721
FXUS65 KSLC 210418
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1018 PM MDT MON JUL 20 2026
KEY MESSAGES
- DAILY SCATTERED SHOWERS AND THUNDERSTORMS WILL PERSIST ACROSS
THE REGION AS A MONSOONAL PATTERN REMAINS. MONDAY THROUGH WEDNESDAY
NIGHT WILL ALSO SEE A PATTERN FAVORABLE FOR CONTINUATION OF
NOCTURNAL SHOWERS AND THUNDERSTORMS.
- FLASH FLOODING WILL CONTINUE TO REMAIN AN ONGOING THREAT ACROSS
MUCH OF THE REGION. A MARGINAL RISK (CATEGORY 1/4) HIGHLIGHTS
MORE OR LESS ALL OF THE FORECAST AREA THROUGH FRIDAY, WITH A
SLIGHT RISK (CATEGORY 2/4) ALSO HIGHLIGHTING MUCH OF THE AREA
TUESDAY AND WEDNESDAY.
- ISOLATED STRONG WIND GUSTS 35-55 MPH AND SMALL HAIL WILL BE
POSSIBLE IN STRONGER STORMS, IN ADDITION TO LIGHTNING AND HEAVY
RAIN.
DISCUSSION
SYNOPTIC PATTERN THIS EVENING REMAINS QUITE SIMILAR TO
THAT OF PREVIOUS DAYS. A BROAD RIDGE REMAINS EXTENDED FROM THE
SOUTH/CENTRAL PLAINS ON INTO THE FOUR CORNERS REGION. AROUND THE
SOUTH TO WESTERN PERIPHERY OF THIS RIDGE A VERY FAVORABLE MOISTURE
TAP REMAINS, WITH WIDESPREAD PWAT VALUES IN EXCESS OF 1", AROUND
150% TO 200% OF CLIMATOLOGICAL NORMAL. WHILE MONDAY HAS SEEN
GENERALLY LESS COVERAGE OF ASSOCIATED SHOWERS AND THUNDERSTORMS,
WHAT HAS FORMED HAS BEEN AIDED BY A SLIGHTLY ENHANCED MOIST
SOUTHEAST TO EASTERLY INFLOW, HELPING KEEP ACTIVITY SEEMINGLY NEAR
STATIONARY DESPITE MORE FLOW.
FOR TONIGHT INTO TUESDAY, A SUBTLE EMBEDDED SHORTWAVE WILL SHIFT
NORTHWESTWARD INTO THE AREA THROUGH NW NM/SW CO. WHILE DAYTIME
HEATING HAS CEASED, THE MILD AND MOISTURE RICH ENVIRONMENT WILL
CONTINUE TO SUPPORT MODEST INSTABILITY ON THE ORDER OF 100-200
J/KG OR SO. WITH THE EXTRA SYNOPTIC SUPPORT FROM THIS SHORTWAVE,
MODELS CONTINUE TO SHOW SOME SUPPORT FOR CONTINUED OR RENEWED
NOCTURNAL CONVECTION SHIFTING WESTWARD THROUGH THE STATE FROM
MIDNIGHT THROUGH SUNRISE TUESDAY. WHILE ACTIVITY IS LIKELY TO BE A
BIT LESS ORGANIZED/WEAKER WITH THE MORE LIMITED INSTABILITY,
EVENING CAM GUIDANCE DOES SUGGEST RAINFALL RATES UP TO AROUND 0.5"
TO 0.75" PER HOUR IN WHAT STRONGER CORES DO DEVELOP. AS SUCH,
WILL NEED CONTINUE MONITOR RAIN SENSITIVE BASINS OVERNIGHT. GIVEN
THE OVERNIGHT TIMING, THOSE IN SUCH AREAS SHOULD BE SURE TO HAVE A
WAY TO RECEIVE WEATHER ALERTS IF STRONGER STORMS DO DEVELOP/HOLD
TOGETHER.
TUESDAY WILL SEE THIS SHORTWAVE SHIFT INTO UTAH, AND MOISTURE
WILL CONTINUE TO FURTHER INCREASE WITH PWATS RISING AROUND THE
200% TO 250% OF NORMAL RANGE. IN GENERAL, THIS COMBINATION WITH
VERY AMPLE MOISTURE AND INCREASED SYNOPTIC SUPPORT/FLOW SHOULD
SUPPORT WIDESPREAD SCATTERED SHOWER AND THUNDERSTORM DEVELOPMENT.
