO. THIS LONGWAVE TROUGH WILL MAINTAIN AN UNSEASONABLY
COLD AIRMASS OVER THE AREA TODAY AND TOMORROW. A SHORTWAVE
DISTURBANCE EMBEDDED WITHIN THE LONGWAVE TROUGH AND WHICH IS
CURRENTLY DIVING IN ACROSS THE PACNW STATES AND NORCAL WILL ARRIVE
INTO UTAH LATE THIS AFTERNOON. AHEAD OF THIS FEATURE, A REINFORCING
COLD FRONT WILL PUSH INTO UTAH, RELATIVELY WEAK ACROSS THE NORTH BUT
STRENGTHENING AS IT REACHES SOUTHERN UTAH THIS AFTERNOON. ALREADY
SEEING AN AREA OF SHOWERS MOVING ACROSS NORTHERN UTAH NEAR THIS
BOUNDARY. THE SNOW SHOWERS WILL EXPAND IN COVERAGE ACROSS THE
FORECAST AREA THROUGH THE DAY OWING TO THE BOUNDARY AND INCREASED
INSTABILITY ASSOCIATED WITH DAYTIME HEATING.
THE SNOW SHOWERS WILL DECREASE OVERNIGHT AS THE TROUGH EXITS THE
AREA. HOWEVER, LINGERING MOISTURE AND COLD AIR ALOFT MAY SET OFF
LAKE-EFFECT SNOW ACROSS THE GSL LATE TONIGHT INTO TOMORROW MORNING.
LOCAL EXPERIMENTAL GUIDANCE BASED ON THE 00Z GFS INDICATE A 50-65%
CHANCE OF LAKE-EFFECT SNOW DURING THIS TIMEFRAME. EARLIER RUNS OF HI-
RES MODELS WERE ALSO PRODUCING A SOLID LAKE BAND. HOWEVER, SOME OF
THEM HAVE NOW PULLED BACK WITH THE LATEST RUNS, WHICH SUGGESTS THAT
THE PROBABILITY COULD BE LOWER THAN THE AFOREMENTIONED EXPERIMENTAL
GUIDANCE. HOWEVER, IF THE LAKE EFFECT OCCURS, THE MOST LIKELY AREA
OF IMPACT WILL BE THE SL VALLEY INTO THE COTTONWOOD CANYONS,
ALTHOUGH SOUTHERN DAVIS COUNTY AND THE EASTERN TOOELE VALLEY AND
OQUIRRHS COULD BE IMPACTED AT TIMES AS WELL. AT THIS TIME, SNOW
SHOWERS TODAY AND TONIGHT ARE EXPECTED TO BE BELOW ADVISORY
CRITERIA, WITH MINOR VALLEY ACCUMULATIONS AND 2-6 INCHES IN THE
MOUNTAINS. HOWEVER, IF LAKE-EFFECT SNOW DOES OCCUR, AREAS UNDERNEATH
SAID LAKE EFFECT COULD SEE LOCALIZED HEAVIER SNOW WHICH COULD
WARRANT A WINTER WEATHER HIGHLIGHT AND BRING IMPACTS TO THE MORNING
COMMUTE. GIVEN TYPICAL UNCERTAINTY REGARDING LAKE EFFECT EVENTS,
WILL ALLOW FUTURE SHIFTS TO EVALUATE THE FORECAST FURTHER AND TO
ALLOW COORDINATION WITH CORE PARTNERS.
MUCH QUIETER WEATHER IS EXPECTED TOMORROW AFTERNOON THROUGH TOMORROW
NIGHT AS A SHORTWAVE RIDGE BUILDS INTO THE AREA. TEMPERATURES ARE
FORECAST TO WARM A FEW DEGREES FOR TOMORROW, BUT REMAIN 15-25F BELOW
CLIMATOLOGICAL NORMALS. STILL, AT LEAST IT IS STARTING TO TREND IN
THE RIGHT DIRECTION. BUT IS IT FINALLY THE END OF THE ACTIVE WEATHER
PATTERN OF LATE? NOPE.
LONG TERM (AFTER 12Z TUESDAY)
ACTIVE PATTERN CONTINUES THROUGH
THE FORESEEABLE FUTURE, WITH ONLY BRIEF TRANSITORY RIDGING
INTERRUPTING OTHERWISE PERSISTENT LONGWAVE TROUGHS PARKED OVER THE
GREAT BASIN THROUGH DAY 7 AND BEYOND. COOLER AND WETTER THAN AVERAGE
CONDITIONS WILL PERSIST FOR NORTHERN AND CENTRAL UTAH, WHILE
SOUTHERN UTAH MAY EXPERIENCE SLIGHTLY MORE EFFECTIVE WARMING WITH
BETTER EXPOSURE TO WARM ADVECTION IN BRIEF RIDGING AND BETTER
CHANCES FOR CLEARING SKIES BETWEEN STORMS.
