636  
FXUS65 KSLC 182126  
AFDSLC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SALT LAKE CITY UT  
326 PM MDT THU SEP 18 2025  
   
SYNOPSIS
 
MOISTURE BEGINS TO RETURN TO THE FORECAST AREA THIS  
EVENING WITH GUSTY SHOWERS ACROSS SOUTHWEST UT THIS EVENING.  
CHANCES FOR SHOWERS AND THUNDERSTORMS ACROSS THE STATE INCREASE  
THROUGH THE WEEKEND BEFORE A DRYING TREND TAKES HOLD ONCE AGAIN  
EARLY NEXT WEEK.  
 

 
   
SHORT TERM (THROUGH 12Z/6AM SATURDAY)
 
CURRENTLY, OUR PERSISTENT  
UPPER LOW HAS OFFICIALLY CLEARED THE AREA AND IS PHASING INTO THE  
MEAN UPPER FLOW OVER THE FAR NORTHERN PLAINS / NORTHERN HIGH PLAINS.  
IN ITS WAKE, A SHORTWAVE RIDGE IS BUILDING IN OVER UT AND SOUTHWEST  
WY WITH TROPICAL MOISTURE PHASING INTO A SHORTWAVE TROUGH OVER  
SOUTHERN CA. THIS SHORTWAVE TROUGH IS FORECAST TO SLIDE NORTHEAST  
WHILE GRADUALLY ERODING THE RIDGE OVER THE FORECAST AREA TO THE  
SOUTHEAST SOMEWHAT RESULTING IN ENHANCED MOISTURE TRANSPORT OVER THE  
FORECAST AREA AND PROVIDING ENOUGH ASCENT FOR SCATTERED SHOWERS AND  
THUNDERSTORMS ACROSS THE FORECAST AREA THIS WEEKEND.  
 
ANALYZED PWATS PER MESOANALYSIS ACROSS THE STATE SIT AROUND ROUGHLY  
0.5" OF WATER OR LESS AS THE RIDGE SITS OVERHEAD. HOWEVER, ROBUST  
MOISTURE IS BEING OBSERVED ACROSS SOUTHERN NV WHICH IS EXPECTED TO  
ADVECT NORTH THROUGHOUT TODAY AND THIS EVENING INTO SOUTHERN UT. AN  
INITIAL PUSH OF MOISTURE IS EXPECTED FOLLOWING 6PM THIS EVENING  
ACROSS FAR SOUTHWESTERN UT WHICH MAY RESULT IN SCATTERED DRY  
THUNDERSTORMS CAPABLE OF GUSTY WINDS. WHILE MOISTURE QUALITY IS  
EXPECTED TO DIMINISH WITH NORTHEASTERN EXTENT, PWATS IN EXCESS OF  
AROUND 1" ARE EXPECTED TO OVERSPREAD SOUTHERN UT BY 12Z (6AM)  
FRIDAY. HI-RES GUIDANCE ALSO INDICATES THAT SOME LOCALIZED PWATS MAY  
BE IN EXCESS OF AROUND 1.2-1.3" ACROSS FAR SOUTHWESTERN UT,  
PARTICULARLY ACROSS LOWER WASHINGTON COUNTY.  
 
THIS PARAMETER SPACE MAY RAISE SOME EYEBROWS, THOUGH THERE ARE TWO  
FACTORS WORKING AGAINST IT. FIRST, ASCENT APPEARS BROAD AND WEAK  
WHICH MAY RESULT IN STORMS STRUGGLING TO BECOME MORE ROBUST AND  
SUSTAINED FOR A LONGER TIME. SECOND, THE MORNING HOURS SEEM MORE  
CONDUCIVE TOWARD A FLOODING RAIN THREAT ACROSS SOUTHERN UT AS IT  
APPEARS TO POSSESS THE MOST FAVORABLE OVERLAP OF STRONGER ASCENT  
WITH THE INITIAL PUSH OF DEEPER MOISTURE. CLOUD COVER IS EXPECTED TO  
DIMINISH IN THE AFTERNOON HOURS, WITH GUIDANCE INDICATING THAT A  
GOOD AMOUNT OF THE MOISTURE WILL BEGIN TO MIX OUT. THIS WOULD NOT BE  
NEARLY AS FAVORABLE FOR HEAVY RAINFALL GIVEN WEAKER ASCENT. HOWEVER,  
TERRAIN DRIVEN STORMS REMAIN POSSIBLE LATER ON IN THE AFTERNOON WITH  
LOCALLY HEAVIER RAINFALL POSSIBLE.  
 
FURTHER NORTH ACROSS CENTRAL UT IN THE AFTERNOON HOURS, STORMS MAY  
FORM ACROSS THE HIGHER TERRAIN ACROSS CENTRAL UT AND ACROSS THE WEST  
DESERT AS MOISTURE CONTINUES TO SURGE NORTH. GIVEN THE LOWER LEVELS  
ARE EXPECTED TO REMAIN RELATIVELY DRY, GUSTY AND ERRATIC WINDS  
APPEAR POSSIBLE WITH ANY STORM THAT DEVELOPS ACROSS THE AREA. THESE  
STORMS ARE EXPECTED TO WEAKEN AS SUNSET DRAWS NEAR WITH MOSTLY  
ISOLATED SHOWERS SCATTERED ACROSS THE FORECAST AREA DURING THE  
OVERNIGHT HOURS.  
 
