673
FXUS65 KSLC 060402
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1002 PM MDT SAT SEP 5 2026
KEY MESSAGES
- MODESTLY BREEZY CONDITIONS WITH GUSTS AROUND 25-40 MPH PERSIST
THROUGH SUNDAY AFTERNOON, PRIMARILY WEST OF THE I-15 CORRIDOR.
- FLASH FLOODING RISK INCREASES SUNDAY, ESPECIALLY FROM SOUTHWEST
TO CENTRAL UTAH AS TROPICAL MOISTURE INCREASES. A FLOOD WATCH IS
IN EFFECT ACCORDINGLY.
- ISOLATED SEVERE STORMS CAPABLE OF STRONG TO SEVERE WIND GUSTS
AND SMALL HAIL WILL BE POSSIBLE ACROSS PORTIONS OF NORTHWEST
UTAH SUNDAY AFTERNOON.
- DRIER CONDITIONS RETURN FOR EARLY NEXT WEEK, WITH UNCERTAINTY
NOTED ON POTENTIAL FOR MORE UNSETTLED CONDITIONS FROM MIDWEEK
ONWARD.
DISCUSSION
EVENING WATER VAPOR ANALYSIS SHOWS A BROAD TROUGH
EXTENDING SOUTHWARD THROUGH THE PACNW WITH DEEP SOUTHERLY FLOW
NOTED LOCALLY OVERHEAD. WHILE A PLUME OF TROPICAL MOISTURE IS
EVIDENT LIFTING NORTHWARD THROUGH THE DESERT SOUTHWEST, MOST
LOCATIONS ACROSS UTAH AND SOUTHWEST WYOMING HAVE REMAINED LARGELY
CLEAR, IF NOT SUNNY. THE SOUTHWESTERLY FLOW HAS RESULTED IN SOME
MODESTLY BREEZY CONDITIONS AROUND THE AREA, BUT TEMPERATURES HAVE
REMAINED SEASONABLY MILD FOR EARLY SEPTEMBER.
THE MOISTURE PLUME WILL CONTINUE TO ADVANCE NORTHWARD OVERNIGHT,
BEGINNING TO ENCROACH INTO SOUTHERN UTAH WITH ASSOCIATED SHOWER
ACTIVITY CLOSER TO SUNRISE. THIS MOISTURE WILL THEN CONTINUE TO
OVERSPREAD THE MAJORITY OF THE FORECAST REGION AS THE DAY
PROGRESSES, WITH PWAT ANOMALIES RISING TO AROUND 150-200% OF
CLIMATOLOGICAL NORMAL. CONCURRENTLY, WILL SEE FLOW OVERHEAD
INCREASE WITH AN EMBEDDED SHORTWAVE SHIFTING THROUGH, PROVIDING
INCREASED SYNOPTIC FORCING FOR ASCENT. WHILE MEAN INSTABILITY IS
ONLY PROGGED TO INCREASE TO AROUND 150-300 J/KG IN THE AFTERNOON,
AND WILL TO A DEGREE BE PREDICATED ON CLOUD COVER AND DEGREE OF
STRATIFORM RAIN, ANTICIPATE THE ENHANCED SYNOPTIC FORCING WILL
ALLOW POCKETS OF EMBEDDED THUNDERSTORMS TO DEVELOP. MODELS SUGGEST
ANY SUCH ACTIVITY WILL HAVE POTENTIAL FOR RAIN RATES IN THE 0.5"
TO 1.0" PER HOUR RANGE, AND WITH THE DEEP MOISTURE, WOULD EXPECT
EVEN SHOWERS WILL BE CAPABLE OF FAIRLY EFFICIENT RAINFALL
PRODUCTION. ADDITIONALLY, CONTINUED MOISTURE ADVECTION IN THE
SOUTHWESTERLY FLOW MAY HELP BRING REDEVELOPING AND/OR TRAINING
STORM ACTIVITY.
