208  
FXUS65 KSLC 172144  
AFDSLC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SALT LAKE CITY UT  
344 PM MDT SUN JUN 17 2018  
   
SYNOPSIS
 
A LOW PRESSURE SYSTEM CURRENTLY OVER THE PACIFIC  
NORTHWEST WILL SETTLE INTO THE REGION AND BRING COOLER  
TEMPERATURES AND PERIODS OF UNSETTLED CONDITIONS TO THE NORTHERN  
PORTION OF UTAH EARLY NEXT WEEK.  
 

 
   
SHORT TERM (THROUGH 00Z THURSDAY)
 
AS THE UPPER LEVEL LOW  
ROTATES THROUGH NEVADA THIS AFTERNOON BECOMING MORE POSITIVELY  
TILTED, THE AREA OF GREATEST DIFFLUENCE AND BEST INSTABILITY  
REMAINS IN THE FAR NORTHERN AREA OF UTAH AND SOUTHERN WYOMING.  
WIND SHEAR IS MAXIMIZED ACROSS THIS AREA WITH 30-40 KT OF SHEAR  
AND A SMALLER AREA OF 45+ KTS. PRECIPITABLE WATER IS ELEVATED  
HOWEVER NOT AS MUCH AS WAS SEEN YESTERDAY, WITH THE DECAYING  
TROPICAL MOISTURE FURTHER DRYING OUT ACROSS THE ROCKIES. RADAR HAS  
BECOME ACTIVE THIS AFTERNOON FROM NEAR SCOFIELD NORTHWARD INTO  
SOUTHERN IDAHO AND SOUTHERN WYOMING. EXPECTING STORMS TO DIE DOWN  
BETWEEN 04Z AND 06Z THIS EVENING.  
 
WHILE THE STORMS THIS AFTERNOON ARE MOVING RATHER QUICKLY, THE  
DEEP MIXING AND STRONG DIVERGENCE ALOFT IS PROVIDING A GOOD  
ENVIRONMENT FOR RAPID GROWING STORM DEVELOPMENT. UTILIZING SOME  
LOCAL TOOLS AND STUDIES, THE ENVIRONMENT SEEMS CONDUCIVE TO SMALL  
HAIL AND STRONG WINDS WITH STORMS THAT DEVELOP.  
 
AS THE UPPER LOW CONTINUES TO LIFT THROUGH THE AREA MONDAY, THE  
FAVORABLE AREA FOR CONVECTION REMAINS ACROSS THE NORTH WITH THE  
PLACEMENT OF THE LOW. SOUTHERLY WINDS WILL CONTINUE TO FILTER IN  
DRIER CONDITIONS FROM THE SOUTH WHILE WINDS WILL BEGIN TO TREND  
DOWN. CONDITIONS ACROSS THE SOUTH WILL REMAIN ON THE DRY AND  
BREEZY SIDE THROUGH MONDAY, KEEPING THE CONCERN FOR ELEVATED  
CRITICAL FIRE WEATHER CONDITIONS IN FOCUS.  
 
MODELS HAVE THE LOW LIFTING OUT OF THE FORECAST AREA BY LATE  
MONDAY INTO TUESDAY WITH HIGH PRESSURE BUILDING IN ACROSS THE  
WEST, NAMELY THE SOUTHWEST U.S. AREA. TEMPERATURES WILL REMAIN  
NEAR SEASONAL NORMAL GOING INTO MID WEEK WITH UNSETTLED CONDITIONS  
POSSIBLE ACROSS THE NORTH, HOWEVER LESSENING EACH DAY.  
   
LONG TERM (AFTER 00Z THURSDAY)
 
HIGH PRESSURE CENTERED OVER  
NORTHWEST MEXICO IS EXPECTED TO BUILD BACK OVER THE FORECAST AREA  
WEDNESDAY NIGHT INTO THURSDAY, RESULTING IN A DRYING AND WARMING  
TREND. MAXES ARE EXPECTED TO RISE TO VALUES 5-7F ABOVE SEASONAL  
NORMALS BY THURSDAY AFTERNOON.  
 
EC/GFS SHOW THE RIDGE WEAKENING FRIDAY AS AN ILL-DEFINED TROUGH  
MOVES OVER THE TOP OF IT. WITH LITTLE MOISTURE IN ASSOCIATION WITH  
IT, NOT EXPECTING MUCH IN THE WAY OF PRECIP BUT IT WILL BRING IN  
SOME COOLER AIR FOR NORTHERN UTAH, BRINGING MAXES BACK DOWN TO NEAR  
SEASONAL NORMALS WHILE SOUTHERN UTAH STAYS WARM.  
 
LATEST GFS BRINGS A BETTER DEFINED LOW ACROSS NORTHERN UTAH ON  
SATURDAY, RESULTING IN CONTINUED COOLING. EC SHOWS HIGH PRESSURE  
MOVING BACK IN DURING THIS TIME, AND THEREFORE INDICATES 700MB TEMPS  
ABOUT 5C HIGHER THAN THE GFS. FOR NOW, HAVE MAINTAINED PERSISTENCE  
FOR TEMPERATURES GOING INTO SUNDAY.  
 

 
   
AVIATION
 
VFR CONDITIONS ARE EXPECTED THROUGH THE EVENING AT THE  
SLC TERMINAL. GUSTY SOUTHERLY WINDS ARE EXPECTED TO CONTINUE THROUGH  
THE EVENING BEFORE SHIFTING TO THE NORTHWEST WITH A COLD FRONT, MOST  
LIKELY BETWEEN 05Z AND 07Z. NEARBY SHOWERS MAY RESULT IN PERIODS OF  
GUSTY AND/OR ERRATIC WINDS EARLY THIS EVENING.  
 

 
   
FIRE WEATHER
 
PERSISTENT GUSTY SOUTHWEST WINDS WILL CONTINUE INTO  
LATE THIS EVENING ACROSS THE AREA AND ESPECIALLY THE SOUTH. DRY  
CONDITIONS IN PLACE ACROSS THE SOUTH WILL LEAD TO CRITICAL FIRE  
WEATHER CONDITIONS THROUGH THIS EVENING. AS THE UPPER LEVEL LOW  
SLOWLY MOVES EAST AND NORTH STARTING MONDAY, WINDS WILL BEGIN TO  
RELAX AND A GRADUAL COOLING OF TEMPERATURES AND SLIGHT INCREASE IN  
RH VALUES SHOULD LOWER THE CRITICAL FIRE WEATHER THREAT. INCREASED  
WINDS ALOFT TODAY THROUGH TUESDAY ARE PROVIDING EXCELLENT MIXING  
AND VENTILATION ACROSS THE AREA. THE WEATHER PATTERN WILL REMAIN  
UNSETTLED ACROSS THE NORTHERN PORTIONS OF THE DISTRICT AS THE LOW  
SLOWLY EXITS THE AREA BY MID WEEK WITH HIGH PRESSURE PUSHING IN  
FROM THE WEST.  
 

 
   
SLC WATCHES/WARNINGS/ADVISORIES
 
 
UT...RED FLAG WARNING UNTIL 10 PM MDT THIS EVENING FOR UTZ494-495-497-  
498.  
 
WY...NONE.  

 
 

 
 
SHORT TERM/FIRE WEATHER...DEWEY  
LONG TERM/AVIATION...TRAPHAGAN  
 
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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