   
LONG TERM (AFTER 12Z/6AM SATURDAY), ISSUED 348 AM MDT
 
 
ABOVE-NORMAL MOISTURE WILL BE  
IN PLACE AT THE START OF THE LONG-TERM PERIOD, REACHING UP TO 200%  
OF NORMAL ACROSS WESTERN UTAH (150% ACROSS EASTERN UTAH/SOUTHWEST  
WYOMING). MID-LEVEL FLOW WILL BE LARGELY ZONAL ON SATURDAY, THOUGH  
WEAK SYNOPTIC DYNAMICS FROM A 80-90KT JET STREAK AND SUBTLE  
SHORTWAVE TROUGH WILL HELP SCATTERED SHOWERS AND THUNDERSTORMS TO  
DEVELOP ACROSS THE FORECAST AREA BY SATURDAY AFTERNOON. DESPITE  
APPRECIABLE COLUMN MOISTURE, MODEL SOUNDINGS ACTUALLY SUGGEST THAT  
DRIER AIR WILL MOVE INTO THE MID LEVELS ACROSS THE STATE,  
POTENTIALLY LIMITING CONVECTIVE DEVELOPMENT AND FLASH FLOOD  
POTENTIAL. BY SUNDAY, THIS TREND WILL CONTINUE, WITH MOST CONVECTION  
EXPECTED ACROSS NORTHERN UTAH AND PRIMARILY OVER HIGHER TERRAIN  
GIVEN AN OVERALL LACK OF SYNOPTIC LIFT.  
 
BY LATE SUNDAY, A GRAZING TROUGH WILL ADVECT MUCH DRIER AIR INTO THE  
REGION, WITH PWATS DIPPING DOWN TO 50% OF NORMAL BY LATE MONDAY.  
INTERESTINGLY, THERE ARE STILL ROUGHLY 20% OF ENSEMBLE MEMBERS THAT  
ACTUALLY FAVOR A STRONGER TROUGH OVERHEAD INSTEAD OF JUST GRAZING  
OUR AREA; THIS COULD PRODUCE COOLER AND WETTER CONDITIONS TO START  
THE WORK WEEK, IF THIS SCENARIO WERE TO PAN OUT. HIGH PRESSURE WILL  
THEN BUILD OVER UTAH BEHIND THIS TROUGH, THOUGH FORECAST CONFIDENCE  
DECREASES SIGNIFICANTLY AFTER TUESDAY. MODELS CAN AGREE ON THE  
DEVELOPMENT OF A CUTOFF LOW OVER SOCAL, BUT THEY DIVERGE GREATLY  
WITH REGARDS TO WHERE/WHEN THIS LOW MOVES BY MID-WEEK. ULTIMATELY,  
THIS WILL IMPACT HOW LONG HIGH PRESSURE RESIDES OVER OUR AREA. BY  
DAY 7/THURSDAY, NOW 61% OF ENSEMBLE MEMBERS FAVOR HIGH PRESSURE  
STILL OVERHEAD, WITH OR WITHOUT AN STRONG UPSTREAM TROUGH. ANOTHER  
23% FAVOR A WEAK TROUGH, WHILE THE REMAINING 16% ARE STILL HANGING  
ONTO A POTENT TROUGH OVER THE WESTERN US...LOWER THAN WHERE CHANCES  
WERE YESTERDAY.  
 

 
   
AVIATION...KSLC
 
VFR CONDITIONS WILL PERSIST FOR THE KSLC  
TERMINAL THROUGH THE PERIOD. DRY CONDITIONS WILL CONTINUE WITH SOME  
INCREASING MID LEVEL CLOUDS. WINDS WILL REMAIN LIGHT AND DIURNALLY  
DRIVEN.  
   
REST OF UTAH AND SOUTHWEST WYOMING
 
VFR CONDITIONS WILL PERSIST  
FOR THE ENTIRE AIRSPACE THROUGH THE PERIOD. DRY CONDITIONS WITH  
LIGHT AND DIURNALLY DRIVEN WINDS WILL CONTINUE ACROSS THE NORTH WITH  
INCREASING MID LEVEL CLOUDS. ACROSS THE SOUTH MOISTURE WILL INCREASE  
WITH A MIX OF STRATIFORM PRECIPITATION AND ISOLATED CONVECTION  
OVERNIGHT. WINDS ACROSS THE SOUTH WILL BE LIGHT AND DIURNALLY DRIVEN  
ASIDE FROM GUSTY ERRATIC WINDS ASSOCIATED WITH ANY CONVECTION  
OVERNIGHT.  
 

 
   
FIRE WEATHER
 
HIGH PRESSURE IS EXPECTED TO GRADUALLY SLIDE EAST  
THIS EVENING AS MOISTURE BEGINS TO PUSH INTO UT VIA PERSISTENT  
SOUTHWESTERLY WINDS THROUGH THE WEEKEND INCREASING HUMIDITIES ACROSS  
THE STATE. DRY THUNDERSTORMS APPEAR POSSIBLE WITH THE INITIAL  
MOISTURE SURGE THIS EVENING ACROSS FAR SOUTHWESTERN UT AHEAD OF  
BETTER MOISTURE. COVERAGE FOR SHOWERS AND THUNDERSTORMS SEE AN  
INCREASE TOMORROW WITH BETTER MOISTURE MOVING IN ACROSS SOUTHERN AND  
CENTRAL UT FEATURING THE BEST CHANCE FOR A WETTING RAIN OVER THE  
NEXT FEW DAYS. ON SATURDAY AND SUNDAY, CHANCES FOR SHOWERS AND  
THUNDERSTORMS SHIFT TO NORTHERN UT BEFORE ANOTHER DRYING TREND TAKES  
HOLD ON MONDAY.  
 

 
   
SLC WATCHES/WARNINGS/ADVISORIES
 
 
UT...NONE.  
WY...NONE.  

 
 

 
 
SHORT TERM...WORSTER  
LONG TERM...CUNNINGHAM  
AVIATION...MAHAN  
FIRE WEATHER...WORSTER  
 
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...  
HTTP://WEATHER.GOV/SALTLAKECITY  
 
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