559  
FXUS65 KSLC 301618  
AFDSLC  
 
AREA FORECAST DISCUSSION  
NATIONAL WEATHER SERVICE SALT LAKE CITY UT  
1017 AM MDT THU MAR 30 2017  
   
SYNOPSIS
 
AN UPPER LOW WILL DEVELOP ACROSS THE GREAT BASIN  
TODAY, THEN SLOWLY DRIFT EAST ALONG THE UTAH ARIZONA BORDER  
TONIGHT THROUGH FRIDAY. HIGH PRESSURE WILL RETURN SATURDAY,  
FOLLOWED BY ANOTHER COLD FRONT EARLY NEXT WEEK.  
 

 
   
DISCUSSION
 
THE UPSTREAM TROUGH IS CURRENTLY EVIDENT ON SATELLITE  
IMAGERY DIVING SOUTH OVER CALIFORNIA AND IS ACCOMPANIED BY A POTENT  
COLD FRONT WHICH IS CURRENTLY CROSSING CENTRAL NEVADA. AHEAD OF THIS  
STORM, PRECIPITATION HAS DEVELOPED ACROSS NORTHERN UTAH GIVEN A  
COMBINATION OF INCREASING UPPER DIFFLUENCE, COOLING ALOFT, AND WARM  
TEMPERATURES AT 700MB. SNOW LEVELS REMAIN HIGH WITH THIS INITIAL  
ROUND OF PRECIPITATION WITH 700MB TEMPERATURE REMAINING IN THE -1 TO  
-2C RANGE. DUAL-POL DATA AND BRIGHT BANDING ON KMTX SUPPORT SNOW  
LEVELS AROUND 7500FT. THIS PREFRONTAL PRECIPITATION WILL CONTINUE  
SPREADING INTO SOUTHWEST WYOMING, THROUGH THE UINTAS, AND INTO  
CASTLE COUNTRY LATE THIS MORNING INTO THIS AFTERNOON.  
 
WINDS WILL INCREASE AHEAD OF THE FRONT, STRONGEST ACROSS SOUTHERN  
UTAH. A WIND ADVISORY REMAINS IN PLACE ALONG THE ARIZONA BORDER.  
CONSIDERED ADDING THE SOUTHWEST UTAH ZONE WHICH INCLUDES CEDAR CITY  
AND MILFORD, BUT DURATION WILL BE SHORTER AND INCREASING CLOUD COVER  
AND PRECIPITATION THROUGH THE AFTERNOON HOURS MAY HINDER MIXING.  
 
THE TROUGH WILL PINCH OFF INTO A CLOSED LOW OVER NEVADA AND AS IT  
DOES SO, THE COLD FRONT WILL SLOW AND THEN WEAKEN OVER UTAH THIS  
AFTERNOON AND EVENING. AN INITIAL LOOK AT THE 12Z GFS SHOWS THE  
FRONT MAKING SLIGHTLY LESS EASTWARD PROGRESS OVER UTAH. STILL,  
ENOUGH OF A SURFACE GRADIENT WILL EXIST TO BRING SOME GUSTY  
POSTFRONTAL WINDS TO THE WESTERN UTAH VALLEYS. A WIND ADVISORY  
REMAINS IN PLACE FOR THESE POSTFRONTAL WINDS ACROSS NORTHWEST UTAH.  
 
PRECIPITATION WILL INCREASE ACROSS WESTERN UTAH ALONG THE BOUNDARY  
THIS AFTERNOON. THIS WILL BE WIDESPREAD AND LOCALLY HEAVY AT TIMES  
AND MAY CONTAIN EMBEDDED THUNDERSTORMS. WITH THE LOW CENTER THEN  
TRACKING ACROSS SOUTHERN UTAH TONIGHT INTO TOMORROW, MOISTURE  
WRAPPING AROUND THE LOW WILL FAVOR SOUTHERN AND PORTIONS OF EASTERN  
UTAH AS WELL AS SOUTHWEST WYOMING, BUT IN PARTICULAR THE I-15  
CORRIDOR ACROSS SOUTHWEST UTAH AND ADJACENT MOUNTAINS. THE COLDEST  
AIR WILL BE NEAR THE LOW CENTER ACROSS SOUTHERN UTAH, AND LOOKS TO  
FALL INTO THE 4500-5500FT RANGE. VARIOUS GOING WINTER WEATHER  
HIGHLIGHTS COVER AREAS OF CONCERN.  
 
EASTERLY FLOW ACROSS NORTHERN UTAH DEVELOPING TONIGHT AND MAXING OUT  
TOMORROW NIGHT INTO SATURDAY MORNING IS STILL WORTH WATCHING.  
CURRENTLY, THE SURFACE GRADIENT DOES NOT APPEAR TO BE ESPECIALLY  
TIGHT, AND ALTHOUGH 700MB WINDS ARE FORECAST TO REACH 50KT ACROSS  
NORTHEAST UTAH AND SOUTHWEST WYOMING, THE LACK OF ANY DECENT COLD  
ADVECTION EXCEPT FOR A PERIOD FRIDAY NIGHT INTO EARLY SATURDAY  
MORNING SUGGEST THE LIKELIHOOD FOR A SIGNIFICANT WIND EVENT IS NOT  
VERY HIGH AT THIS TIME. THAT BEING SAID, LOCAL GUSTY WINDS ARE STILL  
EXPECTED, ESPECIALLY NEAR CANYONS.  
 
NO UPDATES THIS MORNING.  
 

 
   
AVIATION
 
SHOWERS WILL BE MOVING IN THE VICINITY OF THE SLC  
TERMINAL AT TIMES THIS MORNING, THE MAIN IMPACT OF THESE BEING  
OCCASIONAL PERIODS OF ERRATIC WINDS AND CEILINGS DROPPING BELOW 7K  
FEET. OUTSIDE OF THESE SHOWERS VFR CONDITIONS AND AT TIMES STRONG  
SOUTHERLY WINDS WILL PREVAIL UNTIL FRONTAL PASSAGE AROUND 22-23Z.  
FROPA SHOULD BRING A PERIOD OF MVFR RAIN AND A WIND SHIFT TO THE  
NORTHWEST.  
 

 
   
SLC WATCHES/WARNINGS/ADVISORIES
 
 
UT...WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 9 PM MDT THIS EVENING  
FOR UTZ019>021.  
 
WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 AM MDT SATURDAY  
FOR UTZ009-015-016-517-518.  
 
WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 6 AM MDT  
SATURDAY FOR UTZ007-008-010-014.  
 
WIND ADVISORY FROM 2 PM THIS AFTERNOON TO 4 AM MDT FRIDAY FOR  
UTZ005.  
 
WY...WINTER WEATHER ADVISORY FROM 3 AM FRIDAY TO 6 AM MDT SATURDAY  
FOR WYZ021.  
 

 
 

 
 
CHENG/CARR  
 
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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