322
FXUS65 KSLC 211725
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1025 AM MST THU FEB 21 2019
SYNOPSIS
A POTENT WINTER STORM WILL IMPACT MUCH OF SOUTHERN AND CENTRAL
UTAH THROUGH EARLY FRIDAY. HIGH PRESSURE ALOFT WILL FOLLOW THIS
STORM AND BRING DRIER CONDITIONS TO MUCH OF THE AREA ON SATURDAY.
SHORT TERM (THROUGH 00Z MONDAY)
A BROAD LOW PRESSURE SYSTEM WITH ITS CENTER OVER WESTERN NEVADA
THIS MORNING WILL SLOWLY SAG SOUTH TODAY, THEN SHIFT EAST THROUGH
LAKE MEAD TONIGHT BEFORE IT OPENS UP AND CONTINUES TO TRACK ACROSS
THE AREA ON FRIDAY. CURRENTLY, A LOW- LEVEL CIRCULATION EXISTS
ACROSS SOUTHERN NEVADA. SOUTHERLY THROUGH SOUTHEASTERLY UPSLOPE
FLOW ALOFT ACROSS SOUTHERN UTAH AHEAD OF THIS CIRCULATION COMBINED
WITH WARM ADVECTION AND SYNOPTIC LIFT HAS GENERATED WIDESPREAD
SNOW ACROSS SOUTHERN UTAH. THIS TREND WILL CONTINUE LATE THIS
MORNING, WITH SNOW INCREASING FARTHER NORTH ACROSS EASTERN UTAH
THROUGH TONIGHT. AS THE STORM BEGINS TO EXIT THE AREA TOMORROW,
NORTHERLY FLOW BEHIND THE TROUGH AXIS WILL CONTINUE TO PRODUCE
LINGERING SNOWFALL, WITH THE FOCUS TRANSITIONING MORE TO THE I-15
CORRIDOR THROUGH CENTRAL AND SOUTHWEST UTAH. WINTER WEATHER
HIGHLIGHTS REMAIN IN PLACE, WITH NO CHANGES TO THE EXISTING SUITE
OF WARNINGS AND ADVISORIES AT THIS TIME.
MUCH OF THE WASATCH FRONT WILL BE LEFT OUT OF THE SIGNIFICANT
SNOWFALL DUE TO EASTERLY DOWNSLOPE FLOW, ALTHOUGH MINOR
ACCUMULATIONS ARE NOT OUT OF THE QUESTION, ESPECIALLY SOUTHERN UTAH
COUNTY, WESTERN SALT LAKE COUNTY, AND THE TOOELE VALLEY AREA.
SPEAKING OF EASTERLIES, THE MSLP GRADIENT HAS TIGHTENED THROUGH THE
MORNING, CANYON WINDS HAVE INCREASED ALONG THE WASATCH FRONT OVER
THE PAST COUPLE OF HOURS. WE'VE SEEN A FEW LOCALIZED GUSTS IN THE
40 TO 50 MPH RANGE THIS MORNING, HOWEVER IT LOOKS LIKE WINDS WILL
TAPER OFF A BIT THROUGH THE AFTERNOON WITH THE DIURNAL
DESTABILIZATION. HOWEVER, THERE SHOULD BE A BIT BETTER SUPPORT AT
700MB (20-30KT AT 700MB ACROSS THE TERRAIN) THIS EVENING ALONG
WITH INCREASING STABILITY INTO THE NIGHT. EXPECT TO SEE THE MAXIMA
IN EASTERLY CANYON WINDS TONIGHT, ESPECIALLY BETWEEN 7PM AND 2AM,
BEFORE THE 700 MB WIND SUPPORT WANES.
SNOW WILL WIND DOWN BY TOMORROW EVENING AS THE STORM EXITS THE AREA.
UTAH WILL THEN REMAIN UNDER A NORTHWESTERLY FLOW ALOFT ON SATURDAY,
WITH WARM ADVECTION ACROSS NORTHERN UTAH POSSIBLY GENERATING SOME
SNOW ALONG THE IDAHO BORDER. THE PATTERN THEN BECOMES MORE ZONAL ON
SUNDAY WITH CONTINUED GRADUAL WARMING ALOFT WHILE WEAK DISTURBANCES
RIPPLE THROUGH IDAHO. EXPECT FAR NORTHERN UTAH TO REMAIN SOMEWHAT
UNSETTLED, ALTHOUGH TEMPERATURES WILL TREND WARMER. HOWEVER,
SOUTHERN AND EASTERN UTAH MAY BE A BIT SLOWER TO WARM DUE TO SNOW
COVER.
LONG TERM (AFTER 00Z MONDAY)
GLOBAL SUITE SUPPORTS A PATTERN SHIFT ACROSS THE WESTERN CONUS
FOR THE LONG TERM PERIOD, WITH NEAR ZONAL FLOW DOMINATING THE
LOCAL AREA AS THE JET AND "MORE ACTIVE" WEATHER SHIFTS HIGHER IN
LATITUDE OVER THE NORTHERN ROCKIES REGION. MODELS HAVE BEEN
STRUGGLING OVER THE LAST SEVERAL DAYS RESOLVING THIS, WITH MANY
RUNS A BIT MORE AMPLIFIED AND THUS MORE ACTIVE (ACROSS THE
NORTH)...BUT CONFIDENCE IS BUILDING TOWARDS A MORE TRANQUIL AND
WARMER PERIOD SETTING UP FOR NEXT WEEK. CONTINUE TO HOLD ONTO SOME
POPS ACROSS THE NORTHERN THIRD OF THE AREA TO ACCOUNT FOR
PROGRESSIVE WAVES THAT MAY CLIP THE REGION (PRIMARILY MONDAY
NIGHT), BUT HAVE TRENDED POTENTIAL FOR PRECIP DOWN. LIKELY NOT
ENOUGH YET.
AVIATION
WINDS AT THE SLC TERMINAL ARE EXPECTED TO REMAIN NORTHERLY AS THE
DAY PROGRESSES BUT DUE THE WINDS ALOFT BECOMING STRONGER AND MORE
EASTERLY AFTER 00Z THERE IS A 40% CHANCE THAT WINDS BECOME
SOUTHWEST AT TIMES THIS EVENING. THERE IS A 30% CHANCE THAT CIGS
LOWER BELOW 6KT FT AGL AFTER 06Z.
SLC WATCHES/WARNINGS/ADVISORIES
UT...WINTER STORM WARNING UNTIL 9 AM MST FRIDAY FOR UTZ012-013-016-
019>021.
WIND ADVISORY UNTIL 3 AM MST FRIDAY FOR UTZ001>004.
WINTER WEATHER ADVISORY UNTIL 4 PM MST FRIDAY FOR UTZ010-517.
WINTER STORM WARNING UNTIL 4 PM MST FRIDAY FOR UTZ518.
WINTER WEATHER ADVISORY UNTIL 9 AM MST FRIDAY FOR UTZ011-014-015.
WY...NONE.
SHORT TERM...CHENG/CHURCH
LONG TERM...MERRILL
AVIATION...STRUTHWOLF
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP
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