223 
FXUS65 KSLC 111714
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
1013 AM MST FRI JAN 11 2013

.SYNOPSIS...THE COLD UPPER LEVEL TROUGH WILL MOVE SLOWLY EAST
ACROSS UTAH TODAY. A COLD AND MOIST NORTHERLY FLOW ALOFT WILL
REMAIN OVER THE AREA THROUGH SATURDAY...FOLLOWED BY A DRIER AND
MORE STABLE AIRMASS LATE IN THE WEEKEND THROUGH EARLY NEXT WEEK.

&&

.DISCUSSION...A BROAD COLD UPPER TROUGH WILL MAINTAIN ITS WINTRY 
GRIP ON THE EASTERN GREAT BASIN INTO THE WEEKEND. THE LOW CENTER 
WILL BE WORKING ITS WAY ACROSS NORTHERN UTAH TODAY WHILE COLDER AIR 
ALOFT WILL CONTINUE TO SPREAD INTO THE AREA THROUGH THE MORNING 
HOURS. AS THE AIRMASS BECOMES INCREASINGLY UNSTABLE...SNOW WILL FILL 
IN ACROSS THE AREA ONCE AGAIN AND CONTINUE AT TIMES THROUGH THE 
NIGHT. ALTHOUGH SNOW WILL LIKELY BECOME FAIRLY WIDESPREAD ACROSS 
NORTHERN AND CENTRAL UTAH ONCE AGAIN...BENCHES AND WEST-FACING 
SLOPES OF NORTHERN AND CENTRAL UTAH WILL SEE THE BRUNT OF THE NEW 
ACCUMULATION. GIVEN THE COLD AIRMASS...ENHANCEMENT OF SNOW EAST AND 
SOUTHEAST OF THE GREAT SALT LAKE WILL LIKELY LEAD TO LOCALLY 
ENHANCED TOTALS AS WELL.

EMBEDDED DISTURBANCES ROTATING AROUND THE MEAN TROUGH WILL CONTINUE 
TO BRING PERIODS OF SNOW TO THE AREA INTO SUNDAY. HOWEVER...THE 
AIRMASS WILL BECOME INCREASINGLY COLD...WITH 700MB TEMPERATURES OF 
-18C AT SLC THIS MORNING EXPECTED TO LOWER TO NEAR -21C ON SUNDAY. 
AS A RESULT...MANY AREAS WILL FAIL TO EVEN REACH MAX TEMPERATURES OF 
20 DEGREES OVER THE WEEKEND. AS THE STORM EXITS THE AREA...IT WILL 
BE REPLACED BY A STRONG UPPER RIDGE THAT WILL SETTLE OVER THE WEST 
COAST. THE RESULTING STABLE AIRMASS WILL SERVE TO STRENGTHEN VALLEY 
INVERSIONS...ESPECIALLY WITH AMPLE SNOW COVER EXISTING THROUGHOUT 
THE AREA. THUS...EXPECT MUCH OF NEXT WEEK WILL BE DOMINATED BY COLD 
VALLEY TEMPERATURES AND DECREASING AIR QUALITY.

WILL UPDATE MAINLY TO REDUCE POP/SKY ACROSS THE SOUTH FOR THE 
REMAINDER OF THE MORNING. WILL ALSO CONSIDER DROPPING WINTER WEATHER 
HIGHLIGHTS FOR CASTLE COUNTRY AND THE SANPETE/SEVIER VALLEYS LATER 
THIS MORNING.

&&

.AVIATION...ATMOSPHERE REMAINS MOIST AND UNSTABLE WHICH WILL KEEP 
THE THREAT OF SNOW OR SNOW SHOWERS GOING THROUGH THE SLC TAF PERIOD. 
PRIMARY FORECAST UNCERTAINTY RESTS WITH TIMING AND LOCATION OF LAKE 
EFFECT SNOW BANDS WHICH WILL PRODUCE LIFR CONDITIONS WHERE THEY 
PERSIST.  EXPECT MOST INTENSE LAKE EFFECT ACTIVITY TO BE NORTH OF 
SLC THIS MORNING...POSSIBLY SHIFTING SOUTHWARD ACROSS THE SLC 
TERMINAL THIS AFTERNOON OR EVENING. 

ADDITIONAL ACCUMULATIONS OF ONE TO TWO INCHES POSSIBLE FROM 
EARLY THIS AFTERNOON THROUGH LATE EVENING.

WINDS ARE EXPECTED TO BE WEST SOUTHWEST THROUGH THIS AFTERNOON AND 
EVENING WITH A 30 PERCENT CHANCE OF GOING NORTHWEST AFTER 2200 WITH 
INCREASED SNOW SHOWER ACTIVITY.


&&

.SLC WATCHES/WARNINGS/ADVISORIES...
UT...WINTER STORM WARNING UNTIL 6 PM MST SATURDAY FOR 
     UTZ007>010-517-518. 

     WINTER STORM WARNING UNTIL NOON MST SATURDAY FOR UTZ006. 

     WINTER STORM WARNING UNTIL NOON MST SATURDAY FOR UTZ005-014>016. 

     WINTER STORM WARNING UNTIL NOON MST SATURDAY FOR UTZ001>004. 

     WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR UTZ012. 

WY...WINTER WEATHER ADVISORY UNTIL NOON MST SATURDAY FOR WYZ021. 

&&

$$

CHENG/STRUTHWOLF

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

FOR FREQUENTLY ASKED QUESTIONS ABOUT THE AREA FORECAST DISCUSSION
VISIT...
HTTP://WEATHER.GOV/SALTLAKECITY/GENERAL/AFD_FAQS.PHP (ALL LOWER CASE)