678
FXUS65 KSLC 171216
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
616 AM MDT THU SEP 17 2026
KEY MESSAGES, ISSUED 1253 PM MDT WED SEP 16 2026
- FLASH FLOODING REMAINS THE PRIMARY WEATHER RISK ACROSS SOUTHERN
AND EASTERN UTAH THROUGH FRIDAY. MULTIPLE ROUNDS OF SHOWERS AND
THUNDERSTORMS WILL BRING THE THREAT FOR LOCALLY HEAVY RAINFALL.
- A FLOOD WATCH FOR FLASH FLOODING HAS BEEN ISSUED FROM LATE
TONIGHT THROUGH THURSDAY MORNING FOR MUCH OF SOUTHERN UTAH,
WHILE THE WATCH EXTENDS THROUGH THURSDAY EVENING FOR MUCH OF
CARBON AND EMERY COUNTIES.
- A MARGINAL RISK FOR SEVERE THUNDERSTORMS (LEVEL 1/5) CONTINUES
FOR WEDNESDAY MORNING INTO WEDNESDAY AFTERNOON ACROSS PORTIONS
OF NORTHERN UTAH.
DISCUSSION, ISSUED 1253 PM MDT WED SEP 16 2026
THE MAIN WEATHER THREAT WILL CONTINUE TO BE FLASH FLOODING,
ESPECIALLY ACROSS SOUTHERN AND EASTERN UTAH. A SLOW MOVING UPPER
LOW OVER NORTHERN CALIFORNIA NORTHWEST NEVADA WITH A BROAD RIDGE
TO OUR EAST IS HELPING TO DIRECT MONSOON MOISTURE NORTHWARD ACROSS
UTAH. WHILE ISOLATED TO WIDELY SCATTERED SHOWERS AND THUNDERSTORMS
WILL CONTINUE TO DEVELOP ACROSS MUCH OF THE AREA THIS AFTERNOON,
THE STRONGEST STORMS WITH THE BEST THREAT OF FLASH FLOODING WILL
BE ACROSS SOUTHERN AND EASTERN UTAH WHERE THE DEEPEST MOISTURE
AND CAPE VALUES TO AROUND 1000 J/KG WILL BE IN PLACE THIS
AFTERNOON. FORCING WILL CONTINUE INCREASE ACROSS SOUTHEASTERN UTAH
BY LATER THIS AFTERNOON INTO THIS EVENING AS A SHORTWAVE EMBEDDED
IN THE SOUTHERLY FLOW EVOLVES NORTHWARD OUT OF ARIZONA.
AS THIS WAVE PUSHES INTO EASTERN UTAH THIS EVENING, THE MOISTURE
AND FORCING WILL SPREAD IN FARTHER TO THE WEST INTO SOUTHWEST
UTAH AS WELL WITH THE DEEP SOUTHERLY MOISTURE FLOW FAVORING STORMS
DEVELOPING IN UPSLOPE PRONE AREAS FROM THE SOUTH, SUCH AS THE
PINE VALLEY MOUNTAINS (FORSYTH BURN SCAR), AS WELL AS ACROSS THE
GRAND STAIRCASE EAST TO BOULDER SUMMIT. IN ADDITION, THE
CONVERGENCE INTO THE TERRAIN AROUND CASTLE COUNTY, PRICE, AND
OVER THE TAVAPUTS WILL ALSO FAVOR CONTINUED THUNDERSTORM
DEVELOPMENT AND TRAINING. OF CONCERN IN SOUTHWEST UTAH, INCLUDING
THE PINE VALLEYS AND ST GEORGE AREA, IS THAT HEAVY RAINFALL WILL
TIMED OVERNIGHT, MAINLY BETWEEN 9 PM MDT AND THE EARLY MORNING
HOURS ON THURSDAY. MEANWHILE, ACROSS EASTERN UTAH OVERNIGHT, AS
THE MAIN SHORTWAVE MOVES THROUGH AN AREA OF BROAD LIGHT TO
MODERATE RAINFALL IS EXPECTED, WHICH WILL HELP TO FURTHER SATURATE
THE SOILS AND ADD WATER INTO AREA WATERWAYS. THIS MAY BECOME A
FACTOR INTO THURSDAY FOR MAINLY EMERY AND CARBON COUNTIES WHERE
THERE WILL BE THE HIGHEST POTENTIAL FOR THUNDERSTORMS DEVELOPING
LATER THURSDAY AFTERNOON THROUGH THURSDAY EVENING OFF OF THE
CENTRAL MOUNTAINS AND MOVING INTO AN ENVIRONMENT WITH 30-35 KNOTS
OF SHEAR AND 500-1000J/KG OF CAPE. TRAINING STRONGER
THUNDERSTORMS AND EVEN A SUPERCELL CANNOT BE RULED OUT THERE INTO
THURSDAY EVENING, AND WHEN COMBINED WITH ANY RAIN RECEIVED TODAY
AND TONIGHT, THIS MAY MORE EASILY POSE A FLOOD RISK.