GIVEN THE SETUP, SUNDAY WILL SEE POTENTIAL FOR EXCESSIVE RAINFALL
AND INSTANCES OF FLASH FLOODING. THE WPC EXCESSIVE RAINFALL
OUTLOOK INCLUDES SOUTHWESTERN TO CENTRAL UTAH WITHIN A "SLIGHT
RISK" (LEVEL 2 OF 4) OF EXCESSIVE RAINFALL, AND THE MAJORITY OF
THE REMAINDER OF THE FORECAST REGION IN A "MARGINAL RISK" (LEVEL 1
OF 4). GENERAL MODEL CONSENSUS SUPPORTS THE HIGHEST FOCUS OF
ACTIVITY FROM SOUTHWEST UTAH THROUGH CENTRAL UTAH, ESPECIALLY
ALONG THE HIGH TERRAIN AND NEARBY AREAS. FOR NOW, HAVE MAINTAINED
THE ONGOING FLOOD WATCH FOR THIS GENERAL AREA, THOUGH A SHIFT IN
THE PLUME BY EVEN 20 MILES OR SO MAY NECESSITATE EXPANSION OF THE
WATCH AREA. WILL HAVE TO MONITOR TRENDS ACCORDINGLY. PER USUAL,
THE HIGHEST THREAT WILL BE FOR TYPICALLY RAIN SENSITIVE LOCATIONS
SUCH AS RECENT BURN SCARS, SLOT CANYONS, TYPICALLY DRY WASHES, AND
SLICKROCK AREAS. THOSE WITH RECREATION PLANS IN SUCH AREAS SHOULD
STAY WEATHER AWARE AND CONSIDER ALTERNATIVES.
ASIDE FROM THE FLOOD THREAT, MODELS ALSO SUPPORT POTENTIAL FOR
MORE ISOLATED CONVECTION FORMING ON THE PERIPHERY OF THIS PLUME,
PARTICULARLY IN PORTIONS OF NORTHWEST UTAH. WHILE ALSO DEPENDENT
TO AN EXTENT ON THE DEGREE OF DESTABILIZATION, THE ENHANCED FLOW
ALOFT WILL RESULT STRONG DEEP LAYER SHEAR IN EXCESS OF 40 KTS OR
SO. THIS AREA WILL ALSO BE NEARER A SLOWLY APPROACHING FRONT FROM
THE LARGER PACNW TROUGH. WHILE CONDITIONAL, ANY STORMS THAT CAN
BECOME BETTER ORGANIZED WILL HAVE AT LEAST SOME THREAT OF STRONG
TO SEVERE WIND GUSTS AND SMALL HAIL.
PRECIPITATION WILL GRADUALLY DIMINISH OVERNIGHT MOVING INTO
MONDAY MORNING AS THE MOISTURE PLUME EXITS AND THE DEEP PACNW
TROUGH'S EVOLUTION WILL ALLOW A DRIER AND MORE ZONAL FLOW TO
DEVELOP. THE ASSOCIATED COLD FRONT WILL ALSO PROGRESS AS FAR SOUTH
AS CENTRAL UTAH IN VICINITY OF THE I-70 CORRIDOR OR SO, BRINGING
COOLER TEMPERATURES BEHIND IT. AFTERNOON HIGHS BEHIND THE FRONT
MONDAY WILL TEND TO RUN AROUND 5-10 DEGREES BELOW NORMAL, WITH
TEMPERATURES AHEAD OF IT NEAR TO SLIGHTLY BELOW NORMAL. THE FRONT
WILL BEGIN TO WASH OUT QUICKLY, WITH TEMPERATURES FOR TUESDAY
MODERATING BACK UPWARDS NEARER TO TYPICAL LEVELS.
UNCERTAINTY INCREASES FROM WEDNESDAY ONWARD WITH MODELS DIVERGING
ON THE EXACT PATTERN EVOLUTION. THERE IS SUPPORT THAT MID TO
UPPER LEVEL RIDGING WILL BE CENTERED SOMEWHERE IN THE SOUTHWEST
CONUS, BUT WITH VARYING PLACEMENTS. IF CENTERED MORE ATOP THE FOUR
CORNERS REGION THE LOCAL AREA WILL SEE BETTER POTENTIAL FOR
MOISTURE RETURNING, WITH DECREASING FAVORABILITY THE FURTHER TO
THE WEST IT ENDS UP. AROUND 30% OF ENSEMBLES SUPPORT A MORE MARKED
MOISTURE SURGE AND HIGHER PRECIPITATION POTENTIAL, AROUND 30%
HAVE A MORE MUTED MOISTURE RETURN AND LIKELY MORE ISOLATED
PRECIPITATION POTENTIAL, AND THE REMAINING 40% REMAIN ON THE DRIER
SIDE OF THE ENVELOPE.
