040
FXUS65 KSLC 222117
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
317 PM MDT FRI AUG 22 2025
SYNOPSIS
WITH HIGH PRESSURE CENTERED OVER THE FOUR CORNERS,
MONSOON MOISTURE WILL GRADUALLY SPREAD NORTHWARD INTO UTAH AND
SOUTHWEST WYOMING THROUGH EARLY NEXT WEEK. THIS WILL BRING
INCREASED COVERAGE OF SHOWERS AND THUNDERSTORMS, THE POTENTIAL FOR
FLASH FLOODING, AND GRADUALLY LESS HOT TEMPERATURES.
SHORT TERM (THROUGH 12Z/6AM SUNDAY)
AS HIGH PRESSURE CONTINUES
TO NUDGE WESTWARD, MOISTURE IS INCREASING STATEWIDE WITHIN OVERALL
SOUTHERLY FLOW, WITH PWATS REACHING AROUND 0.8-1.1" THIS
AFTERNOON. SCATTERED SHOWERS AND THUNDERSTORMS HAVE DEVELOPED
MAINLY OVER HIGHER TERRAIN, WITH ONLY ISOLATED OUTFLOW WINDS UP
TO 45 MPH OBSERVED; INSTEAD, WE HAVE TRANSITIONED MORE TOWARDS A
FLASH FLOOD REGIME, PERHAPS MORESO THAN HIGH-RES GUIDANCE
INITIALLY SUGGESTED.
MOISTURE WILL FURTHER INCREASE ACROSS THE AREA HEADING INTO
TOMORROW, WITH A SECONDARY MOISTURE PUSH ARRIVING LATE SATURDAY
INTO SUNDAY. THUS, TOMORROW LOOKS TO BE SIMILAR TO TODAY, ALBEIT
WITH A SLIGHTLY HIGHER FLASH FLOOD THREAT AND LOWER DRY MICROBURST
THREAT. WHILE MODEL SOUNDINGS STILL SHOW A SHALLOWER DRY LAYER AT
THE SURFACE BOTH TODAY AND TOMORROW AFTERNOONS, SLOW STORM
MOTIONS, MODEST INSTABILITY, AND ABOVE-NORMAL PWATS WILL COMBINE
FOR THIS INCREASED THREAT OF LOCALIZED FLASH FLOODING,
PARTICULARLY FOR PRONE AREAS LIKE SLOT CANYONS OR AREAS NEAR
RECENT BURN SCARS.
LONG TERM (AFTER 12Z/6AM SUNDAY), ISSUED 522 AM MDT
MONSOONAL MOISTURE IS EXPECTED TO BECOME ESPECIALLY PRONOUNCED
ACROSS THE ENTIRETY OF UTAH AND SOUTHWEST WYOMING ON SUNDAY INTO
EARLY NEXT WEEK, WITH PWAT ANOMALIES PUSHING 150-200% OF NORMAL
AREAWIDE. AS SUCH, EXPECT WIDESPREAD COVERAGE OF SHOWERS AND
THUNDERSTORMS EACH DAY, WITH THIS AMOUNT OF MOISTURE IN THE COLUMN
FAVORABLE FOR LOCALLY HEAVY RAINFALL UNDER STRONGER CORES. THE
WEATHER PREDICTION CENTER CONTINUES TO CARRY A MARGINAL RISK
(LEVEL 1 OF 4) FOR EXCESSIVE RAINFALL ACROSS THE ENTIRE FORECAST
AREA THROUGH AT LEAST TUESDAY. THOSE WITH OUTDOOR PLANS SHOULD
CONTINUE TO MONITOR THE FORECAST GIVEN THE ASSOCIATED RISK FOR
FLASH FLOODING. LOCATIONS WITH GREATEST THREATS FOR FLASH FLOODING
INCLUDE SLOT CANYONS, NORMALLY DRY WASHES, SLICKROCK AREAS,
RECENT BURN SCARS, AND URBAN AREAS.