THE POTENTIAL FOR FLASH FLOODING WILL CONTINUE ACROSS SOUTHERN AND
EASTERN UTAH THROUGH FRIDAY AS THE UPPER LEVEL LOW REMAINS TO OUR
WEST ALLOWING THE MONSOON MOISTURE TO REMAIN IN PLACE. FINALLY BY
SATURDAY, MODELS ARE IN GOOD AGREEMENT THAT THE THROUGH WILL
FINALLY PASS UTAH BRINING NORTHWESTERLY WINDS USHERING IN COOL
TEMPERATURES AND DRIER AIR. HOWEVER, THIS DRYING OUT TREND WILL BE
SHORT-LIVED AS ENSEMBLES ARE IN GOOD AGREEMENT THAT A CUTOFF LOW
WILL PARK NEAR LAS VEGAS, ALLOWING FOR A RETURN TO SOUTHERLY FLOW
ACROSS SOUTHERN UTAH WHICH WILL BRING MOISTURE BACK NORTHWARD
AGAIN ALLOWING FOR DAILY SHOWER AND THUNDERSTORMS CHANCES TO
RETURN AGAIN NEXT WEEK.
AVIATION
KSLC...VFR CONDITIONS WILL PERSIST FOR THE KSLC TERMINAL THROUGH THE
PERIOD. SCATTERED SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE ACROSS
THE TERMINAL (~25% CHANCE) THROUGH THE EARLY MORNING HOURS WITH A
LULL MIDDAY BEFORE ISOLATED THUNDERSTORMS DEVELOP THIS AFTERNOON
(30% CHANCE). WINDS WILL STAY OUT OF THE SOUTH THROUGH THE DAY WITH
GUSTY AND ERRATIC WINDS NEAR ANY CONVECTION.
REST OF UTAH AND SOUTHWEST WYOMING...VFR CONDITIONS WILL PERSIST FOR
THE ENTIRE AIRSPACE THROUGH THE PERIOD. CONVECTION WILL SHIFT INTO
THE NORTHERN AIRSPACE THIS MORNING AND RE-DEVELOP LATER THIS
AFTERNOON ACROSS THE NORTHERN AND EASTERN PORTIONS OF THE AIRSPACE.
WINDS WILL MOSTLY BE SOUTHERLY AREAWIDE WITH GUSTY AND ERRATIC WINDS
NEAR CONVECTION.
FIRE WEATHER, ISSUED 314 AM MDT THU SEP 17 2026
SCATTERED SHOWERS AND THUNDERSTORMS WILL REMAIN ACROSS
THE REGION UNTIL A COLD FRONT ARRIVES ON SATURDAY THAT WILL BRING
COOLER AND DRIER AIR ALONG WITH REDUCED WIND SPEEDS. THESE
SHOWERS AND STORMS WILL SHIFT FURTHER NORTH OVER THE NEXT COUPLE
OF DAYS WITH MORE OF A LULL IN ACTIVITY ACROSS SOUTHWESTERN UTAH
(AFTER TONIGHT'S ACTIVITY WINDS DOWN). A BRIEF PERIOD OF DRY
CONDITIONS WITH SEASONAL TEMPERATURES WILL GIVE WAY TO MORE
SHOWERY ACTIVITY ACROSS PORTIONS OF CENTRAL AND SOUTHERN UTAH LATE
MONDAY INTO TUESDAY AS AN AREA OF LOW PRESSURE MOVES INTO THE
GREAT BASIN.
SLC WATCHES/WARNINGS/ADVISORIES
UT...FLOOD WATCH THROUGH THIS EVENING FOR UTZ113-117-120-121.
WY...NONE.
PUBLIC...CHURCH/SEAMAN
AVIATION...MAHAN
FIRE WEATHER...MAHAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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