FORECAST REMAINS LARGELY UNCHANGED FROM PRIOR FORECAST CYCLES WITH
ONLY MINOR CHANGES TO TIMING AS ENSEMBLE MEAN SLOWS THE PROGRESSION
OF THE TROUGH THROUGH THE REGION. ONSET TIMING REMAINS MID-MORNING
WEDNESDAY AS MOISTURE PUSHES IN FROM THE SOUTHWEST ALONG THE LEADING
EDGE OF THE POSITIVELY TILTED TROUGH, WITH BROAD SYNOPTIC LIFT UNDER
A FAVORABLY LOCATED JET MAX KICKING OFF PRECIPITATION FROM
SOUTHWESTERN UTAH TO SOUTHWESTERN WYOMING NEARLY SIMULTANEOUSLY.
CONTINUED PRECIPITATION IS FORECAST THROUGH THURSDAY, THOUGH WILL
BECOME MORE SHOWERY AS TIME GOES ON AND EVENTUALLY CURTAILED TO
NORTHERN UTAH BY THURSDAY EVENING/FRIDAY MORNING WHERE A MIX OF
OROGRAPHICALLY FORCED PRECIPITATION AND AN EMBEDDED SHORTWAVE
PROVIDE ADDITIONAL FORCING.
WINDS WORTH KEEPING AN EYE ON FOR WESTERN UTAH ON WEDNESDAY,
SOUTHEASTERN UTAH ON THURSDAY, THOUGH REMAIN BELOW IMPACT THRESHOLDS
AT THIS TIME. UNIMPRESSIVE UPPER LEVEL FLOW MAXING OUT NEAR 40KT AT
700MB SHOULD LIMIT WHAT MOMENTUM CAN AND DOES MIX TO THE SURFACE.
INTO THE WEEKEND, THE AFOREMENTIONED TRANSITORY RIDING REMAINS THE
MOST LIKELY SOLUTION, HOWEVER MORE ZONAL PRESENTATIONS AMONG
ENSEMBLE FORECASTS WOULD LEAD TO CONTINUED UNSETTLED BUT UNIMPACTFUL
WEATHER. THE NEXT SYSTEM COULD ARRIVE AS EARLY AS SUNDAY NIGHT.
AVIATION...KSLC
BAND OF SNOW MOVING THROUGH THE SLC METRO THIS
MORNING IS PRODUCING LIFR CONDITIONS, AND 1 TO 3 INCH PER HOUR
SNOWFALL RATES. THIS IS EXPECTED TO PERSIST THROUGH 16Z.
UNSETTLED WEATHER THROUGHOUT THE DAY HAS THE POTENTIAL TO LEAD TO
SOMETIMES BRIEF CHAOTIC WIND SHIFTS AND BRIEF PERIODS OF SNOW IN
THE AFTERNOON. AS SCATTERED SHOWERS CLEAR OUT SUNDAY EVENING, A
LAKE EFFECT SNOW BAND MAY DEVELOP. HOWEVER, SHOULD THIS BAND SHIFT
OVERHEAD, IT HAS THE POTENTIAL TO PRODUCE MODERATE SNOWFALL
BETWEEN 3-7AM LOCAL TIME MONDAY MORNING.
REST OF UTAH AND SOUTHWEST WYOMING
UNSETTLED WEATHER AREA-WIDE
TODAY WILL PRODUCE VARIABLE WINDS WITH LARGELY MVFR CONDITIONS
ACROSS THE NORTH AND VFR CONDITIONS ACROSS CENTRAL AND SOUTHERN
TERMINALS. SCATTERED SHOWERS MAY PRODUCE MODERATE SNOWFALL AND
PERIODS OF IFR WHEN OVERHEAD, ESPECIALLY FOR NORTHERN UTAH AND
SOUTHWEST WYOMING. SHOWERS WILL TAPER OFF THROUGH THE EARLY EVENING
EXCEPT ACROSS FAR NORTHERN UTAH AND SOUTHWEST WYOMING WHERE ACTIVITY
IS LIKELY TO CONTINUE WELL INTO SUNDAY NIGHT.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
ADESMET/CHENG/WESSLER
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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