Severe Thunderstorm Warning 6, NWS Sacramento, CA

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE SACRAMENTO CA
205 PM PST SUN MAR 16 2003

UPDATE AT 330 PM...MESO LOW LEE SIDE OF SOUTHERN COASTAL RANGE HAS
FORMED AS FORECAST BY THE ETA. THIS AREA IS QUITE UNSTABLE. METARS
SHOWING SE FLOW 10-15 MPH FEEDING INTO WEST SIDE SOUTHERN SAC VALLEY
TO DELTA. NW STEERING FLOW IS ALSO INITIATING STORMS IN THE
LOWER COASTAL RANGE NEAR VACAVILLE AND SENDING THEM SOUTH ACROSS THE
DELTA INTO THE SJ VALLEY. LARGE HAIL PRIMARY THREAT BUT STRONG
ROTATION NOTED ON THE COLUSA CELL THAT PROMPTED A TORNADO WARNING.
LAPS CAPE IS MAX 1000 J/KG IN THIS STORM AND RIGHT IN THE HEART OF
THE MESO LOW AND SURFACE CONVERGENCE MAX. VIL HAS PEAKED TO 32.

ACTIVE CONVECTIVE AFTERNOON AGAIN IN OUR FORECAST AREA. FRONTAL BAND
NOW MOVING INTO CENTRAL SJ VALLEY AND YOSEMITE. SECONDARY SURFACE
MOISTURE CONVERGENCE AREA SUPPORTING SLOW MOVING LINE OF HEAVY
SHOWERS THAT FORMED IN LAKE COUNTY IS NOW A LINE OF SHOWERS AND
THUNDERSTORMS FROM THE STRAIT NORTHEAST ACROSS SOUTHERN SAC COUNTY TO THE
MOTHERLODE SOUTH OF I-80. HEAVY RAIN OCCURRED AT SMF WITH .55 INCHES
IN ABOUT AN HOUR OR LESS (TOTAL 3-DAY NEAR 3 INCHES FOR SMF). RAIN
RATES REPORTED UP TO .50 TO .75 INCHES PER HOUR IN THE STRAIT VERIFYING
THE .50 TO .80 ESTIMATED ON WSR-88D 1-H PRECIP. NLDN DEPICTING MAX 7
STRIKES PER 15 MINUTES. SEVERAL REPORTS OF PEA TO MARBLE SIZE HAIL
IN THE CARQUINEZ STRAIT. 88D VILS OF NEAR 20 MAX AND POSH 50 SO FAR.
MANY NOWCASTS (NOWSTO) BEEN WRITTEN FOR ACTIVITY. SVSSTO SENT OUT
FOR 2 REPORTS OF A FUNNEL CLOUD NEAR SUISUN EARLIER. TO THE NORTH
WHERE MUCAPE IS MUCH HIGHER DUE TO PARTIAL CLEARING THERE ARE
SCATTERED THUNDERSTORMS ON THE COASTAL FOOTHILLS MOVING SLOWLY IN
WEAK STEERING FLOW INTO THE VALLEY. STRONGEST CELL WE ISSUED WARNING
FOR VIL 30 AND POSH 90. WEAK HELICITY ON PROFILES SO MAIN CONCERN IS
HAIL THREAT WITH COLD AIR MASS ALOFT (-9C AT 700MB) AND SECONDARY
CONCERNS LOCALLY HEAVY RAIN AND FUNNEL CLOUDS. MOIST CONVECTION BAND
SHOULD CONTINUE TO SLOWLY RIDE UP THE WEST SLOPE OF THE SIERRA
NEVADA LATER TODAY INTO EARLY EVENING. STEERING FLOW TURNING MORE NW
BEHIND MAY AREA OF CONVECTION.

