120  
FXUS65 KSLC 211135  
AFDSLC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SALT LAKE CITY UT  
435 AM MST WED FEB 21 2018  
   
SYNOPSIS
 
AN ACTIVE WEATHER PATTERN WILL PREVAIL THROUGH THE  
NEXT 7 DAYS AS A SERIES OF WEATHER SYSTEMS MOVE THROUGH THE  
REGION.  
 

 
   
SHORT TERM (THROUGH 00Z SUNDAY)
 
A LONGWAVE TROUGH ENCOMPASSING  
THE WESTERN CONUS WILL REMAIN IN PLACE THROUGH THE SHORT TERM  
PERIOD, AS A SERIES OF SHORTWAVE FEATURES ROTATE THROUGH THE MEAN  
FLOW. THE NEXT WAVE TO IMPACT THE REGION IS DIGGING THROUGH THE  
WESTERN GREAT BASIN THIS MORNING, AND WILL SLOWLY TRANSLATE  
EASTWARD ACROSS THE FORECAST AREA TODAY THROUGH TONIGHT, WEAKENING  
AS IT DOES SO. WEAK MOISTURE ADVECTION AHEAD OF THIS WAVE TODAY  
FOLLOWED BY THE PASSAGE OF THE TROUGH AXIS TONIGHT MAY SQUEEZE OUT  
A FEW MOUNTAIN SNOW SHOWERS DURING THIS TIME, BUT OTHERWISE HAVE  
LITTLE REAL IMPACT ON THE FORECAST AREA.  
 
A MORE POTENT WAVE CURRENTLY DIGGING SOUTHWARD ALONG THE BRITISH  
COLUMBIA COASTLINE IS FORECAST TO DIG INTO THE GREAT BASIN  
THURSDAY, BEFORE SLOWLY MIGRATING EASTWARD ACROSS THE FORECAST  
AREA THURSDAY NIGHT INTO FRIDAY. THE GFS HAS TRENDED FURTHER NORTH  
WITH THE TRACK OF THIS WAVE OVER THE PAST 24 HOURS, HOWEVER IT  
STILL APPEARS CENTRAL AND SOUTHERN UTAH WILL SEE THE BRUNT OF  
ACCUMULATING SNOWFALL WITH THIS FEATURE. THIS WAVE IS EXPECTED TO  
QUICKLY MOVE EAST FRIDAY NIGHT, AS YET ANOTHER SHORTWAVE TROUGH  
APPROACHES THE REGION. LARGE SCALE ASCENT AHEAD OF THIS FEATURE  
WILL BRING A CHANCE OF SNOW TO THE HIGHER TERRAIN OF NORTHERN UTAH  
BEGINNING SATURDAY, AND HAVE INTRODUCED POPS ACCORDINGLY.  
 
   
LONG TERM (AFTER 00Z SUNDAY)
 
WITH THE LONGWAVE TROUGH  
PERSISTING OVER THE WESTERN CONUS, A SERIES OF SHORTWAVE TROUGHS  
CONTINUE TO PASS THROUGH THE INTERMOUNTAIN WEST THROUGH THE  
EXTENDED FORECAST. AS ONE SHORTWAVE IS EXITING SATURDAY, ANOTHER  
DROPS IN FROM THE PACIFIC NORTHWEST SATURDAY NIGHT INTO EARLY  
SUNDAY. HAVE INCREASED POPS THROUGH THIS PERIOD, AS AT LEAST A  
QUICK SHOT OF PRECIPITATION APPEARS LIKELY ACROSS THE NORTHERN  
HALF OF THE FORECAST AREA; THIS IS ESPECIALLY TRUE IN THE  
MOUNTAINS, WITH A (BRIEF) PERIOD OF MOIST UNSTABLE NORTHWEST FLOW  
DEVELOPING WITH THE TROUGH PASSAGE.  
 
THAT SAID, THIS TROUGH IS PROGRESSIVE AND FAST MOVING, WITH THE  
TROUGH AXIS ALREADY OVER COLORADO BY 00Z MONDAY. GOOD MIXING WITH  
THIS TROUGH WILL MAKE SATURDAY NIGHT/SUNDAY MORNING WARMER THAN  
THE PREVIOUS NIGHT, BUT DON'T EXPECT TOO MUCH IN THE WAY OF  
TEMPERATURE RELIEF, AS THE TROUGH ALSO REINFORCES THE COLD AIRMASS  
(-17C AT 700MB FOR MUCH OF THE STATE BY 18Z SUNDAY).  
 
SUNDAY NIGHT INTO MONDAY LARGELY LOOKS TO BE A BREAK IN THE  
ACTIVE WEATHER, AS THE SUNDAY TROUGH EXITS AND THE NEXT TROUGH IN  
THE TRAIN DIGS INTO CALIFORNIA. DETAILS BEGIN TO BREAK DOWN A BIT  
TUESDAY ONWARD, BUT IN GENERAL THE PATTERN LOOKS TO REMAIN COLD  
AND ACTIVE THROUGH THE WORK WEEK.  
 

 
   
AVIATION
 
WINDS AT THE SLC TERMINAL ARE EXPECTED TO SWITCH TO  
THE NORTHWEST AROUND 18-21Z, THOUGH THERE IS A 30 PERCENT CHANCE  
THAT WINDS REMAIN SOUTHEASTERLY PAST 21Z. CEILINGS MAY LOWER  
THROUGH THE DAY, BUT SHOULD REMAIN ABOVE 7000 FEET THROUGH AT  
LEAST 00Z.  
 

 
   
SLC WATCHES/WARNINGS/ADVISORIES
 
 
UT...NONE.  
WY...NONE.  

 
 

 
 
SEAMAN/SCHOENING  
 
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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