573
FXUS65 KSLC 230940
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
340 AM MDT SAT AUG 23 2025
SYNOPSIS
HIGH PRESSURE WILL CONTINUE TO DRAW MONSOON MOISTURE
NORTH INTO UTAH AND SOUTHWEST WYOMING THROUGH THE MIDDLE OF THE
UPCOMING 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 MONDAY)
HIGH PRESSURE IS CENTERED
OVER UTAH AND SOUTHWEST WYOMING THIS MORNING, WITH MONSOON
MOISTURE CONTINUING TO SPREAD NORTHWARD INTO THE AREA. SATELLITE
DERIVED PWS INDICATE VALUES PREDOMINATELY IN THE 1.0 TO 1.2 INCH
RANGE ACROSS THE SOUTHERN TWO-THIRDS OF THE AREA, WITH VALUES OF
0.6 TO 0.8 INCH OVER FAR NORTHERN UTAH AND SOUTHWEST WYOMING. A
FEW LIGHT SHOWERS ARE PERSISTING OVERNIGHT OVER CENTRAL AND
SOUTHERN UTAH IN ASSOCIATION WITH SOME WEAK SHORTWAVE ENERGY, AND
WILL TEND TO WEAKEN LATER IN THE MORNING.
IN THIS MOISTURE RICH AIRMASS, WILL SEE ADDITIONAL DEVELOPMENT OF
SHOWERS AND THUNDERSTORMS THIS AFTERNOON WITH THE HEATING OF THE
DAY. THE CONVECTION WILL BE CONCENTRATED IN THE SOUTHERN TWO-
THIRDS OF THE STATE, IN ASSOCIATION WITH THE GREATEST MOISTURE. IN
THE ABSENCE OF ANY LARGE SCALE FORCING MECHANISM, THE STORMS WILL
BEGIN OVER THE HIGHER TERRAIN. DRIFT WILL BE SOMEWHAT LIMITED
GIVEN THE LIGHT FLOW ALOFT UNDER THE LOW, BUT ANY STORMS THAT DO
DRIFT ACROSS SOUTHERN UTAH WILL BE CAPABLE OF HEAVY RAIN THAT
COULD PRODUCE FLASH FLOODING. MOVING NORTHWARD ACROSS THE AREA,
STORMS WITH DRIER LOWER LEVELS WILL BE MORE DOMINANT, BRINGING A
THREAT OF GUSTY MICROBURST WINDS.
BY SUNDAY, THE CENTER OF THE LOW WILL DRIFT BACK TO THE FOUR
CORNERS. WITH SOUTHERLY FLOW INCREASING, MONSOON MOISTURE WILL
CONTINUE INTO THE AREA FROM THE SOUTH IN EARNEST. GUIDANCE
INDICATES PWS IN EXCESS OF 1.0 INCH ACROSS THE VAST MAJORITY OF
THE FORECAST AREA BY THE AFTERNOON, WITH SOME WEAK SHORTWAVES
PROVIDING SOME ADDITIONAL INSTABILITY. THE COMBINATION OF A
SOMEWHAT LESS WARM AIRMASS AND INCREASED CLOUD COVER WILL BRING A
NOTABLE DECREASE IN MAXES ACROSS THE AREA, WITH HIGHS NEAR NORMAL
FOR THIS TIME OF YEAR.
LONG TERM (AFTER 12Z/6AM MONDAY)
THE MID LEVEL RIDGE AXIS WILL
SLOWLY MIGRATE INTO THE SOUTHERN ROCKIES/SOUTHERN PLAINS REGION
DURING THE EARLY PORTION OF THE UPCOMING WEEK. DEEP LAYER SOUTHERLY
FLOW ALONG THE UPSTREAM PERIPHERY OF THIS RIDGE WILL MAINTAIN A
ROBUST MONSOONAL AIRMASS ACROSS THE FORECAST AREA THROUGH AT LEAST
TUESDAY, AND LIKELY THROUGH WEDNESDAY. WIDESPREAD PW VALUES IN
EXCESS OF 1" AND SURFACE DEW POINTS IN THE 50S ACROSS LOW-MID
ELEVATIONS WILL PROVIDE AMPLE MOISTURE FOR SHOWERS AND THUNDERSTORMS
CAPABLE OF PRODUCING HEAVY RAINFALL THROUGH THE FIRST HALF OF THE
WEEK. ULTIMATELY MESOSCALE PROCESSES INCLUDING MCVS WILL DETERMINE
THE DEGREE OF INSTABILITY AND RESULTANT CONVECTIVE COVERAGE MONDAY
THROUGH WEDNESDAY, BUT THE POTENTIAL FOR HEAVY RAINFALL AND
ATTENDANT FLASH FLOODING WILL EXIST ACROSS THE FORECAST AREA DURING
THIS TIMEFRAME.
