726
FXUS65 KSLC 180942
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
342 AM MDT FRI JUL 18 2025
SYNOPSIS
MONSOON MOISTURE WILL RESULT IN THE DEVELOPMENT OF
SHOWERS AND THUNDERSTORMS ACROSS MUCH OF UTAH AND SOUTHWEST
WYOMING THIS AFTERNOON INTO THE EVENING. THE AREA WILL SEE A
GRADUAL DRYING TREND FOR THE WEEKEND AND INTO EARLY NEXT WEEK.
SHORT TERM (THROUGH 12Z/6AM SUNDAY)
UTAH AND SOUTHWEST WYOMING
REMAIN UNDER SOUTHERLY FLOW TODAY ON THE BACK SIDE OF A RIDGE
CENTERED OVER NEW MEXICO. THE FLOW IS BEING ENHANCED BY A LOW
PRESSURE SYSTEM OFF THE NORTHERN BAJA COAST. THIS FLOW IS
ADVECTING MONSOON MOISTURE NORTHWARD INTO THE AREA. SATELLITE
DERIVED PWS INDICATE PW VALUES IN THE 0.8 TO 1.0 INCH RANGE ACROSS
THE SOUTHERN TWO-THIRDS OF THE FORECAST AREA WITH VALUES IN THE
0.6 TO 0.8 INCH RANGE ELSEWHERE. THE MOISTURE WILL CONTINUE ITS
NORTHWARD MOVEMENT TODAY, WITH THOSE HIGHER VALUES SPREADING UP
TOWARD THE UTAH/IDAHO BORDER BY EARLY AFTERNOON.
IN THIS MOIST AND UNSTABLE AIRMASS, ANOTHER ROUND OF SHOWERS AND
THUNDERSTORMS WILL DEVELOP THIS AFTERNOON, THIS TIME WITH GOOD
COVERAGE ACROSS MUCH OF THE FORECAST AREA. GIVEN A RELATIVE
DECREASE IN MOISTURE OVER SOUTHERN UTAH, THE FLASH FLOOD THREAT
REMAINS ENHANCED BUT LOOKS A BIT WEAKER COMPARED TO YESTERDAY.
OVER NORTHWEST UTAH, GUIDANCE INDICATES THAT SHORTWAVE ENERGY
EJECTING FROM THE BAJA LOW COULD INTERACT WITH A BOUNDARY,
PRODUCING AN AREA OF BETTER DYNAMICS. GIVEN THAT MOISTURE WILL BE
SLOWER TO ARRIVE IN THIS AREA AND MORE HIGH BASED, THE PRIMARY
THREAT IN THIS AREA WOULD BE GUSTY, MICROBURST WINDS. SPC HAS PUT
THIS AREA IN A MARGINAL RISK FOR SEVERE THUNDERSTORMS IN ITS
LATEST OUTLOOK.
ANOTHER PACIFIC NORTHWEST STORM SYSTEM IS ON TRACK TO MOVE ONSHORE
TONIGHT INTO SATURDAY, SHIFTING THE FLOW ALOFT OVER UTAH AND
SOUTHWEST WYOMING TO A MORE WESTERLY DIRECTION. DRYING WILL BE
INITIALLY SLOW, SO SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS
ARE ANTICIPATED SATURDAY AFTERNOON. HOWEVER, DRYING WILL BE MORE
PRONOUNCED ON SUNDAY, FURTHER DECREASING COVERAGE OF CONVECTION.
LONG TERM (AFTER 12Z/6AM SUNDAY)
A LONGWAVE TROUGH WILL DIG INTO
THE PACNW SUNDAY, WHILE A RIDGE WILL BE IN PLACE FOR THE SOUTHERN
PLAINS AND SOUTHEAST U.S. AS THE RIDGE TRACKS CLOSER TO SOUTHWEST
WYOMING AND UTAH, SOUTHWEST FLOW WILL ENHANCE. GUSTS WILL LIKELY
EXCEED 20 MPH FOR PORTIONS OF SOUTHWEST UTAH, WITH THE SOUTHWEST
FLOW ADVECTING DRIER CONDITIONS IN. SHOWERS AND THUNDERSTORMS WILL
BE MUCH MORE ISOLATED THAN THE START OF THE WEEKEND AND LARGELY BE
NEAR MOUNTAINOUS TERRAIN. SOUTHWEST WINDS WILL LIKELY NOT WARRANT
RED FLAG WARNINGS, BUT WITH THE STRONGER WINDS AND AFTERNOON
RELATIVE HUMIDITY IN THE TEENS, FIRE DANGER WILL INCREASE.
