770  
FXUS65 KSLC 162233  
AFDSLC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SALT LAKE CITY UT  
433 PM MDT MON SEP 16 2019  
   
SYNOPSIS
 
A STRONG COLD FRONT WILL SWEEP SOUTHEAST ACROSS THE  
NORTHERN UTAH THIS EVENING, THEN WEAKEN AS IT MOVES INTO SOUTHERN  
UTAH LATE TONIGHT THROUGH TUESDAY. MUCH COOLER TEMPERATURES WILL  
TRAIL THE COLD FRONT, FOLLOWED BY A BRIEF WARMUP MIDWEEK AHEAD OF  
THE NEXT STORM SYSTEM ARRIVING LATE IN THE WEEK.  
 

 
   
SHORT TERM (UNTIL 00Z FRIDAY)
 
THE UPPER TROUGH WITH AN EMBEDDED  
VORTICITY MAX ALONG THE OREGON/CALIFORNIA BORDER WILL CONTINUE  
EAST AND GRADUALLY WEAKEN AS IT CROSSES THE GREAT BASIN THROUGH  
EARLY TUESDAY. THE ASSOCIATED SURFACE FRONT WILL REMAIN FAIRLY  
STRONG AS IT MOVES OUT OF NEVADA AND INTO NORTHWEST UTAH THIS  
EVENING. THIS FRONT WILL WEAKEN AS IT WORK INTO CENTRAL/SOUTHERN  
UTAH LATER TONIGHT.  
 
THE MAIN ISSUE TONIGHT WILL BE THE WIND ASSOCIATED WITH THE COLD  
FRONT. THIS COLD FRONT SUPPORTED BY THE FAIRLY STRONG NEAR 700MB  
SOUTHWEST WINDS HAS GENERATED STRONG SOUTHERLY WINDS ACROSS MUCH  
OF WESTERN UTAH THIS AFTERNOON. THESE WINDS IN THE PRE-FRONTAL  
ENVIRONMENT WILL REMAIN ELEVATED EARLY THIS EVENING, THEN SWITCH  
TO THE WEST AND REMAIN ELEVATED ACROSS FAR NORTHWEST UTAH TROUGH  
LATE EVENING. PERSISTENT LOW-LEVEL COLD ADVECTION WILL KEEP WINDS  
ELEVATED ACROSS THE FAR NORTH OVERNIGHT. LACK OF THERMAL SUPPORT  
FARTHER TO THE SOUTH WILL RESULT IN DECREASING WINDS BEHIND THE  
FRONT THROUGH CENTRAL/SOUTHERN UTAH AFTER MIDNIGHT.  
 
CONVECTIVE PRECIP LOOKS TO REMAIN LIMITED IN INTENSITY AND AREAL  
COVERAGE AS THE AFOREMENTIONED VORTICITY MAX TRACKS EAST THROUGH  
THE WESTERN/NORTHERN GREAT BASIN THROUGH EARLY TUESDAY. IN UTAH  
THE BEST CHANCE FOR CONVECTION WILL COME BEHIND THE SURFACE FRONT  
AND WILL CONCENTRATED NEAR THE VORTICITY MAX EMBEDDED IN THE MID-  
LEVEL COLD POOL ALONG THE UTAH/IDAHO BORDER.  
 
A DRY/STABLE AIR MASS AND MUCH COOLER TEMPERATURES TRAILING THE  
COLD FRONT WILL BRING FALL-LIKE CONDITIONS TO THE AREA TUESDAY.  
A NEW AND COLDER UPPER TROUGH ADVANCING SOUTH ALONG THE BRITCOL  
COAST WILL SETTLE INTO THE PACIFIC NORTHWEST BY EARLY WEDNESDAY.  
BACKING FLOW ACROSS THE GREAT BASIN AHEAD OF THIS FEATURE WILL  
BRING WARMER AND WINDIER CONDITIONS BACK INTO UTAH WEDNESDAY.  
THE COLD FRONT ASSOCIATED WITH THIS SECOND TROUGH WILL REACH  
FAR NORTHWEST UTAH LATE WEDNESDAY, THEN SLOWLY WORK EAST AS THE  
UPPER TROUGH ADVANCES THROUGH THE WESTERN GREAT BASIN/NORTHERN  
ROCKIES THROUGH THURSDAY.  
 
AREAS EAST OF THIS SURFACE BOUNDARY WILL REMAIN WINDY AND WARM  
THROUGH THURSDAY AFTERNOON. BEHIND THE FRONT MUCH COOLER  
TEMPERATURES WILL RETURN, WITH PRECIP REMAINING CLOSE TO THE  
STRONGEST LIFT AND COLD AIR ALOFT WITH THE TROUGH OVER NORTHWEST  
UTAH AND POINTS NORTH AND WEST.  
   