IT'S WORTH REPEATING THAT THOSE WITH OUTDOOR PLANS, AS WELL AS THOSE
NEAR FLASH FLOOD PRONE AREAS SUCH AS NORMALLY DRY WASHES, RECENT
BURN SCARS, SLICKROCK AREAS AND SLOT CANYONS, SHOULD CONTINUE TO
MONITOR THE FORECAST AND FLASH FLOOD POTENTIAL.
WITH THIS ABUNDANT MOISTURE IN PLACE DAYTIME TEMPERATURES WILL TREND
LOWER THROUGH THE FIRST HALF OF THE WEEK, RUNNING NEAR CLIMO MONDAY
BEFORE FALLING TO 5-8F BELOW CLIMO BY WEDNESDAY.
A MORE WESTERLY FLOW WILL BECOME ESTABLISHED FOR THE LATTER PORTION
OF THE UPCOMING WEEK, WHICH WILL WORK TO GRADUALLY ERODE THE
MONSOONAL AIRMASS. LINGERING MOISTURE WILL MAINTAIN SHOWERS AND
THUNDERSTORMS, HOWEVER COVERAGE WILL DECREASE THURSDAY INTO FRIDAY.
WITH THE DECREASE IN MOISTURE TEMPERATURES ARE FORECAST TO TREND
SLIGHTLY UPWARD HEADING INTO NEXT WEEKEND.
AVIATION...KSLC
VFR CONDITIONS WILL PREVAIL AT KSLC THROUGH THE
TAF PERIOD, WITH SOUTHEAST WINDS SWITCHING TO THE NORTHWEST AROUND
18Z WITH THE LAKE BREEZE PASSAGE. AFTER 19Z ISOLATED THUNDERSTORMS
WILL DEVELOP SOUTH OF THE TERMINAL OVER THE OQUIRRHS. THESE STORMS
ARE EXPECTED TO REMAIN SOUTH OF THE TERMINAL THROUGH THE AFTERNOON,
WITH LESS THAN A 20% CHANCE OF OUTFLOW OR LIGHTNING IMPACTING THE
TERMINAL THIS AFTERNOON.
REST OF UTAH AND SOUTHWEST WYOMING
AFTERNOON SHOWERS AND
THUNDERSTORMS WILL AGAIN DEVELOP ACROSS AREAS MAINLY SOUTH OF I-80,
WHICH COULD IMPACT AREA TERMINALS WITH GUSTY OUTFLOW WINDS,
LIGHTNING, AND BRIEF MVFR VISIBILITY WITHIN HEAVIER RAINFALL. AWAY
FROM THESE STORMS, VFR CONDITIONS WITH TERRAIN DRIVEN WINDS CAN BE
EXPECTED.
FIRE WEATHER
MONSOON MOISTURE WILL CONTINUE TO INCREASE ACROSS
THE AREA THROUGH THE MIDDLE OF NEXT WEEK. THE INCREASE TODAY WILL
BE SUBTLE, BUT MORE SUBSTANTIAL FOR SUNDAY INTO MONDAY. THIS WILL
BRINGING INCREASING COVERAGE OF SHOWERS AND THUNDERSTORMS, A
GREATER LIKELIHOOD OF WETTING RAINS, AND IMPROVED RELATIVE
HUMIDITY VALUES. THERE IS A CHANCE THAT LINGERING CLOUD COVER WILL
LIMIT THE COVERAGE OF CONVECTION ON SOME DAYS, PARTICULARLY AFTER
SUNDAY. CURRENT THINKING IS THAT THE AMOUNT OF MOISTURE WILL PEAK
WEDNESDAY WITH A SLOW DECREASE THEREAFTER.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
SHORT TERM/FIRE WEATHER...TRAPHAGAN
LONG TERM/AVIATION...SEAMAN
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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