148
FXUS65 KSLC 172241
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
341 PM MST MON FEB 17 2025
SYNOPSIS
MULTIPLE DISTURBANCES WILL RESULT IN PERIODS OF
PRECIPITATION THROUGH TUESDAY, BRINGING ACCUMULATING MOUNTAIN SNOW.
AFTER A BRIEF BREAK, ANOTHER STORM SYSTEM IS EXPECTED TO MOVE
THROUGH THE AREA LATE WEDNESDAY INTO THURSDAY, WITH A DRIER
PATTERN DEVELOPING THEREAFTER.
SHORT TERM (THROUGH 12Z/5AM WEDNESDAY)
ANOTHER DAY IN THE ONGOING
ACTIVE CYCLE AS YET ANOTHER EMBEDDED SHORTWAVE PIVOTS IN. WITH
COLDER LOW TO MID LEVEL TEMPS PUSHING IN BEHIND AN ILL DEFINED
BAROCLINIC ZONE, LOW/MID LEVEL LAPSE RATES HAVE STEEPENED AND
RESULTED IN SOME VERY MODEST DESTABILIZATION ACROSS PORTIONS OF THE
REGION. AS A RESULT, IN ADDITION TO INCREASING COVERAGE OF SHOWER
COVERAGE ACROSS THE NORTHERN HALF OF THE FORECAST REGION, A COUPLE
OF INSTANCES OF INTRACLOUD LIGHTNING HAS BEEN NOTED. GIVEN A FEW
STRONGER UPDRAFTS AND THE COLD AIR IN THE NEAR-SURFACE ENVIRONMENT,
WOULDN'T BE SURPRISED TO SEE A FEW OF THESE CELLS BRING PERIODS OF
GRAUPEL AND/OR SNOW TO LOW ELEVATIONS, ESPECIALLY AS SNOW LEVELS
CONTINUE TO DROP MOVING TOWARDS THE EVENING, OR AT AREAS WHERE
INITIAL SNOW LEVELS ARE ALREADY LOWER (NEARER THE ID BORDER). FOR
HIGHER ELEVATIONS, ANTICIPATE PERIODS OF HIGHER PRECIPITATION RATES
WITH THESE ENHANCED CELLS. TO THAT END, GIVEN THE AFOREMENTIONED
ENVIRONMENT, A NON-ZERO VALUE TO THE SNOW SQUALL PARAMETER IS NOTED,
ESPECIALLY FOR HIGH TERRAIN AND PLACES LIKE SOUTHWEST WYOMING.
TONIGHT INTO TOMORROW THE SHORTWAVE IMPULSE PIVOTS THROUGH OVERHEAD,
WITH DRIER AIR FINALLY STARTING TO SLIDE INTO THE REGION AHEAD OF A
RIDGE TRANSLATING EASTWARD INTO THE GREAT BASIN. STILL, EXPECT
ENOUGH LINGERING MOISTURE AND JET SUPPORT ALOFT TO TRIGGER MORE
ISOLATED SHOWERS THROUGH MUCH OF TUESDAY, WITH STRONG DEEP
NORTHWESTERLY FLOW SUPPORTING CONTINUED NORTHERN MOUNTAIN SNOW UNTIL
LOWER LEVEL MOISTURE FULLY SCOURS OUT. WHILE LOOKING MORE MEAGER
THAN MONDAY, SOME VERY LOW END DESTABILIZATION DOES LOOK LIKE A
POSSIBILITY, AND ONCE AGAIN A NON-ZERO SNOW SQUALL PARAMETER
MATERIALIZES PARTICULARLY FOR THE HIGH TERRAIN AND SOUTHWEST WYOMING.
QUIETER CONDITIONS FINALLY MATERIALIZE MOVING INTO TUESDAY NIGHT AS
THE RIDGE AXIS SHIFTS CLOSER AND FURTHER DRYING OCCURS. WHILE SOME
CLEARING OF CLOUD COVER IS EXPECTED, MORNING LOWS SHOULD WIND UP
SEASONABLY COOL FOR MID TO LATE FEBRUARY.
LONG TERM (AFTER 12Z/5AM WEDNESDAY)
THE LONG TERM PERIOD WILL BE
FOCUSED ON ONE STORM LATE WEDNESDAY THROUGH EARLY FRIDAY. THIS STORM
WILL BRING MOUNTAIN SNOW AND A MIX OF VALLEY RAIN/MOUNTAIN SNOW,
PRIMARILY TO THE NORTHERN HALF OF UTAH AND SW WYOMING. AFTERWARDS, A
DRY AND WARMING TREND WILL ENSUE FOR THE REMAINDER OF THE PERIOD AS
RIDGING BUILDS INTO THE SOUTHWESTERN CONUS.