MODELS SUGGEST AS MUCH, AND DEPICT POTENTIAL FOR ACTIVITY CAPABLE
OF RAINFALL RATES IN THE 1" TO 1.5" PER HOUR RATE, IF NOT POSSIBLY
MORE IN THE STRONGEST ACTIVITY THAT FORMS. THE EXTRA FLOW WILL
TEND TO HELP ACTIVITY MOVE A BIT MORE THAN PREVIOUS DAYS, WITH THE
CAVEAT THAT AREAS OF CONTINUED MOIST INFLOW WILL HAVE POTENTIAL
TO RESULT IN BACKBUILDING OVER THE SAME AREA. AS SUCH, THE FLOOD
POTENTIAL WILL ONCE AGAIN BE ELEVATED TUESDAY, ESPECIALLY FOR RAIN
SENSITIVE AREAS SUCH AS BURN SCARS, SLOT CANYONS, TYPICALLY DRY
WASHES, AND SLICKROCK AREAS. THE WPC EXCESSIVE RAINFALL OUTLOOK
HIGHLIGHTS THE ENTIRE FORECAST REGION IN A MARGINAL RISK (CATEGORY
1/4), AND THE VAST MAJORITY OF UTAH (GENERALLY SOUTH OF THE I-80
CORRIDOR) IN A SLIGHT RISK (CATEGORY 2/4) OF EXCESSIVE RAINFALL.
WITH THAT, SOUTHERN AND CENTRAL UTAH WILL HAVE A FLOOD WATCH IN
EFFECT TUESDAY FOR THE POTENTIAL FOR FLASH FLOODING. ALL THAT
SAID, WILL NEED TO KEEP AN EYE ON THE OVERNIGHT TO EARLY AFTERNOON
EVOLUTION. IF THE NOCTURNAL ACTIVITY RESULTS IN WIDESPREAD
LINGERING CLOUD COVER OR STRATIFORM PRECIPITATION, IT COULD HELP
SUPPRESS ACTIVITY TUESDAY. ADDITIONALLY, THE ABUNDANCE OF MOISTURE
COULD RESULT IN ACTIVITY DEVELOPING QUICK ENOUGH AND WIDESPREAD
ENOUGH TO LIMIT MORE OF THE INDIVIDUAL STORM POTENTIAL, CLOUD
THINGS OVER, AND LIMIT THE THREAT. AGAIN THOUGH, OTHERWISE THE
INGREDIENTS ARE IN PLACE FOR ANOTHER DAY WITH A FLASH FLOODING
THREAT. ASIDE FROM THE FLASH FLOOD THREAT, THE SLIGHT ENHANCEMENT
TO SHEAR (AROUND 20-30 KTS) WITH THE SHORTWAVE WILL GIVE SOME
POTENTIAL FOR A FEW STRONGER, LONGER-LIVED MORE ORGANIZED STORMS
CAPABLE OF GUSTY OUTFLOW WINDS UP TO AROUND 55 MPH OR SO AS WELL
AS SMALL HAIL.
TUESDAY NIGHT INTO EARLY WEDNESDAY WILL ONCE AGAIN SEE NOCTURNAL
SHOWERS AND THUNDERSTORMS LINGERING, BEFORE GIVING WAY TO A DAY
THAT WILL LIKELY SEE A SIMILAR EVOLUTION TO THAT OF TUESDAY. LIKE
TUESDAY, THERE WILL ALSO BE SOME QUESTION OF THE EXACT EVOLUTION
JUST GIVEN THE AMOUNT OF MOISTURE AND LIKELIHOOD OF PRECEDING
NOCTURNAL ACTIVITY. PROVIDED THIS DOESN'T HELP LIMIT ACTIVITY,
ULTIMATELY EXPECT A DAY THAT WILL ONCE AGAIN SEE WIDESPREAD
SCATTERED SHOWERS AND THUNDERSTORMS CAPABLE OF EFFICIENT RAINFALL
PRODUCTION, POSING A FLASH FLOOD THREAT PARTICULARLY TO RAIN
SENSITIVE BASINS. ONE INTERESTING SIGNAL THAT IS NOTED IS THAT ON
WEDNESDAY THE ECMWF EXTREME FORECAST INDEX HIGHLIGHTS MUCH OF
NORTHERN UTAH TO SOUTHWEST WYOMING PARTICULARLY TO INDICATE
CLIMATOLOGICALLY ANOMALOUS PRECIPITATION POTENTIAL, SOMETHING NOT
NOTED ON TUESDAY. LIKE TUESDAY, WEDNESDAY WILL ALSO SEE SOME
POTENTIAL FOR A FEW STRONGER STORMS CAPABLE OF STRONG GUSTY WINDS
AND SMALL HAIL, IN ADDITION TO HEAVY RAINFALL AND FREQUENT
LIGHTNING.