AVIATION, ISSUED 701 PM MDT SAT SEP 5 2026
KSLC...SOUTHERLY WINDS REMAIN GENERALLY LIGHT OVERNIGHT INTO SUNDAY
MORNING, GRADUALLY INCREASING AFTER 14Z. WINDS FURTHER INCREASE
AROUND 20Z, WITH GUSTS EXCEEDING 25 KTS DEVELOPING THROUGH THE
EVENING. AN INFLUX OF TROPICAL MOISTURE INTO NORTHERN UTAH WILL
RESULT IN GRADUALLY INCREASING CLOUD COVER AND LOWERING CIGS SUNDAY
MORNING. STEADY RAINFALL IS EXPECTED TO MOVE INTO THE VICINITY OF
THE TERMINAL AFTER 20Z, WITH POTENTIAL TO PRODUCE BRIEF MVFR CIGS
THROUGH THE EVENING.
REST OF UTAH AND SOUTHWEST WYOMING...GUSTY SOUTHERLY WINDS ACROSS
THE AIRSPACE TAPER OVERNIGHT BEFORE INCREASING GRADUALLY AFTER
ROUGHLY 13-16Z. WIND GUSTS IN EXCESS OF 25 KTS ARE EXPECTED TO
DEVELOP THROUGH THE AFTERNOON FOR MOST REGIONAL TERMINALS. AN INFLUX
OF TROPICAL MOISTURE INTO THE REGION WILL RESULT IN GRADUALLY
INCREASING CLOUD COVER OVERNIGHT INTO SUNDAY MORNING, WITH LOWERING
CIGS AS WIDESPREAD RAIN MOVES IN FROM THE SOUTH THROUGH THE DAY.
SHOWERS AND THUNDERSTORMS TAPER OFF BY EARLY MONDAY MORNING.
FIRE WEATHER, ISSUED 208 PM MDT SAT SEP 5 2026
MOISTURE WILL CONTINUE TO GRADUALLY INCREASE INTO
SUNDAY AS SOUTHWESTERLY FLOW PUSHES MOISTURE FURTHER NORTH.
THIS AFTERNOON, EXPECT LOCALLY CRITICAL FIRE WEATHER CONDITIONS
PRIMARILY ACROSS THE WEST DESERT AND GREAT SALT LAKE DESERT WHERE
HUMIDITIES HAVE BEEN OBSERVED DROPPING BELOW 15%. ADDITIONALLY,
STRONG WIND GUSTS ACROSS AREAS PRIMARILY WEST OF I-15 WILL RANGE
FROM 30-45MPH EACH AFTERNOON INTO SUNDAY.
ON SUNDAY, A STRONGER PUSH OF MOISTURE ARRIVES TO UTAH WITH
WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE STATE, THOUGH
PRIMARILY ACROSS CENTRAL AND SOUTHERN UTAH. THE HIGHEST RAINFALL
TOTALS ARE EXPECTED ACROSS HIGHER TERRAIN OF CENTRAL AND SOUTHERN
UTAH, THOUGH LOWER ELEVATION AREAS FURTHER EAST MAY SEE HIGHER
ISOLATED TOTALS FROM STRONGER STORMS. FOR LOWER LYING AREAS WEST OF
I-15, GENERALLY A TRACE OR LESS OF PRECIPITATION IS EXPECTED ON
SUNDAY. A DRYING TREND IS EXPECTED TO DEVELOP MONDAY AND TUESDAY
WITH MORE PRECIPITATION EXPECTED AFTER MIDWEEK NEXT WEEK ACROSS AT
LEAST SOUTHERN AND CENTRAL UTAH.
SLC WATCHES/WARNINGS/ADVISORIES
UT...FLOOD WATCH FROM 9 AM MDT SUNDAY THROUGH SUNDAY EVENING FOR
UTZ113-114-116>120-122-124>128.
WY...NONE.
PUBLIC...WARTHEN
AVIATION...WHITLAM
FIRE WEATHER...WORSTER
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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