104
FXUS65 KSLC 160936
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
336 AM MDT TUE SEP 16 2025
SYNOPSIS
A GRAZING STORM SYSTEM WILL MOVE EAST OUT OF THE AREA
TODAY. DRIER CONDITIONS WILL MOVE IN BEHIND IT FOR WEDNESDAY AND
THURSDAY WITH A SLOW TEMPERATURE WARMING TREND. MOISTURE AND
INSTABILITY WILL INCREASE FRIDAY INTO THE WEEKEND.
SHORT TERM (THROUGH 12Z/6AM THURSDAY)
THE GRAZING PACIFIC
NORTHWEST STORM SYSTEM IS MOVING ACROSS NORTHEAST UTAH AND
SOUTHWEST WYOMING THIS MORNING. ASSOCIATED SHOWERS HAVE BEEN
SCATTERED AND GENERALLY WEAK, THOUGH A SMALL CELL DID BRIEFLY
BRING PEA SIZED HAIL TO SLC AIRPORT. AS THE TROUGH CONTINUES EAST
DURING THE DAY, THE COVERAGE OF ASSOCIATED SHOWERS WILL DIMINISH
AND SHIFT EAST. TEMPERATURES WILL STAY ON THE COOL SIDE FOR
NORTHERN PORTIONS OF THE FORECAST AREA BEHIND THE ASSOCIATED
FRONT, UP TO 5F BELOW SEASONAL NORMALS. SOUTHERN UTAH WILL
CONTINUE TO SEE TEMPERATURES NEAR NORMAL FOR THIS TIME OF YEAR.
AS THE SYSTEM MOVES AWAY FROM THE AREA, HIGH PRESSURE WILL AMPLIFY
OVER THE GREAT BASIN, PUTTING UTAH AND SOUTHWEST WYOMING UNDER A
DRY NORTHERLY FLOW ALOFT. THIS WILL SUPPRESS CONVECTION OVER THE
AREA FOR THE MIDDLE PART OF THE WEEK AND BRING A SLOW WARMING
TREND IN TEMPERATURES.
LONG TERM (AFTER 12Z/6AM THURSDAY)
BY THURSDAY, UTAH AND
SOUTHWEST WYOMING REMAIN UNDER HIGH PRESSURE, SANDWICHED IN BETWEEN
THE EXITING LOW TO OUR EAST AND A WEAK CIRCULATION OVER SOUTHERN
CALIFORNIA. THUS, CONDITIONS WILL BE LARGELY QUIET ON THURSDAY, WITH
CLEAR SKIES AND NEAR-NORMAL TEMPERATURES ACROSS MOST OF THE AREA.
BY LATE THURSDAY, HOWEVER, MOISTURE WILL BEGIN TO PUSH INTO THE AREA
FROM THE SOUTHWEST AS THE AFOREMENTIONED CALIFORNIA LOW NUDGES THE
RIDGE AXIS TO OUR EAST. WITH SUBTLE UPPER-LEVEL DIFFLUENCE WITHIN
THIS INCREASING MOISTURE, CHANCES FOR SHOWER AND THUNDERSTORM
DEVELOPMENT WILL INCREASE DURING THE OVERNIGHT HOURS. THERE IS STILL
SOME UNCERTAINTY REGARDING TIMING, THUS THE SPATIAL EXTENT OF THESE
NOCTURNAL SHOWERS IS STILL YET TO BE DETERMINED. THIS MOISTURE WILL
QUICKLY OVERSPREAD THE REST OF THE STATE THROUGH THE DAY ON FRIDAY,
RESULTING IN MORE SCATTERED SHOWERS/THUNDERSTORMS. AS THIS WEAKENING
LOW EJECTS ACROSS NORTHWESTERN UTAH, INCREASED SHEAR COULD PRODUCE
MORE ORGANIZATION WITH THESE STORMS ON FRIDAY/SATURDAY AFTERNOONS.
ENSEMBLE GUIDANCE SUGGESTS MOISTURE PEAKS BY SATURDAY, WITH AN
OVERALL DOWNWARD TREND THEREAFTER AS RELATIVELY ZONAL FLOW BRINGS IN
A DRIER AIR MASS ACROSS AT LEAST NORTHERN/CENTRAL UTAH AND SOUTHWEST
WYOMING. ACROSS SOUTHERN UTAH, THERE IS MUCH LOWER CONFIDENCE IN
WHEN/IF THIS MOISTURE EXITS. CONFIDENCE IS, HOWEVER, INCREASING IN
THE LONGWAVE PATTERN HEADING INTO NEXT WEEK, WITH MODELS LARGELY
CONVENING ON A RIDGE BUILDING ACROSS THE WESTERN US, WITH A CUTOFF
LOW ROTATING NEAR SOUTHERN CALIFORNIA BY DAY 7.
AVIATION...KSLC
NOCTURNAL SHOWERS/THUNDERSTORMS WILL LIKELY END
BY 11Z IF NOT SOONER, WITH CLOUD COVER DISSIPATING AFTER 12Z.
NORTHWESTERLY FLOW WILL PREVAIL THROUGH THE DAY, ALTHOUGH WINDS MAY
BECOME LIGHT AND SOMEWHAT VARIABLE AT TIMES BETWEEN ~11-15Z. VFR
CONDITIONS WILL PERSIST.
REST OF UTAH AND SOUTHWEST WYOMING
NOCTURNAL
SHOWERS/THUNDERSTORMS SITUATED ALONG A WEAK FRONTAL BOUNDARY OVER N-
UT/SW-WY EARLY THIS MORNING (ROUGHLY BETWEEN KTVY-KFBR) WILL
CONTINUE TO SHIFT EASTWARD, LIKELY DISSIPATING BETWEEN ~14-16Z.
ASIDE FROM SCATTERED SHOWERS/THUNDERSTORMS REDEVELOPING OVER THE
UINTA MTNS/UINTA BASIN THIS AFTERNOON, CONDITIONS WILL BE LARGELY
QUIET WITH MOSTLY CLEAR SKIES. WINDS WILL FAVOR A NORTHWESTERLY
DIRECTION THIS AFTERNOON, WITH LIGHT AND TERRAIN-DRIVEN WINDS
RETURNING DURING THE EVENING.
FIRE WEATHER
A MEANDERING STORM SYSTEM WILL CONTINUE TO GRAZE
NORTHEASTERN PORTIONS OF UTAH TODAY, BRINGING ADDITIONAL SCATTERED
SHOWERS AND THUNDERSTORMS THROUGH THE AFTERNOON. NORTHERN UTAH
TEMPERATURES WILL STAY ON THE COOL SIDE, ABOUT 5F BELOW NORMAL FOR
THIS TIME OF YEAR. AS THE SYSTEM EXITS TONIGHT, HIGH PRESSURE WILL
RETURN FOR WEDNESDAY INTO THURSDAY. THIS WILL BRING A STEADY
WARMING AND DRYING TREND. MOISTURE WILL START TO INCREASE OVER
SOUTHERN UTAH FRIDAY AS THE FLOW ALOFT BECOMES SOUTHWESTERLY. A
WEAK STORM SYSTEM MOVING THROUGH THE AREA LATE FRIDAY INTO EARLY
SATURDAY WILL PROVIDE ADDITIONAL MOISTURE AND INSTABILITY, WITH
UNSETTLED CONDITIONS CONTINUING INTO EARLY NEXT WEEK.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
SHORT TERM/FIRE WEATHER...TRAPHAGAN
LONG TERM/AVIATION...CUNNINGHAM
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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