TRANSIENT RIDGING WILL BE IN PLACE FOR MOST OF THE DAY ON WEDNESDAY
BEFORE A CUTOFF LOW MOVES INTO THE REGION OVERNIGHT. THIS LOW WILL
INITIALLY BE MOVING IN TO THE PNW DURING THE DAY ON WEDNESDAY IN THE
FORM OF A LONGWAVE TROUGH. AS IT MOVES ASHORE IT WILL SPLIT,
ULTIMATELY BECOMING A CLOSED LOW. THIS WILL LIMIT THE MAGNITUDE OF
COLD AIR THAT ACCOMPANIES THE AIRMASS. THE BAROCLINIC ZONE ARRIVES
OVERNIGHT WEDNESDAY INTO EARLY THURSDAY MORNING. MOST OF THE
PRECIPITATION WILL OCCUR ALONG AND BEHIND THE FRONTAL PASSAGE AS THE
AIRMASS AHEAD OF THE FRONT WILL BE RELATIVELY DRY. WITH THE FRONTAL
PASSAGE, MOISTURE WILL BE IN THE FORM OF VALLEY RAIN AND MOUNTAIN
SNOW ALONG WITH SOUTHWEST FLOW TRANSITIONING TO WESTERLY AND THEN
NORTHWESTERLY FLOW. H7 TEMPERATURES WILL BE KEY WITH THIS AIRMASS.
THE 50TH PERCENTILE AMONGST ENSEMBLE MEMBERS HAS H7 TEMPERATURES
GETTING DOWN TO -9C. THIS WILL KEEP SNOWLEVELS VERY CLOSE TO VALLEY
FLOORS. LOOKING AT SOUNDING PROFILES THERE MAY BE ENOUGH OF A
WETBULB AND STEEP ENOUGH LAPSE RATES TO HELP SOME NORTHERN VALLEYS
TRANSITION OVER TO SNOW. ADDITIONALLY, THE COLUMN LOOKS TO BE
SATURATED ALL THE WAY UP THROUGH ~500 MB WHICH BODES WELL FOR
WIDESPREAD PRECIPITATION ACROSS THE NORTHERN HALF OF THE CWA. GIVEN
THAT THIS STORM WILL BE ARRIVING DURING THE OVERNIGHT PERIOD WHEN
SURFACE TEMPERATURES WILL BE AT THEIR DIURNAL MINIMUM, SNOW THAT
DOES FALL IN THE VALLEYS WILL BE ABLE TO ACCUMULATE ON SURFACES IN
TIME FOR THE MORNING COMMUTE. QPF TOTALS FOR THE MOUNTAINS ARE
BETWEEN 0.25"-1.00" (25TH-75TH PERCENTILES), AND FOR THE VALLEYS
IT'S BETWEEN ~0.10"-0.30". THIS WOULD ROUGHLY TRANSLATE TO ABOUT 3-
10" OF SNOW FOR THE MOUNTAINS AND 1-3" OF SNOW FOR VALLEY LOCATIONS
THAT ARE ABLE TO TRANSITION FULLY OVER TO SNOW. SOME GUIDANCE, SUCH
AS THE NAM, ARE VERY BULLISH ON SNOWFALL RATES AND SUGGESTING MORE
SUBSTANTIAL VALLEY TOTALS. THIS WILL BE SOMETHING WORTH WATCHING AS
MORE HIGH-RES GUIDANCE COMES INTO THE MIX.
PRECIPITATION WILL GRADUALLY TRANSITION TO MORE OROGRAPHICS
THROUGHOUT THE DAY ON THURSDAY WITH ALL OF THE MOISTURE ENDING BY
FRIDAY MORNING. BEYOND THIS, A DRIER AND WARMING PATTERN WILL BEGIN
AS RIDGING MOVES INTO THE SOUTHWESTERN CONUS.
AVIATION...KSLC
SCATTERED SHOWERS WILL CONTINUE THROUGH ROUGHLY
06-07Z. RAIN WILL BE THE PRIMARY PRECIPITATION TYPE, THOUGH GRAUPEL
OR RAIN-SNOW MIX MAY DEVELOP WITHIN HEAVIER SHOWERS, PARTICULARLY
LATER IN THE EVENING. VFR CONDITIONS AND MOUNTAIN OBSCURATION WILL
LIKELY PREVAIL, WITH A 30% CHANCE OF MVFR CIGS. NORTHWESTERLY WINDS
WILL PERSIST THROUGH AT LEAST 04Z, THOUGH WINDS MAY BE A BIT ERRATIC
NEAR SHOWERS. WINDS WILL BE FAIRLY LIGHT AND VARIABLE AFTER 08Z.
REST OF UTAH AND SOUTHWEST WYOMING
SCATTERED SHOWERS WILL PERSIST
THROUGH ROUGHLY 06-08Z ACROSS CENTRAL/NORTHERN UT/SOUTHWEST WY,
ROUGHLY NORTH OF I-70, PRODUCING OCCASIONAL MVFR CONDITIONS,
PARTICULARLY FOR HIGHER ELEVATION SITES (KEVW, KHCR). MOST LOWER
ELEVATION SITES WILL SEE A RAIN-SNOW MIX, WITH OTHER SITES (KEVW,
KHCR, EVEN KLGU) TRANSITIONING TO SNOW THIS EVENING IF THEY HAVEN'T
ALREADY. WINDS MAY BE SOMEWHAT ERRATIC NEAR SHOWERS THIS AFTERNOON.
BREEZY WINDS OUT OF THE WEST (ROUGHLY SOUTH OF KMLF-KPUC) WILL
PERSIST THROUGH THE AFTERNOON BEFORE DIMINISHING THIS EVENING.
SLC WATCHES/WARNINGS/ADVISORIES
UT...WINTER WEATHER ADVISORY UNTIL NOON MST TUESDAY FOR UTZ110>112.
WY...NONE.
SHORT TERM...WARTHEN
LONG TERM...MAHAN
AVIATION...CUNNINGHAM
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
CLICK HERE TO GO TO PREVIOUS BULLETINS.
Main Text Page