WHILE MOISTURE AVAILABILITY WILL BE PLENTIFUL, THE ONE FACTOR THAT
COULD IMPACT AFTERNOON CONVECTIVE DEVELOPMENT AND EVOLUTION INCLUDES
THE POTENTIAL FOR NOCTURNAL CONVECTION. IF ANY NOCTURNAL CONVECTION
OCCURS AND SKIES REMAIN SUFFICIENTLY CLOUDY, WE COULD SEE MORE
STABLE ATMOSPHERIC CONDITIONS DEVELOP. THIS WOULD INHIBIT THE
DEVELOPMENT OF CONVECTION INTO THE AFTERNOON, INSTEAD FAVORING A
MORE STRATIFORM PRECIP REGIME. WILL BE SOMETHING TO MONITOR AS WE
GET CLOSER.
IN ADDITION TO WIDESPREAD PRECIPITATION, THIS PATTERN WILL BRING A
MUCH-NEEDED GRADUAL COOLING TREND THROUGHOUT THE LONG TERM PERIOD.
TEMPERATURES BEGIN NEAR-AVERAGE ON SUNDAY, DROPPING TO AROUND 5-10F
BELOW SEASONAL AVERAGES BY THE END OF THE WEEK.
AVIATION...KSLC
MOISTURE TO CONTINUE TO INCREASE, CORRESPONDING
TO INCREASE IN SHOWER/THUNDERSTORM CHANCES, PRIMARILY FROM EARLY
AFTERNOON TO EVENING. CONVECTION WILL BE CAPABLE OF BRIEF PERIODS OF
MODERATE TO HEAVY RAIN, LIGHTNING, GUSTY ERRATIC OUTFLOW WINDS, AND
BRIEFLY REDUCED VIS/CIGS. ASIDE FROM PRECIPITATION, WINDS
ANTICIPATED TO FOLLOW A TYPICAL DIURNAL PATTERN (SHIFTING SSE ~03-
05Z SAT, BACK NW 17-19Z THEREAFTER).
REST OF UTAH AND SOUTHWEST WYOMING
A MONSOONAL MOISTURE SURGE
WILL RESULT IN A MORE ACTIVE PERIOD, ESPECIALLY AT SOUTHERN UTAH
TERMINALS. SHOWER/THUNDERSTORM CHANCES WILL BE MAXIMIZED EARLY
AFTERNOON THROUGH THE EVENING, AND BRING A THREAT OF MODERATE TO
HEAVY RAIN, LIGHTNING, GUSTY ERRATIC OUTFLOW WINDS, AND BRIEFLY
REDUCED VIS/CIGS. OUTSIDE PRECIPITATION, WINDS ARE EXPECTED TO
FOLLOW A LARGELY TYPICAL DIURNAL PATTERN WITH MAGNITUDES REMAINING
MODEST.
FIRE WEATHER
MOISTURE WILL CONTINUE TO MOVE INTO UTAH FROM THE
SOUTH, WITH ANOTHER SECONDARY SURGE ARRIVING SUNDAY. COVERAGE OF
SHOWERS AND THUNDERSTORMS WILL CONTINUE TO INCREASE. STORMS WILL
BECOME WETTER, WITH INCREASING CHANCES FOR WETTING RAIN AND
DECREASING CHANCES FOR GUSTY OUTFLOW WINDS THROUGH AT LEAST
WEDNESDAY. RELATIVE HUMIDITY WILL ALSO IMPROVE ACCORDINGLY. ONE
AREA OF FORECAST UNCERTAINTY IS THE AMOUNT OF CLOUD COVER, WHICH
MAY LIMIT THE INTENSITY OF ANY DEVELOPING STORMS AND THEREFORE
RAINFALL AMOUNTS, PARTICULARLY AFTER SUNDAY. MODEL GUIDANCE
CURRENTLY SUGGESTS MOISTURE WILL PEAK AROUND WEDNESDAY, WITH A
GRADUAL DECREASE IN MOISTURE THEREAFTER.
SLC WATCHES/WARNINGS/ADVISORIES
UT...EXTREME HEAT WARNING UNTIL 9 PM MDT THIS EVENING FOR UTZ123-124.
WY...NONE.
CUNNINGHAM/WHITLAM/WARTHEN
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