SFOAFDSTO (11/22/08 0955)

FXUS66 KSTO 221758 AAA
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
930 AM PST SAT NOV 22 2008

.DISCUSSION...
DENSE FOG HAS PLAGUED PORTIONS OF SACRAMENTO...SAN 
JOAQUIN...SOLANO...YUBA...SUTTER AND YOLO COUNTIES THIS MORNING. 
VISIBILITIES REMAIN AT 1/4 MILE AT SAC INTERNATIONAL...STOCKTON AND 
SAC EXECUTIVE. ON THE VISIBLE SATELLITE LOOP IT APPEARS THE FOG IS 
BEGINNING TO ERODE IN SAN JOAQUIN COUNTY THIS PAST HOUR...FARTHER 
NORTH THE VISIBILITY HAS IMPROVED TO OVER 1 MILE AT KMYV. LIFTING IS 
ALSO BEGINNING TO DEVELOP IN SOLANO TO SACRAMENTO COUNTY AS VERTICAL 
TURRETS APPEAR VISIBLE. WILL ALLOW THE DENSE FOG PRODUCT TO EXPIRE 
AT 10 AM. LOCALLY DENSE FOG WILL PROBABLY PERSIST FOR ANOTHER HOUR 
OR SO AND WILL COVER THIS WITH NOWCASTS. 

SYNOPTIC PATTERN FEATURES A FLAT FLOW ACROSS THE EASTERN PACIFIC. A 
WEAK SHORTWAVE TROF IS MOVING THROUGH NORTHERN CALIFORNIA AND 
SOUTHERN OREGON THIS MORNING. A SURFACE COLD FRONT CAN BE SEEN 
STRETCHING NORTH OF UKIAH TO THE MT. SHASTA AND KLAMATH FALLS AREA. 
EXTENSIVE BKN-OVC LAYER NEAR 5000 FEET OBSERVED FROM ALTURAS TO 
SISKIYOU THOUGH CLOUDS ARE THINNING BEHIND THE FRONT. MT. SHASTA AND 
KLMT HAD A LIGHT MIX OF RAIN AND SNOW EARLIER. DO NOT BELIEVE THESE 
WILL AFFECT SHASTA COUNTY AT ALL. LOCALLY DENSE FOG IS ALSO 
IMPACTING HIGHER MOUNTAIN VALLEYS LIKE CHESTER AND QUINCY THIS 
MORNING. 

TROF MOVES THROUGH TODAY...BRINGING ABOUT 5 DEGREES OF COOLING TO 
NORTHERN AREAS AND ELEVATIONS ABOVE 5000 FEET. SACRAMENTO AND 
STOCKTON WILL HAVE ABOUT THE SAME TEMPERATURES AS YESTERDAY....AS 
WILL VALLEJO AND FAIRFIELD. UNDER CLEARING SKIES TONIGHT...FOG MAY 
BE AN ISSUE AGAIN. FORECAST SOUNDINGS DO NOT INDICATE AS MOIST A 
BOUNDARY LAYER OVERNIGHT IN A WEAK NORTHERLY BREEZE ALONG THE WEST 
SIDE OF THE VALLEY. HOWEVER...THIS MAY SERVE TO CAUSE DENSE FOG 
ALONG THE EAST SIDE OF THE VALLEY. 

IN THE CENTRAL PACIFIC...A 170 KT JET WILL CARVE OUT AN UPPER LOW 
ABOUT 500 MILES WEST OF SAN FRANCISCO BY SUNDAY NIGHT. 
DOWNSTREAM...THIS MEANS UPPER RIDGING FOR CALIFORNIA. EXPECT 
TOMORROW'S WEATHER TO BE VERY SIMILAR TO TODAY...PERHAPS SEVERAL 
DEGREES WARMER IN THE MOUNTAINS AS THE FLOW BACKS TO THE SOUTH AHEAD 
OF THE AFOREMENTIONED UPPER TROF. WILL ANALYZE THIS TROF AND IT'S 
POTENTIAL IMPACT ON CALIFORNIA IN THE AFTERNOON PACKAGE. SG

&&

.AVIATION...
VFR CONDITIONS AND LIGHT WINDS WILL BE PREVALENT OVER MOST OF THE 
AREA FOR THE NEXT 24 HOURS. MVFR VSBYS WITH LOCALIZED LIFR 
VSBYS/CIGS IN FOG WILL PREVAIL IN THE CENTRAL VALLEY SOUTH OF THE 
SUTTER BUTTES AND IN MOUNTAIN VALLEYS THROUGH MIDDAY TODAY. ISOLATED 
SHOWERS WILL MOVE THROUGH THE NORTHERN MOUNTAINS THIS MORNING AS A 
WEAK COLD FRONT PASSES THROUGH. EXPECT IFR TO LIFR FOG TO REDEVELOP 
OVERNIGHT TONIGHT. 

&&

.STO WATCHES/WARNINGS/ADVISORIES...DENSE FOG ADVISORY FOR THE 
SOUTHERN SACRAMENTO AND NORTHERN SAN JOAQUIN VALLEYS TILL 10 AM PST 
SATURDAY. 

&&