666
FXUS65 KSLC 210418
AFDSLC
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1018 PM MDT THU AUG 20 2026
KEY MESSAGES
- HOT TEMPERATURES WILL PERSIST OVER THE VALLEYS OF NORTHERN UTAH
FRIDAY, WITH LOW TEMPERATURES IN THE MID TO UPPER 70S PROVIDING
LITTLE OVERNIGHT RECOVERY.
- MONSOONAL MOISTURE WILL SURGE INTO UTAH AND SOUTHWEST WYOMING
FRIDAY AND SATURDAY, PERSISTING THROUGH AT LEAST EARLY NEXT
WEEK. THIS WILL BRING AN INCREASED THREAT OF SHOWERS AND
THUNDERSTORMS CAPABLE OF PRODUCING HEAVY RAIN THAT COULD LEAD TO
FLASH FLOODING.
DISCUSSION
HIGH PRESSURE IS CENTERING ITSELF OVER THE FOUR
CORNERS REGION THIS EVENING, WITH A SOUTHERLY FLOW DEVELOPING OVER
UTAH AND SOUTHWEST WYOMING. DESPITE SOME DRYING OVER THE PAST
COUPLE OF DAYS, SATELLITE DERIVED PW VALUES ARE STILL
PREDOMINATELY IN THE 0.7 TO 0.8 INCH RANGE, MORE THAN ENOUGH FOR
DEVELOPMENT OF SHOWERS AND THUNDERSTORMS OVER THE HIGHER TERRAIN
THIS AFTERNOON, WITH CONVECTIVE ACTIVITY CONTINUING OVER SOUTHERN
UTAH, INCLUDING A FEW STRONG THUNDERSTORMS SHORT RANGE GUIDANCE IS
INDICATING THAT SHORTWAVE ENERGY MOVING IN FROM ARIZONA SHOULD
KEEP SOME SHOWERS AND THUNDERSTORMS GOING THROUGH THE FIRST PART
OF THE OVERNIGHT HOURS, WITH COVERAGE DIMINISHING AS SUNRISE
APPROACHES.
TEMPERATURES WERE QUITE HOT ACROSS THE VALLEYS OF NORTHERN UTAH
THIS AFTERNOON, WITH MOST VALLEYS SEEING TEMPERATURES AROUND 100F.
LOWS IN THE LOWER TO MID 70S WILL NOT PROVIDE MUCH IN THE WAY OF
RELIEF, WITH HIGHS IN THIS AREA TOMORROW EXPECTED TO BE SIMILAR TO
TODAY. GOING HEAT ADVISORY COVERS THIS THREAT WELL.
THE SOUTHERLY FLOW THAT IS DEVELOPING WILL ALLOW MONSOON MOISTURE
TO SPREAD INTO CENTRAL AND SOUTHERN UTAH DURING THE DAY FRIDAY AND
INTO NORTHERN PORTIONS OF THE AREA FRIDAY EVENING INTO SATURDAY
MORNING. AS A RESULT, COVERAGE OF CONVECTION WILL BE MORE
WIDESPREAD TOMORROW AFTERNOON, BUT GIVEN THE LACK OF ADDITIONAL
FORCING MECHANISMS INITIALLY, SHOULD BE FOCUSED OVER THE HIGHER
TERRAIN AT FIRST. SEEING EVIDENCE THAT SOME MORE SHORTWAVE ENERGY
FROM ARIZONA WILL EJECT NORTHWARD DURING THE LATE AFTERNOON,
IMPACTING NORTHERN UTAH DURING THE EVENING, POTENTIALLY BRINGING
ADDITIONAL CONVECTION TO THE VALLEYS OF NORTHERN UTAH.
ONCE THE MOISTURE IS IN PLACE, THERE IS LITTLE CHANGE IN THE
PATTERN EXPECTED THROUGH EARLY NEXT WEEK AS CONFIDENCE IS HIGH
THAT THE RIDGE WILL CONTINUE TO PARK ITSELF OVER THE FOUR CORNERS.
THIS WILL BRING HIGH TEMPERATURES NEAR SEASONAL NORMALS BY THE
START OF THE UPCOMING WEEK, WITH A DAILY THREAT OF SHOWERS AND
THUNDERSTORMS THAT COULD PRODUCE HEAVY RAIN CAPABLE OF FLASH
FLOODING, PARTICULARLY DURING THE AFTERNOON AND EARLY EVENING. AS
THE MIDDLE OF NEXT WEEK APPROACHES, CONFIDENCE IN THE PATTERN
DECREASES NOTICEABLY, WITH A GOOD PORTION OF GUIDANCE SHOWING A
DRYING TREND FROM THE WEST AS THE RIDGE RETROGRADES OVER ARIZONA.
