FXUS65 KSLC 230437
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
937 PM MST TUE DEC 22 2009

.SYNOPSIS...A CLOSED UPPER LOW CENTERED OVER FAR SOUTHERN NEVADA
THIS EVENING AND WILL MOVE TO EASTERN ARIZONA BY WEDNESDAY MORNING
AS HIGH PRESSURE BUILDS INTO UTAH BEHIND IT. A SYSTEM MOVING SOUTH
ALONG THE CONTINENTAL DIVIDE WILL BRING A COLD NORTHERLY FLOW TO
THE AREA LATE WEDNESDAY THROUGH THURSDAY.

&&

.DISCUSSION...THE MID LEVEL FLOW ACROSS THE FORECAST AREA IS
SHIFTING TO NELY THIS EVE AND SNOW IS BEGINNING TO WIND DOWN
ACROSS THE NORTHWESTERN ZONES BUT HAS BEEN PICKING UP ACROSS THE
SOUTHWEST. THE SURFACE BOUNDARY IS SHIFTING INTO ERN UT AND SHOULD
EXIT THE CWA SHORTLY AFTER MIDNIGHT. 

ALTHO THE SNOW HAS BEEN DECREASING ACROSS THE NORTHWEST AS WELL AS
IN THE PRICE AREA...EXPECT AREAS OF LIGHT SNOW TO PERSIST FOR
SEVERAL MORE HOURS. WITH COLD TEMPS IN PLACE...THIS WILL CONTINUE
TO PRODUCE LIGHT ACCUMULATIONS THAT WILL IMPACT TRAVEL. SO WILL
LEAVE EXISTING HIGHLIGHTS UNCHANGED FOR NOW WITH THE IDEA THAT
THE NORTHERN ONES SHOULD BE ABLE TO BE DROPPED WITH THE EARLY
MORNING PACKAGE.

THE AZ LOW WILL SHIFT QUICKLY EAST OVERNIGHT THRU WED WHILE THE
NEXT COLD LOW CURRENTLY OVER WRN DROPS INTO THE NRN PLAINS. THE
COLD AIR WITH THIS FEATURE EXTENDS FAR ENOUGH W TO SPILL INTO UT
STARTING LATE WED AND CONTINUING THRU THU. THIS SHOULD BE A MOSTLY
DRY NORTHERLY FLOW BUT HAVE BEEN HANGING ONTO CONSIDERABLE
MOISTURE BELOW 700MB ACROSS WRN UT THRU THU. SO THERE COULD BE A
CONTINUED THREAT OF LIGHT SNOW FROM THIS INTO THU. 

THE NEW 00Z GFS NOW DEVELOPS A CLOSED HIGH OVER THE NRN ROCKIES
THIS WKND THAT KEEPS THE CWA DRY AND ONLY BRINGS A LITTLE MOISTURE
BACK INTO SRN UT NEXT MON FROM A CLOSED LOW THAT ENDS UP OFF THE W
COAST OF NRN BAJA. THIS IS PRETTY DIVERGENT FROM THE PREV RUN SO
CONFIDENCE IN FORECASTS PAST THIS WEEKEND ARE NEEDLESS TO SAY QUITE
LOW.

NO UPDATES PLANNED AT THIS TIME. 

&&

.AVIATION...CIGS EXPECTED TO BE PREVAILING MVFR AND VSBYS OCNLY
MVFR IN INTERMITTENT SNOW SHOWERS THROUGH AROUND 12Z.
HOWEVER...THERE IS A 20 PERCENT CHANCE THAT CONDITIONS COULD
BRIEFLY BECOME IFR IF SNOW SHOWERS BRIEFLY INTENSIFY THROUGH THE
SAME 12Z TIME PERIOD. CIGS ARE EXPECTED TO REMAIN BELOW 6000FT
THROUGH 16Z TO 18Z. NOT LOOKING FOR MUCH MORE THAN AN INCH OR TWO
OF ACCUMULATION TOTAL...BUT COLD SURFACE TEMPS WILL CONTINUE TO
SUPPORT ACCUMULATIONS ON NON- TREATED SURFACES.

&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 4 PM WEDNESDAY FOR UTZ517-UTZ518.

     WINTER STORM WARNING UNTIL 11 AM WEDNESDAY FOR UTZ005-UTZ014-
     UTZ015-UTZ016.

     WINTER WEATHER ADVISORY UNTIL 11 AM WEDNESDAY FOR UTZ003-UTZ004-
     UTZ011-UTZ012-UTZ013-UTZ020-UTZ021.

     WINTER WEATHER ADVISORY UNTIL 4 PM WEDNESDAY FOR UTZ008-UTZ009-
     UTZ010.

WY...NONE.

&&

$$

WILENSKY/HOSENFELD

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