798  
FNUS75 KSLC 232201  
FWSSLC  
 
SPOT FORECAST FOR BIG MOUNTAIN...NUIFC  
NATIONAL WEATHER SERVICE SALT LAKE CITY UT  
401 PM MDT SUN AUG 23 2026  
 
FORECAST IS BASED ON FORECAST START TIME OF 1600 MDT ON AUGUST 23.  
IF CONDITIONS BECOME UNREPRESENTATIVE...CONTACT THE NATIONAL WEATHER  
SERVICE.  
   
DISCUSSION  
A DRY SOUTHWESTERLY FLOW WILL CONTINUE TO MIX DOWN  
THROUGH THE REMAINDER OF THE AFTERNOON AND EARLY EVENING RESULTING  
IN GUSTY WINDS. SHOWERS AND THUNDERSTORMS WELL TO THE WEST OF THE  
FIRE WILL GRADUALLY SPREAD EAST OVER THE NEXT FEW HOURS. MOST OF  
THESE WILL REMAIN NORTH OF THE FIRE, HOWEVER THERE IS A 30% CHANCE  
THESE STORMS PASS NEAR OR OVER THE FIRE AREA DURING THE 1800-2200  
WINDOW. LIGHTNING, STRONG OUTFLOW WINDS IN EXCESS OF 40 MPH, AND  
HEAVY RAIN ARE ALL POSSIBLE WITH THESE STORMS SHOULD THEY IMPACT  
THE FIRE THIS EVENING. BY LATE EVENING WINDS WILL BECOME TERRAIN  
DRIVEN AS THE NIGHTTIME INVERSION BEGINS TO SET UP. A SIMILAR  
PATTERN IS EXPECTED MONDAY, WITH GUSTY SOUTHWEST WINDS SURFACING  
BY EARLY AFTERNOON, AND A FEW LATE AFTERNOON AND EVENING SHOWERS  
AND THUNDERSTORMS POSSIBLE.  
 
   
REST OF TODAY (THROUGH 1800 HOURS)  
 
SKY/WEATHER.........MOSTLY SUNNY (10-20 PERCENT CLOUD COVER).  
CWR.................0 PERCENT.  
CHANCE OF PCPN......10 PERCENT.  
CHANCE OF LIGHTNING.6 PERCENT.  
MAX TEMPERATURE.....AROUND 90.  
MIN HUMIDITY........16-19 PERCENT.  
WIND (20 FT)........SOUTHWEST 5-10 MPH WITH GUSTS 18-24 MPH.  
MIXING HEIGHT.......12800 FT AGL (80-90TH PERCENTILE).  
TRANSPORT WINDS.....SOUTHWEST AROUND 20 MPH.  
   
TONIGHT (1800-0600)  
 
SKY/WEATHER.........PARTLY CLOUDY (45-60 PERCENT CLOUD COVER). A  
CHANCE OF SHOWERS AND THUNDERSTORMS IN THE  
EVENING, THEN A SLIGHT CHANCE OF SHOWERS  
OVERNIGHT.  
CWR.................5 PERCENT.  
CHANCE OF PCPN......30 PERCENT.  
CHANCE OF LIGHTNING.20 PERCENT.  
MIN TEMPERATURE.....65-68.  
MAX HUMIDITY........41-45 PERCENT.  
WIND (20 FT)........SOUTHWEST 5-9 MPH WITH GUSTS TO 10 MPH EARLY,  
BECOMING DOWNSLOPE/DOWN-DRAINAGE 3-7 MPH  
AFTER 2000. GUSTY AND ERRATIC OUTFLOW WINDS  
THUNDERSTORMS IN THE EVENING.  
MIXING HEIGHT.......12100 FT AGL DECREASING TO 500 FT AGL  
OVERNIGHT.  
TRANSPORT WINDS.....SOUTHWEST AROUND 15 MPH BECOMING SOUTH AROUND  
5 MPH OVERNIGHT.  
   
MONDAY  
 
SKY/WEATHER.........MOSTLY SUNNY (20-30 PERCENT CLOUD COVER),  
BECOMING PARTLY CLOUDY WITH A SLIGHT CHANCE  
OF SHOWERS AFTER 1500.  
CWR.................0 PERCENT.  
CHANCE OF PCPN......15 PERCENT.  
CHANCE OF LIGHTNING.10 PERCENT.  
MAX TEMPERATURE.....AROUND 90.  
MIN HUMIDITY........16-20 PERCENT.  
WIND (20 FT)........SOUTHWEST WINDS 6 TO 9 MPH.  
MIXING HEIGHT.......12900 FT AGL (80-90TH PERCENTILE).  
TRANSPORT WINDS.....SOUTHWEST 15 MPH.  
 
 
FORECASTER...SEAMAN  
REQUESTED BY...CASEY HANSEN  
TYPE OF REQUEST...WILDFIRE  
.TAG 2620325.0/SLC  
.DELDT 08/23/26  
.FORMATTERVERSION 2.0.0  
.EMAIL UTNUC@FIRENET.GOV,NATET@UTAHCOUNTY.GOV  
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