FXUS66 KSTO 201140
AFDSAC

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 AM PST TUE JAN 20 2004

.DISCUSSION...
ETL PROFILERS AND ETA BUFKIT DATA SUGGEST TOPS OF STRATUS/STRATOCU 
DECK ABOUT 3000 FT IN THE VLY....AND PERHAPS UP TO 4000 FT IN THE 
SURROUNDING FTHLS. NWP GUIDANCE AND 00Z WS-ETA SFC RH PROGS SUGGEST 
THE VLY IN OUR CWA WILL BREAK OUT OF THE LOW CLOUDS TODAY. 
HOWEVER...DEPTH OF LOW CLOUDINESS AND TREND OF SLOWER TIMING OF THE 
SYNOPTIC PATTERN LEADS US TO BE MORE PESSIMISTIC FOR CLEARING OF THE 
LOW CLOUDS OVER THE SRN SAC AND NRN SJV VLY UNTIL LATE AFTN OR EARLY 
EVENING. SHORT WAVE CURRENTLY OVER NORCAL WILL BE DIVING SWD ACROSS 
THE CWA TODAY...WHILE A 2NDRY WAVE CURRENTLY NEAR THE ORG/WA BORDER 
SLIDES SWD ACROSS THE NE PLATEAU TODAY. SMALL AREA OF SHOWERS 
ASSOCIATED WITH THE FIRST WAVE WILL BE MOVING THRU ZONE 69 WITH MOST 
OF THE ACTIVITY REMAINING E OF THE CREST. RATHER MERIDIONAL SPEED 
MAX FORECAST TO BECOME MORE CYCLONIC TODAY AS THE SHORT WAVES DIVE 
SWD AND EVENTUALLY FORMS A CLOSED LOW OVER NRN BAJA AND OLD MEX 
EARLY THU. EARLIER MODEL RUNS INDICATED THE SPEED MAX WOULD BE S OF 
THE CWA BY 00Z WED...BUT CURRENT RUNS ARE ABOUT 6 HRS SLOWER...SO WE 
ARE LEANING TOWARD A SLOWER CLEARING SOLUTION FOR THE SRN PORTION OF 
THE CWA...AS THE STRONGER SUBSIDENCE WILL BE OVER THE NRN PORTION OF 
THE CWA. ALSO...DUE TO THE PRESSURE RISES OCCURING OVER ORG IN WAKE 
OF THE SHORT WAVE TODAY...THERE SHOULD BE ENOUGH NLY GRADIENT AND 
MIXING TO ERODE CLOUDS N OF THE SAC AREA...WITH SAC AREA CLEARING BY 
SUNSET...AND THE NRN SJV AREA CLEARING EARLY THIS EVENING AS THE NLY 
GRADIENT IS MORE RELAXED FARTHER S. MUST HAVE BEEN THE MIDNITE SHIFT 
MALAISE YESTERDAY...BUT THE FAILURE TO RECOGNIZE THAT THE SYNOPTIC 
PATTERN DID NOT LEND ITSELF TO CLEARING IN THE VLY YESTERDAY... 
UNLIKE TODAY...RESULTED IN A POOR FORECAST. AFTER A THOROUGH  
SELF-EXAM/CRITIQUE WE APOLOGIZE AND WILL TRY AGAIN TODAY. 

AS THE CLOSED LOW FORMS TO OUR S...THE FLOW ALOFT OVER NORCAL TURNS 
ANTICYCLONIC/OFFSHORE WED AND THU DUE TO A POSITIVELY-TILTED RIDGE  
BUILDING OVER NORCAL...AND SFC HIGH PRESSURE BUILDING INTO NV AND 
THE GREAT BASIN. THIS WILL INCREASE THE ELY GRADIENT...AND THE  
SAC-RNO GRADIENT WHICH IS +3 MBS NOW...WILL BECOME MINUS 6-8 MBS IN 
WAKE OF THE SHORT WAVES AND DEPARTING SPEED MAX TONIGHT. THIS WILL 
RESULT IN BREEZY/DOWNSLOPE CONDITIONS OVER THE SIERNEV AND BREEZY 
CONDITIONS OVER THE COASTAL RANGE. ONE BENEFIT IS THIS WILL ALSO 
LIMIT FOG IN THE VLY...THO WS-ETA AND BUFKIT SUGGEST THAT WINDS WILL 
BECOME LIGHT UNDER THE RADIATIVE INVERSION IN THE NRN SVJ AND VERY 
MOIST CONDITIONS IN THE LOW LEVELS WILL CAUSE STRATUS/FOG TO REFORM. 
IN THIS PATTERN...THERE USUALLY IS ENOUGH NLY GRADIENT TO KEEP LOW 
LEVELS MIXED ENOUGH IN THE SAC VLY TO PROHIBIT MUCH FOG. 

DOWNSLOPE/ADIABATIC WARMING SHOULD BE STRONGER WED THAN ON THU AS 
SFC HIGH SHIFTS EWD. THIS SHOULD OFFSET THE CAA FROM THE ELY FLOW ON 
WED...WHILE THE AIR MASS IS FORECAST TO MODIFYING SLIGHTLY ON THU. 
THIS SYNOPTIC PATTERN LENDS ITSELF TO LARGE DIURNAL TEMP RANGES IN 
THE BASINS/VALLEYS OF THE SIERNEV...AND COOL NIGHTS/MILD DAYS IN THE 
VALLEY AND LIMITED FOG. THIS PATTERN IS FORECAST TO BREAK DOWN AS 
EARLY AS FRI AND INTO THE WEEKEND AS A LONGER WAVE TROF DEEPENS OVER 
THE W...AND ENGERY PHASES INTO A CLOSED LOW OVER THE DESERT SW ON 
MON. THIS WILL RESULT IN A COOLER/UNSETTLED WX PATTERN.   JHM

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.STO WATCHES/WARNINGS/ADVISORIES...NONE.

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