FXUS65 KSLC 252241
AFDSLC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SALT LAKE CITY UT
340 PM MST FRI DEC 25 2009

.SYNOPSIS...A COLD NORTHERLY FLOW WILL CONTINUE ACROSS UTAH THROUGH 
EARLY SATURDAY. A SERIES OF WEAK DISTURBANCES WILL MOVE ACROSS THE 
GREAT BASIN THROUGH MUCH OF NEXT WEEK. 

&&

.DISCUSSION...A HIGH AMPLITUDE RIDGE CONTINUES TO BUILD OVER THE 
WEST COAST THIS AFTERNOON WHILE A LARGE CLOSED LOW REMAINS CENTERED 
OVER THE UPPER MIDWEST. JET STREAK DIVING DOWN THE BACKSIDE OF THE 
LOW INTO WESTERN UTAH BROUGHT SOME CLOUDS TO NORTHEAST UTAH AND 
SOUTHWEST WYOMING WITH LIGHT SNOW/FLURRIES IN THE HIGHER ELEVATIONS. 
OCCASIONAL CLOUDS AND LIGHT SNOW WILL CONTINUE TO SPREAD INTO THE 
AREA FROM THE NORTHEAST THROUGH TONIGHT BEFORE THE LOW SHIFTS EAST 
OUT OF THE AREA. 

FOG DEVELOPMENT WILL BE A POSSIBILITY TONIGHT...BUT THE AIRMASS 
APPEARS DRY ENOUGH THAT MOST PRONE VALLEYS WILL ONLY SEE PATCHY 
COVERAGE AT BEST. IN ADDITION...NORTHEAST UTAH VALLEYS COULD SEE FOG 
DEVELOPMENT SOMEWHAT HAMPERED BY THE PASSING CLOUDS. THE MAIN AREA 
TO WATCH WHERE FOG IS CONCERNED WILL BE THE SANPETE AND SEVIER 
VALLEYS WHICH COULD SEE A REPEAT OF LAST NIGHTS DENSE FOG EPISODE 
DUE TO MOSTLY CLEAR SKIES AND AN AIRMASS WHICH REMAINS NEARLY 
SATURATED AT THE SURFACE.

THE RIDGE WILL GET PINCHED OFF THIS WEEKEND WITH A CLOSED UPPER HIGH 
OVER ALBERTA AND NEAR ZONAL FLOW DEVELOPING OVER SOUTHERN UTAH AND 
ARIZONA. VERY WEAK DISTURBANCES WILL CROSS THE AREA IN THIS FLOW 
SUNDAY AND MONDAY. HOWEVER...MOISTURE AND DYNAMICS WILL BE RATHER 
LIMITED WITH THESE WAVES...SO ANY PRECIPITATION THAT DOES MANAGE TO 
FALL WILL BE LIGHT. HAVE KEPT POPS LOW FOR THIS PERIOD AS A RESULT.

MODEL DIFFERENCES STILL EXIST FOR THE MIDWEEK PERIOD. THE GFS 
CONTINUES TO SUGGEST A SHORTWAVE TROUGH WILL MOVE ACROSS 
UTAH...SPREADING PRECIPITATION TO MUCH OF THE AREA ON WEDNESDAY. THE 
EC IS WEAKER AND A BIT FARTHER NORTH WITH THIS DISTURBANCE...SO IN 
THIS SCENARIO MUCH OF THE AREA WILL BE DRIER. CONFIDENCE IS STILL 
TOO LOW AT THIS TIME TO BRING POPS MUCH ABOVE CLIMO. A BROADER AREA 
OF HIGH PRESSURE WILL SETTLE ACROSS THE REGION FOR THE LATTER PART 
OF NEXT WEEK.

&&

.AVIATION...MAIN CONCERN AT KSLC OVERNIGHT IS FOG POTENTIAL. CURRENT 
THINKING IS THERE IS ROUGHLY A 20 PERCENT CHANCE OF DENSE FOG AFTER 
08Z. MID AND HIGH LEVEL MOISTURE ROTATING WEST ACROSS WY SHOULD 
REACH NORTHERN UT AND SUFFICIENTLY DISRUPT RADIATIONAL COOLING TO 
LIMIT FOG POTENTIAL. OTHERWISE ANTICIPATE PREDOMINANT VFR CONDITIONS 
THROUGH THE PERIOD. 

&&

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

WY...NONE.

&&

$$

PUBLIC...CHENG
AVIATION...SEAMAN

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