711
FXUS65 KSLC 310446
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1046 PM MDT SUN AUG 30 2026
KEY MESSAGES
- A MODERATE RISK (LEVEL 3/4) FOR EXCESSIVE RAINFALL IS IN EFFECT ACROSS
PORTIONS OF EASTERN AND SOUTHERN UTAH MONDAY.
- A FLOOD WATCH FOR FLASH FLOODING REMAINS IN EFFECT ACROSS MUCH
OF CENTRAL AND SOUTHERN UTAH THROUGH MONDAY EVENING. THE THREAT
OF FLOODING IS HIGHEST ACROSS SLOT CANYONS, NORMALLY DRY WASHES,
SLICK ROCK AREAS, RECENT BURN SCARS AS WELL AS AREAS THAT HAVE
ALREADY RECEIVED VERY HEAVY RAINFALL THIS WEEKEND INCLUDING THE
SANPETE AND SEVIER VALLEYS, CASTLE COUNTRY, AND THE SAN RAFAEL
SWELL.
- THERE IS AN INCREASING PROBABILITY THAT DEEP MOISTURE ASSOCIATED
WITH A TROPICAL CYCLONE IN THE EASTERN PACIFIC WILL SPREAD
NORTHWARD INTO UTAH AHEAD OF A PACIFIC DISTURBANCE FRIDAY INTO
NEXT WEEKEND.
DISCUSSION
CONVECTION HAS LARGELY WANED LATE THIS EVENING
ACROSS THE AREA, WITH MOST OF UTAH AND SOUTHWEST WYOMING SEEING
SOME RELIEF FROM THE RAINFALL DURING THE OVERNIGHT HOURS. FAR
SOUTHEASTERN UTAH, LARGELY NEAR LAKE POWELL, MAY STILL SEE SOME
SHOWER AND ISOLATED THUNDERSTORM DEVELOPMENT TONIGHT AND
DURING THE MORNING HOURS AS A WEAK SHORTWAVE TROUGH PASSES ACROSS
THE FOUR CORNERS. UNCERTAINTY STILL REMAINS WITH THE TIMING OF
THIS WAVE, WHICH WILL ULTIMATELY DETERMINE THE COVERAGE/INTENSITY
OF AFTERNOON CONVECTION ACROSS FAR SOUTHEASTERN UTAH. EARLIER
MODEL RUNS SUGGESTED SHOWERS MOVING INTO THE AREA BY 9AM WHICH
WOULD LIKELY RESULT IN MORE LIMITED AFTERNOON INSTABILITY.
HOWEVER, RECENT MODEL TRENDS SHOW THIS A BIT LATER, COINCIDENT
WITH DAYTIME HEATING/INSTABILITY.
ACROSS THE REST OF THE AREA, WIDESPREAD THUNDERSTORMS WILL DEVELOP
DURING THE AFTERNOON, OWING TO ANOMALOUS MOISTURE IN PLACE
COUPLED WITH BROAD-SCALE DYNAMICS. THE AFOREMENTIONED SHORTWAVE
TROUGH MOVING THROUGH THE FOUR CORNERS WILL MOVE IN SYNC WITH A
SEPARATE SHORTWAVE TROUGH CROSSING WESTERN UTAH FROM SOUTHWEST TO
NORTHEAST, PROVIDING PLENTY OF LIFT AND DEEP LAYER SHEAR,
ESPECIALLY WHEN CONSIDERING UPPER-LEVEL DIFFLUENCE ALREADY IN
PLACE. THUNDERSTORMS WILL FORM AS THIS SHORTWAVE LIFTS, FIRST
ENTERING THE ST. GEORGE VICINITY LATE MORNING AND BECOMING
WIDESPREAD BY MID-AFTERNOON AS INSTABILITY PEAKS.
WHILE OUTFLOW WINDS ARE ALSO POSSIBLE ALONG THE LEADING EDGE OF
THESE STORMS (ESPECIALLY OVER WEST-CENTRAL AND NORTHWEST UTAH),
THE ENVIRONMENT WILL BE VERY FAVORABLE FOR FLASH FLOODING,
NOTABLY ACROSS SOUTHERN AND EASTERN UTAH AND OVER SENSITIVE AREAS
SUCH AS SLOT CANYONS AND NEAR RECENT BURN SCARS. THIS FLASH FLOOD
THREAT IS ESPECIALLY HIGH GIVEN RECENT RAINFALL ACROSS MUCH OF THE
STATE. HIGH-RES GUIDANCE SUGGESTS STORMS WILL BE CAPABLE OF
PRODUCING RAINFALL RATES POTENTIALLY IN EXCESS OF 1-2"/HR, WITH
AVERAGE RETURN INTERVALS (ARIS) EXCEEDING 10-20 YEARS ACROSS MUCH
OF EASTERN AND SOUTHERN UTAH...LOCALLY HIGHER IN PLACES.