THE LONGWAVE TROUGH TO THE NORTHWEST WILL BECOME POSITIVELY-TILTED
MONDAY. THAT WILL BRING AN INCREASE IN SOUTHWEST WINDS, WHILE
RELATIVE HUMIDITY REMAINS LOW. CRITICAL FIRE WEATHER CONDITIONS
BECOME LIKELY MONDAY AFTERNOON, WITH WEST TO SOUTHWEST WINDS GUSTING
IN EXCESS OF 25 MPH THROUGHOUT SOUTHWEST WYOMING AND MOST OF WESTERN
UTAH. RELATIVE HUMIDITY VALUES WILL LIKELY RANGE FROM THE SINGLE
DIGITS TO TEENS. SHOWER AND THUNDERSTORM CHANCES WILL LOWER FURTHER
FROM SATURDAY, WITH ONLY ISOLATED SHOWERS AND THUNDERSTORMS IN THE
MOUNTAINS.
THE LONGWAVE TROUGH WILL LIFT NORTHWARD TUESDAY. THAT WILL BRING A
SLIGHT DOWNTREND IN WINDS, BUT CONTINUED GUSTS IN EXCESS OF 20 MPH
AND LOW RELATIVE HUMIDITY WILL BRING POTENTIAL RED FLAG CONDITIONS
TO THE SAME LOCATIONS.
THERE IS GOOD MODEL AGREEMENT THAT THE RIDGE THAT WILL PREVAIL TO
THE SOUTHEAST WILL RETROGRADE MUCH OF THE WEEK. AS HIGH PRESSURE
BUILDS IN FROM THE SOUTHEAST, SOUTHWEST WYOMING AND UTAH WILL KEEP
LARGELY DRY CONDITIONS WITH LIGHTER WINDS.
HIGH TEMPERATURES THROUGH THE WEEK WILL BE IN THE LOW OR MID 90S FOR
VALLEYS, WHICH IS NEAR NORMAL FOR THE TIME OF YEAR.
AVIATION...KSLC
SCATTERED SHOWERS AND THUNDERSTORMS WILL
BE CAPABLE OF GUSTY, ERRATIC OUTFLOW WINDS FROM ROUGHLY 19-00Z.
SOUTH WINDS WILL PREVAIL, WITH GUSTS AROUND 20 KNOTS MUCH OF THE
AFTERNOON. REMNANT SHOWERS WILL BE CAPABLE OF TRANSITIONING WIND
DIRECTION AND INCREASING SPEEDS THROUGH ROUGHLY 05Z.
REST OF UTAH AND SOUTHWEST WYOMING
BROKEN TO OVERCAST CONDITIONS
WILL PREVAIL WITH SCATTERED AFTERNOON SHOWERS AND THUNDERSTORMS
THROUGHOUT SOUTHWEST WYOMING AND UTAH. THEY WILL BE CAPABLE OF
GUSTY, ERRATIC OUTFLOW WINDS AND LOCALLY HEAVY RAIN. SHOWERS AND
THUNDERSTORMS WILL TAPER OFF AFTER 00Z WITH DECREASING CLOUDS.
FIRE WEATHER
MONSOON MOISTURE WILL SPREAD NORTHWARD ACROSS THE
ENTIRE STATE TODAY, RESULTING IN INCREASED COVERAGE OF SHOWERS AND
THUNDERSTORMS ACROSS MUCH OF UTAH THIS AFTERNOON. ANY STORMS THAT
DEVELOP WILL BE CAPABLE OF PRODUCING WETTING RAINS. THE AIRMASS
OVER THE AREA WILL START TO DRY BEGINNING SATURDAY, WITH MORE
NOTICEABLE DRYING SUNDAY INTO MONDAY. BY MONDAY, WINDS WILL START
TO INCREASE AS A TROUGH MOVES ONSHORE ALONG THE PACIFIC NORTHWEST
COAST. THIS WILL BRING AN INCREASE IN SOUTHERLY WINDS ACROSS UTAH,
COMBINING WITH LOW HUMIDITIES EXPECTED OVER WESTERN UTAH TO BRING
A THREAT OF CRITICAL FIRE WEATHER CONDITIONS BOTH MONDAY AND
TUESDAY.
SLC WATCHES/WARNINGS/ADVISORIES
UT...NONE.
WY...NONE.
SHORT TERM/FIRE WEATHER...TRAPHAGAN
LONG TERM/AVIATION...WILSON
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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