FXUS65 KSLC 091152
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
450 AM MST WED DEC 9 2009

.SYNOPSIS...A VERY COLD AIRMASS WILL REMAIN IN PLACE THROUGH LATE 
THIS WEEK UNDER A WEST TO NORTHWEST FLOW. A SERIES OF MOIST PACIFIC 
STORM SYSTEMS WILL IMPACT THE AREA OVER THE WEEKEND.

&&

.DISCUSSION...A WEAK SHORTWAVE DISTURBANCE IS CURRENTLY NOTED ON 
WATER VAPOR IMAGERY PASSING OVER THE EASTERN GREAT BASIN. ALTHOUGH 
IT IS ASSOCIATED WITH ONLY WEAK DYNAMICS...IT IS ENOUGH TO KEEP SOME 
CLOUDS AND LIGHT SNOW ACROSS PORTIONS OF NORTHEAST UTAH AND 
SOUTHWEST WYOMING OVERNIGHT. THIS IS EXPECTED TO CONTINUE THROUGH 
EARLY THIS EVENING...BUT ANY ACCUMULATIONS WILL BE VERY LIGHT. GUSTY 
WINDS EXPECTED ACROSS SOUTHWEST WYOMING AND THE HIGHER PEAKS OF 
NORTHERN UTAH TODAY COULD RESULT IN REDUCED VISIBILITIES IN BLOWING 
SNOW AND MAY IMPACT TRAVEL ALONG PORTIONS OF INTERSTATE-80. 
OTHERWISE...MAIN STORY FROM OVERNIGHT HAS BEEN THE VERY COLD 
TEMPERATURES WITH MOST AREAS ACROSS UTAH SEEING TEMPERATURES NEAR TO 
BELOW ZERO. THIS COLD START TO THE DAY WILL HELP KEEP HIGH 
TEMPERATURES 15 TO 25 DEGREES BELOW NORMAL ACROSS MOST AREAS.

OTHERWISE...A NORTHWESTERLY TO WESTERLY FLOW ALOFT WILL REMAIN OVER 
THE AREA THROUGH THE LATTER PART OF THE WEEK. ALTHOUGH WARM 
ADVECTION AT 700MB DEVELOPS TODAY...THIS WILL ONLY SERVE TO 
STRENGTHEN VALLEY INVERSIONS. THUS...EXPECT A VERY SLOW WARMING 
TREND FOR VALLEY AREAS WITH MANY LOCATIONS ACROSS NORTHERN AND 
CENTRAL UTAH REMAINING BELOW FREEZING. 

A SERIES OF WEAK BUT MOIST PACIFIC SHORTWAVE TROUGHS WILL MOVE 
ACROSS THE AREA LATE FRIDAY THROUGH THE WEEKEND. THIS WILL AGAIN 
BRING WIDESPREAD PRECIPITATION TO THE AREA...BUT TEMPERATURES WILL 
BE WARMER THAN THIS LAST STORM. THE TIMING OF EACH INDIVIDUAL 
FEATURE REMAINS A BIT DIFFICULT AT THIS TIME...BUT SUFFICE TO SAY 
THAT PRECIPITATION WILL OCCUR OFF AND ON OVER MANY AREAS DURING THE 
WEEKEND. HAVE LEFT POPS IN THE CHANCE TO LIKELY RANGE FOR THIS 
PERIOD. WILL PROBABLY SEE SOME P-TYPE ISSUES THIS WEEKEND WITH 700MB 
TEMPERATURES IN THE -6 TO -8C RANGE. LATEST GFS SUGGESTS THAT SOUTH 
WINDS WILL INCREASE ON SATURDAY...SO WILL HAVE TO SEE HOW WELL THE 
VALLEYS MIX. 

A DIRTY RIDGE IS EXPECTED TO BUILD OVER THE REGION FOR THE EARLY 
PART OF NEXT WEEK. THIS COULD KEEP CLOUDS ACROSS NORTHERN UTAH...BUT 
AT THIS TIME MODELS SUGGEST THAT PRECIPITATION WILL MAINLY STAY TO 
THE NORTH ACROSS IDAHO.

&&

.AVIATION...THE SLC TERMINAL WILL SEE VFR CONDITIONS THROUGHOUT THE 
DAY. SOUTHEAST WINDS ARE EXPECTED TO SHIFT TO THE NORTHWEST BETWEEN 
17Z AND 19Z...BUT THERE IS A 30 PERCENT CHANCE THIS SHIFT WILL BE 
DELAYED OR WILL NOT OCCUR AT ALL. CIGS NEAR 6000FT AGL THIS MORNING 
ARE EXPECTED TO ERODE BY EARLY AFTERNOON.

&&

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

&&

$$

PUBLIC...CHENG
AVIATION...TRAPHAGAN

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