CONDITIONS TREND MUCH DRIER AFTER MONDAY, AND EVEN DRIER FOLLOWING
THE PASSAGE OF ANOTHER SHORTWAVE TROUGH MID-WEEK. HOWEVER, THIS
BREAK MAY BE SHORT-LIVED. MODEL GUIDANCE SUGGEST MOISTURE OF
TROPICAL ORIGINS RETURNS BY THE WEEKEND, COUPLED WITH ANOTHER
DISTURBANCE FROM THE PACNW. PLENTY OF UNCERTAINTY STILL REMAINS,
BUT THIS COULD YET AGAIN INCREASE THE FLASH FLOOD THREAT HEADING
INTO NEXT WEEKEND.
AVIATION
KSLC...THERE IS AROUND A 40% CHANCE OF LIGHT NORTH TO VARIABLE WINDS
FOR A PERIOD OVERNIGHT. SOUTHERLY WINDS LIKELY TO INCREASE BY MID
MORNING MONDAY. MONDAY AFTERNOON WILL SEE CONVECTION CHANCES
INCREASE THROUGH THE AFTERNOON, ESPECIALLY AFTER AROUND 21Z TO 04Z
TUESDAY. STORMS WILL BE CAPABLE OF BRIEF PERIODS OF HEAVY RAIN,
LIGHTNING, AND GUSTY ERRATIC OUTFLOW WINDS. ADDITIONALLY, STRONGER
STORMS WILL BE CAPABLE OF BRIEF CATEGORICAL VIS REDUCTIONS TO MVFR
OR SO, AS WELL AS LOWERED CIGS.
REST OF UTAH AND SOUTHWEST WYOMING...ISOLATED SHOWERS AND
THUNDERSTORMS WILL BE POSSIBLE OVERNIGHT, ESPECIALLY ACROSS CENTRAL
UTAH. WINDS WILL GENERALLY FAVOR A DIURNALLY NORMAL DIRECTION. ON
SUNDAY, SOUTHERLY FLOW WILL INCREASE AS WILL CLOUD COVER. AFTERNOON
SHOWERS AND THUNDERSTORMS WILL ONCE AGAIN BECOME MORE WIDESPREAD
THROUGH THE AFTERNOON HOURS, ESPECIALLY ALONG AND EAST OF UTAH'S
HIGH TERRAIN. LIKE PREVIOUS DAYS, THESE STORMS WILL BE CAPABLE OF
PERIODS OF HEAVY RAIN, LIGHTNING, GUSTY ERRATIC OUTFLOW WINDS, AND
SMALL HAIL. ADDITIONALLY, THE STRONGER STORMS WILL BE CAPABLE OF
PERIODS OF DECREASED VIS TO AROUND MFVR OR SO, AS WELL AS SOME
LOWERED CIGS. IN GENERAL, COVERAGE OF SHOWERS AND THUNDERSTORMS WILL
BEGIN TO WANE LATE EVENING INTO THE OVERNIGHT HOURS.
FIRE WEATHER, ISSUED 208 PM MDT SUN AUG 30 2026
AN ONGOING MONSOON SURGE WILL CONTINUE TO BRING
THE THREAT OF THUNDERSTORMS WITH STRONG WINDS, HAIL AND VERY HEAVY
RAIN TODAY. A FURTHER INCREASE IN MOISTURE WILL BRING AN EVEN
HIGHER THREAT OF HEAVY RAIN MONDAY, ESPECIALLY ACROSS SOUTHERN AND
EASTERN UTAH.
A DRYING TREND WILL BEGIN TUESDAY, WITH HUMIDITIES FALLING TO
NEAR CRITICAL LEVELS ACROSS WESTERN UTAH BY WEDNESDAY. FRIDAY INTO
THE WEEKEND, MOISTURE WILL AGAIN SHIFT INTO THE REGION WITH
INCREASING HUMIDITIES AND THE THREAT OF HEAVY RAINFALL ONCE AGAIN.
SLC WATCHES/WARNINGS/ADVISORIES
UT...FLOOD WATCH THROUGH MONDAY EVENING FOR UTZ116>121-123>131.
WY...NONE.
PUBLIC...CUNNINGHAM
AVIATION...WARTHEN
FIRE WEATHER...KRUSE
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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