THURSDAY ONWARD WILL SEE A BIT OF UNCERTAINTY IN THE DAY TO DAY
EVOLUTION, BUT IN GENERAL THE PLACEMENT OF THE RIDGE WILL REMAIN
FAVORABLE FOR PERIODS OF MONSOONAL MOISTURE INFLUX INTO THE
REGION. ENSEMBLE MEAN PWAT ANOMALIES FALL BACK GENERALLY INTO THE
100% TO 150% RANGE, THOUGH INDIVIDUAL MEMBERS SHOW POTENTIAL FOR
PERIODS OF BOTH DRIER AND MOISTER THAN THAT. ADDITIONALLY, THERE
SEEMS TO BE SOME SPLIT IN THE GENERAL ENSEMBLE SUITE, WITH ECMWF
MEMBERS MORE BULLISH ON A CONTINUATION OF A MORE FAVORABLE
MOISTURE TAP, AND GEFS MEMBERS MORE ON THE DRIER SIDE, THOUGH NOT
NECESSARILY IN A WAY THAT WOULD FULLY SHUT DOWN POTENTIAL FOR
SHOWERS AND THUNDERSTORMS ACROSS THE ENTIRE REGION. FOR NOW, WILL
JUST NEED TO KEEP AN EYE ON THE DAY TO DAY TRENDS, AS SMALL SHIFTS
IN THE RIDGE AND ANY POTENTIAL GULF MOISTURE RICH INVERTED
TROUGHS WILL RESULT IN NOTABLE SHIFTS IN WHERE THE HIGHEST
PRECIPITATION POTENTIAL WILL BE LOCALLY. THOSE NEAR RAIN SENSITIVE
BASINS OR PLANNING TRAVEL/RECREATION WILL CERTAINLY WANT TO
CONTINUE TO MONITOR THE FORECAST FOR POTENTIAL IMPACTS.
AVIATION, ISSUED 617 PM MDT MON JUL 20 2026
KSLC...DOWNSLOPING EASTERLY WIND GUSTS DUE TO CONVECTIVE ACTIVITY
OVER THE WASATCH WILL CONTINUE THROUGH AROUND 01Z BEFORE
DECREASING AND EASING BACK NORTHWESTERLY THROUGH THE REMAINDER OF
THE NIGHT. NOCTURNAL SHOWER ACTIVITY WILL RESULT IN PERIODS OF
VARIABLE WINDS AT THE TERMINAL BETWEEN ROUGHLY 07-11Z TONIGHT,
WITH GUSTS EXCEEDING 25 KTS POSSIBLE THROUGH THIS PERIOD. WINDS
INCREASE OUT OF THE NORTHWEST AFTER 18Z, BEFORE CONVECTIVE
ACTIVITY DEVELOPING AFTER 20Z BRINGS MORE GUSTY AND ERRATIC WINDS
THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING. VFR CONDITIONS
PREVAIL AT THE TERMINAL, THOUGH HEAVIER RAINFALL TOMORROW
AFTERNOON AND EVENING COULD RESULT IN BRIEF MVFR CONDITIONS.
REST OF UTAH AND SOUTHWEST WYOMING...CONVECTIVE ACTIVITY DWINDLES
THROUGH THE REMAINDER OF THE EVENING. THERE IS A THREAT FOR
NOCTURNAL SHOWERS AND THUNDERSTORMS OVERNIGHT ACROSS MOST OF THE
AIRSPACE, MAINLY BETWEEN THE 07-12Z TIMEFRAME; THIS ACTIVITY WILL
BE CAPABLE OF PRODUCING VARIABLE GUSTY WINDS FOR MOST REGIONAL
TERMINALS OVERNIGHT. OTHERWISE, WIDELY SCATTERED SHOWERS AND
THUNDERSTORMS REDEVELOP AFTER AROUND 19Z ON TUESDAY, WITH MVFR
CONDITIONS POSSIBLE FOR MANY TERMINALS THROUGH THE EVENING AS
HEAVY RAINFALL MAY BRING LOWERED CIGS/VIS AT TIMES.
FIRE WEATHER
MONSOONAL MOISTURE REMAINS ACROSS UT INCREASING
HUMIDITIES WHILE RAISING CHANCES FOR SHOWERS AND THUNDERSTORMS
ACROSS THE STATE MODERATING FIRE WEATHER CONDITIONS OVERALL.
CHANCES FOR SHOWERS AND THUNDERSTORMS CONTINUE TO BE ELEVATED
ACROSS CENTRAL AND SOUTHERN UT THIS AFTERNOON, AND THE UINTAS
RANGING FROM 50-80%. A WETTING RAIN REMAINS FAVORED THIS AFTERNOON
ACROSS EACH MENTIONED LOCATION. EXPECT SHOWERS AND THUNDERSTORMS
TO DEVELOP ALONG HIGHER TERRAIN PARALLEL TO I-15 EACH AFTERNOON
OVER THE NEXT SEVERAL DAYS AROUND 1200-1400 WITH GUSTY OUTFLOW
WINDS, HEAVY RAINFALL, AND LIGHTNING. WINDS WILL GENERALLY REMAIN
LIGHT TERRAIN DRIVEN / DIURNAL OVER THE NEXT SEVERAL DAYS. CHANCES
FOR SHOWERS AND THUNDERSTORMS INCREASE ACROSS NORTHERN UT
STARTING TUESDAY WITH NOTABLY HIGHER CHANCES ACROSS THE ENTIRETY
OF UT TUESDAY AND WEDNESDAY AFTERNOONS.
SLC WATCHES/WARNINGS/ADVISORIES
UT...HEAT ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR UTZ101>105.
FLOOD WATCH FROM TUESDAY AFTERNOON THROUGH LATE TUESDAY NIGHT
FOR UTZ113-115>131.
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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