FXUS65 KSLC 081143
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
443 AM MST TUE DEC 8 2009

.SYNOPSIS..A STORM SYSTEM WILL MOVE EAST OUT OF THE AREA BY THIS 
EVENING. A VERY COLD WEST TO NORTHWEST FLOW ALOFT WILL DEVELOP 
MIDWEEK...PRODUCING BITTERLY COLD TEMPERATURES THROUGH THE END OF 
THE WEEK.

&&

.DISCUSSION...AN UPPER LEVEL TROUGH CURRENTLY CENTERED OVER EASTERN 
UTAH WILL CONTINUE TO MOVE EAST TODAY. MSAS ANALYSIS SHOWS A DEEP 
SURFACE LOW WITH MSLP OF 985MB NEAR THE FOUR CORNERS AREA THIS 
MORNING. THIS STRONG STORM HAS RESULTED IN WIDESPREAD HEAVY SNOW 
ACROSS MUCH OF THE AREA YESTERDAY AND OVERNIGHT...ESPECIALLY ACROSS 
SOUTHERN AND CENTRAL UTAH. WITH THE PASSAGE OF THE TROUGH 
AXIS...NORTHWESTERLY FLOW ALOFT HAS NOW DEVELOPED ACROSS MUCH OF 
UTAH. 

PRECIPITATION FILLED IN OVER NORTHERN UTAH OVERNIGHT AS COLD 
ADVECTION DEVELOPED OVER THE AREA AND THIS CONTINUES CURRENTLY ALONG 
THE WASATCH FRONT AND MOUNTAINS. DUE TO THE SNOWFALL ALONG THE 
WASATCH FRONT...HAVE ISSUED A WINTER WEATHER ADVISORY FOR THE 
NORTHERN WASATCH FRONT AND UPGRADED TO A WINTER STORM WARNING FOR 
THE SALT LAKE VALLEY. REASONING BEHIND THIS IS BECAUSE COLD SURFACE 
TEMPERATURES WILL ALLOW SNOW TO RAPIDLY ACCUMULATE ON AREA 
ROADWAYS...RESULTING IN A HAZARDOUS COMMUTE. FURTHERMORE...LOW 
DENSITY SNOW WILL RESULT IN HIGH ACCUMULATIONS DESPITE LOW WATER 
CONTENT...AND THIS IS CORROBORATED BY REPORTS OF SIGNIFICANT 
SNOWFALL ACROSS THE NORTHWEST DESERTS OVERNIGHT. SNOW MAY BE 
ENHANCED DURING THE AFTERNOON BY THE GREAT SALT LAKE IMPACTING 
MAINLY AREAS WEST OF THE LAKE. 

OTHERWISE...SNOW WILL CONTINUE TO FILL IN ALONG THE CENTRAL AND 
SOUTHERN MOUNTAINS AND OTHER UPSLOPE REGIONS THIS 
MORNING...PARTICULARLY THE I-15 CORRIDOR BEFORE GRADUALLY TAPERING 
OFF DURING THE DAY. ACROSS SOUTH-CENTRAL AND EASTERN UTAH...SNOW IS 
ONGOING AND SUSPECT THAT IT WILL NOT END WHEN THE ORIGINAL WARNING 
EXPIRES AT 6AM...SO HAVE EXTENDED THESE THROUGH 10AM. BUT WITH 
NORTHWEST FLOW BECOMING ESTABLISHED OVER THE REGION...SNOW SHOULD 
QUICKLY TAPER OFF ACROSS THE EASTERN ZONES BY MID-MORNING. WILL 
LIKELY ALLOW THE WARNING FOR UTAHS DIXIE TO EXPIRE AT 6AM. ALL OTHER 
HEADLINES HAVE BEEN LEFT UNCHANGED.

THE STORM SYSTEM MOVES OUT OF THE AREA THIS EVENING...BUT WARM 
ADVECTION WILL DEVELOP ACROSS THE NORTH TOMORROW. THIS WILL RESULT IN
LINGERING PRECIPITATION MAY CONTINUE ACROSS THE FAR NORTH THROUGH 
TOMORROW. ALTHOUGH MOUNTAINS WILL GRADUALLY WARM THROUGH LATE 
WEEK...EXPECT VALLEY TEMPERATURES TO REMAIN QUITE COLD DUE TO SNOW 
COVER AND THE COLD AIR FROM THIS STORM THAT WILL BECOME TRAPPED IN 
THE VALLEYS.

MODELS ARE STILL WORKING OUT THE DETAILS FOR THE EXTENDED 
PERIOD...BUT A SERIES OF WEAK BUT MOIST SYSTEMS LOOK TO IMPACT THE 
AREA FRIDAY AND AGAIN OVER THE WEEKEND.

&&

.AVIATION...SNOW IS EXPECTED TO CONTINUE AT THE SLC TERMINAL THROUGH 
THE MORNING WITH PREDOMINATELY IFR CONDITIONS. SNOW SHOWERS ARE 
LIKELY THIS AFTERNOON...RESULTING IN LOW-END MVFR TO HIGH-END IFR 
CONDITIONS. WINDS WILL REMAIN OUT OF THE NORTHWEST THROUGHOUT THE 
DAY.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 4 PM TODAY FOR 
     UTZ003-UTZ008-UTZ009-UTZ010-UTZ517-UTZ518.

     WINTER STORM WARNING UNTIL NOON TODAY FOR UTZ014-UTZ015-UTZ016.

     WINTER STORM WARNING UNTIL 6 AM TODAY FOR UTZ019.

     WINTER WEATHER ADVISORY UNTIL 4 PM TODAY FOR 
     UTZ002-UTZ004-UTZ006.

WY...NONE.

&&

$$

PUBLIC...CHENG
AVIATION...TRAPHAGAN

FOR MORE INFORMATION FROM NOAA/S NATIONAL WEATHER SERVICE VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY (ALL LOWER CASE)