AVIATION...KSLC
THE SLC TERMINAL WILL SEE VFR CONDITIONS
THROUGH THE OVERNIGHT HOURS WITH SOME SCATTERED CLOUDS. SOUTHERLY
WINDS WILL CONTINUE OVERNIGHT BEFORE SHIFTING TO THE NORTH BETWEEN
19Z AND 21Z. WITH INCREASING MOISTURE, THERE IS A 30 PERCENT
CHANCE OF THE TERMINAL SEEING A PERIOD OF GUSTY AND ERRATIC
THUNDERSTORM WINDS FRIDAY, WITH THE MOST LIKELY TIME DURING THE
LATE AFTERNOON AND EARLY EVENING.
REST OF UTAH AND SOUTHWEST WYOMING...VFR CONDITIONS WILL PREVAIL
ACROSS THE AIRSPACE THROUGH THE OVERNIGHT HOURS. SCATTERED SHOWERS
AND THUNDERSTORMS OVER SOUTHERN UTAH ARE EXPECTED TO PERSIST INTO
THE OVERNIGHT HOURS BEFORE DIMINISHING AS SUNRISE APPROACHES. ANY
STORMS THAT DEVELOP WILL HAVE THE POTENTIAL TO PRODUCE GUSTY AND
ERRATIC WINDS, LIGHTNING, AND BRIEF MOUNTAIN OBSCURATIONS. WITH
MOISTURE INCREASING TOMORROW, COVERAGE OF SHOWERS AND
THUNDERSTORMS WILL BECOME A BIT MORE WIDESPREAD TOMORROW
AFTERNOON, WITH SIMILAR POTENTIAL AVIATION IMPACTS AS TODAY. AWAY
FROM THUNDERSTORMS, GENERALLY LIGHT AND TERRAIN DRIVEN WINDS WILL
PREVAIL.
FIRE WEATHER, ISSUED 136 PM MDT THU AUG 20 2026
MONSOONAL MOISTURE IS EXPECTED TO INCREASE ACROSS UTAH
THROUGH THE WEEKEND, BRINGING INCREASED COVERAGE OF SHOWERS AND
THUNDERSTORMS ACROSS THE HIGH TERRAIN IN THE REGION. IN ADDITION
TO SHOWER AND THUNDERSTORM ACTIVITY, A TREND OF INCREASING
HUMIDITY IS EXPECTED AREAWIDE. THAT SAID, LOWER ELEVATIONS OF
WESTERN, EASTERN, AND SOUTHERN UTAH WILL CONTINUE TO SEE MINIMUM
RELATIVE HUMIDITY VALUES IN THE MID- TO UPPER-TEENS. FOR THE
HIGHER TERRAIN AREAS, MINIMUM VALUES MAY ONLY FALL INTO THE 25 TO
35 PERCENT RANGE WITH GOOD TO EXCELLENT RECOVERY EXPECTED
AREAWIDE. WHILE PROBABILITY FOR WETTING RAINS WILL BE RELATIVELY
HIGH OVER THE MOUNTAINOUS TERRAIN (UP TO 45-60 PERCENT CHANCE),
LOWER LYING ADJACENT VALLEY AREAS WILL SEE FAR LOWER CHANCES (15
PERCENT OR LESS). ON FRIDAY IN PARTICULAR, DEVELOPING STORMS WILL
BRING POTENTIAL FOR STRONG OUTFLOW WINDS OVER CENTRAL AND NORTHERN
UTAH. DAILY SHOWER AND THUNDERSTORM CHANCES WILL BE MAINTAINED THROUGH
AT LEAST TUESDAY NEXT WEEK, WITH STORMS EXPECTED TO DEVELOP OVER THE
HIGH TERRAIN FEATURES EACH AFTERNOON.
SLC WATCHES/WARNINGS/ADVISORIES
UT...HEAT ADVISORY UNTIL 7 AM MDT SATURDAY FOR UTZ101>106.
HEAT ADVISORY UNTIL 7 AM MDT FRIDAY FOR UTZ115-116.
WY...NONE.
PUBLIC...TRAPHAGAN
AVIATION...TRAPHAGAN
FIRE WEATHER...WEBBER
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY
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