LONG TERM (AFTER 00Z FRIDAY)
 
THE DEEPENING POSITIVELY TILTED  
TROUGH SWINGS THROUGH THE GREAT BASIN LATE THURSDAY INTO FRIDAY  
BRINING ANOTHER ROUND OF GUSTY PRE-FRONTAL WINDS AND PRECIPITATION  
ALONG WITH COLDER TEMPERATURES. THIS SYSTEM DIGS A BIT FARTHER SOUTH  
THAN THE PREVIOUS ONE AND HAS SOME COLDER AIR ASSOCIATED WITH IT.  
THE FRONTAL PASSAGE LOOKS TO BE LATE DAY/EVENING TIMING, SIMILAR TO  
THIS PAST TROUGH PASSAGE, BUT SHOULD HAVE SOME WEAKER WINDS BEHIND  
IT.  
 
AS THE COLD CORE MOVES OVER NORTHERN UTAH FRIDAY THE BEST ENERGY  
WILL BE LINED UP WITH PRECIPITATION TIMING. THIS COULD RESULT IN  
SHOWERY CONDITIONS ACROSS NORTHERN UTAH FRIDAY MORNING THROUGH  
AFTERNOON. MODELS, BOTH DETERMINISTIC AND ENSEMBLES HAVE A GOOD  
HANDLE ON THIS SYSTEM AND ARE THANKFULLY ALL IN AGREEMENT WITH ONE  
ANOTHER LARGELY. SOME VARIANCES OVER THE LAST FEW RUNS, BUT OVERALL  
THE TREND IS COMING TOGETHER MUCH BETTER. AS THE WEATHER SYSTEM  
LIFTS TO THE NORTHEAST BY SATURDAY, RISING HEIGHTS AND WARMING  
TEMPERATURES WILL SLOWLY BUILD BACK IN FROM THE WEST.  
 

 
   
AVIATION
 
SOUTHERLY WINDS WILL CONTINUE TO INCREASE THROUGH THE  
MORNING AT THE SLC TERMINAL. WIND GUSTS ARE EXPECTED TO NEAR TO  
EXCEED 35KTS AFTER 19Z. A STRONG COLD FRONT WILL CROSS THE TERMINAL  
BETWEEN 03-06Z TONIGHT...BRINGING A SIGNIFICANT WIND SHIFT TO THE  
NORTHWEST.  
 

 
   
FIRE WEATHER
 
THE UPPER TROUGH OVER THE WEST COAST STATES LATE  
THE AFTERNOON WILL WEAKEN AS IT MOVES EAST ACROSS UTAH LATER  
TONIGHT THROUGH EARLY TUESDAY. THE ASSOCIATED COLD FRONT WILL  
REMAIN STRONG AS IT ENTERS UTAH THIS EVENING, WITH STRONG  
SOUTHERLY WINDS AHEAD OF THE FRONT AND GUSTY NORTHWEST WINDS  
BEHIND THE FRONT THIS EVENING. MUCH COOLER TEMPERATURES WILL  
FOLLOW THE FRONT FOR TUESDAY.  
 
THE NEXT STORM SYSTEM WILL MOVE INTO THE PACIFIC NORTHWEST BY  
EARLY WEDNESDAY, THEN WORK SLOWLY EAST ACROSS THE NORTHERN  
ROCKIES AND GREAT BASIN LATE IN THE WEEK. WINDY AND WARM  
CONDITIONS WILL DEVELOP AHEAD OF THIS STORM WEDNESDAY AND  
THURSDAY, WITH PRECIPITATION AND COOLER AIR MOVING INTO THE  
STATE BY LATE THURSDAY AND FRIDAY.  
 

 
   
SLC WATCHES/WARNINGS/ADVISORIES
 
 
UT...RED FLAG WARNING UNTIL 4 AM MDT TUESDAY FOR UTZ478-482-489-  
492>498.  
 
WIND ADVISORY UNTIL 4 AM MDT TUESDAY FOR UTZ001>004-006-014>016-  
019.  
 
HIGH WIND WARNING UNTIL 4 AM MDT TUESDAY FOR UTZ005.  
 
WY...NONE.  

 
 

 
 
CONGER/DEWEY  
 
FOR MORE INFORMATION FROM NOAA'S NATIONAL WEATHER SERVICE VISIT...  
HTTP://WEATHER.GOV/SALTLAKECITY  
 
FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION  
VISIT...  
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP  
 
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