12Z GFS CONTINUES TO BE SLIGHTLY FASTER...STRONGER (SUCH AS H85-7
OMEGA) AND FURTHER NORTH WITH THE OMEGA FIELD PLACING IT OVER THE
SOUTHERN 2/3 OF OUR FORECAST AREA ALONG THE MAIN FRONTAL BANDS
EASTWARD MOVEMENT. BY LATE AFTERNOON BOTH MODELS SIMILAR WITH DEEPER
MOISTURE ALONG THE EAST SIDE IN -2 TO -8 H7 OMEGA FIELD WHILE H85
OMEGA AND NEARLY SATURATED LAYER LINGERS OVER THE EAST SIDE VALLEY
INTO THE MOTHERLODE. GFS H85 OMEGA FIELD MATCHING RIGHT ON WITH THE
ORGANIZED AREA OF CONVECTION PER RADAR TRENDS IN SOUTHERN ZONES.
SNOW LEVELS RUNNING FROM 3500-4000 FT IN THE NORTH TO NEAR 4500 FT
ON I-80 WILL REMAIN NEAR THESE LEVELS. ONLY LIGHT SNOW HAS BEEN
OCCURRING OVER THE SIERRA NEVADA BUT EXPECTED VALLEY PRECIP TO
DELIVER A COUPLE INCHES LATER TODAY. TURNS OUT THE SLOWER ETA OF
YESTERDAY IS WORKING BETTER FOR THIS REGION. PRECIPITATION WILL
CONTINUE OVER THE EAST SIDE OF THE VALLEY INTO THE SIERRA NEVADA
THIS EVENING AS BOTH GFS AND ETA LINGER H7 OMEGA IN THIS AREA BEFORE
ENDING. VALLEY CONVECTION WILL DIMINISH NEAR SUNSET WITH WEAK
SUBSIDENCE/QVEC DIVERENCE DEVELOPING AND LOW LEVEL STABILIZATION. NOTED 18Z
GFS AND ETA SHOW AREA OF H7 OMEGA IN NW FLOW AND HIGH RH MOVING OVER
NORTHERN SIERRA NEVADA AND SOUTHERN CASCADES LATE TONIGHT SO WILL
LEAVE SNOW SHOWER WORDING THOSE ZONES INTO MONDAY.

NEXT WAVE WILL DROP SOUTH OF THE REGION TONIGHT AS THE UPPER JET
SAGS SOUTHWARD PLACING INCREASING SUBSIDENCE AND NORTHERLY FLOW OVER
NORCAL ON MONDAY. ONLY PRECIP ON MONDAY WILL BE A FEW IF ANY LIGHT
SHOWERS OVER THE SIERRA CREST. NORTHERLY FLOW SURFACE AND ALOFT
UNDER SUBSIDENCE WILL PROVIDE DRY WEATHER INTO TUESDAY. AIR MASS
WARMS SIGNIFICANTLY AND VALLEY TEMPS SHOULD RISE INTO THE 60S WILL
VERY GOOD MIXING.

12Z GFS AND UKMET HAVING SIMILAR SLIGHTLY NEGATIVE TILTED TROF
PUSHING A COLD FRONT INTO NORCAL WEDNESDAY EVENING AND THROUGH THE
REGION THURSDAY. ENSEMBLE MEMBERS SHOW GOOD AGREEMENT ON THURSDAY.
THE UPPER LEVEL SYSTEM SPLITS SOME ON THURSDAY AS IT ENCOUNTER THE
REX BLOCK OVER THE MID WEST. SO THE FRONT WILL WEAKEN BUT BE QUITE
STRONG WHEN IT HITS THE COAST AND BEGINS TO MOVE INLAND. WE HAVE
RAISED POPS THIS DAY. PRECIP TURNING TO SCATTERED SHOWERS THURSDAY
AFTERNOON AND MAYBE A THUNDERSTORM.

FURTHER OUT UPPER RIDGING DEVELOPS FRIDAY AND CONTINUES INTO SATURDAY AS
THE TROF DIGS TO OUR SE. STORM TRACK REMAINS NORTH OF THE REGION
NEXT WEEKEND BUT FAR NORCAL MAY GET BRUSHED BY PASSING SYSTEMS.

THANKS TO SPOTTERS MIKE AND BILL FOR CHASING STORMS TODAY.

.STO...NONE

KBBX RADAR IS CURRENTLY DOWN.

BLU BU 027/039 032/047 034 65910
RBL BU 042/063 040/066 042 654-0
SAC BU 041/064 040/065 043 655-0

TARDY

CAZ013>019-063-064-066>069-171500-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SACRAMENTO CA
700 AM PST SUN MAR 16 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...TODAY

THE AIRMASS WILL BE UNSTABLE AGAIN ACROSS THE SOUTHERN VALLEY AREAS
THIS AFTERNOON WHICH COULD TRIGGER ISOLATED THUNDERSTORMS ACROSS
PORTIONS OF THE SACRAMENTO AND NORTHERN SAN JOAQUIN VALLEYS.

THE SNOW ADVISORY FOR THE MOUNTAINS OF SHASTA COUNTY HAS BEEN
CANCELLED.  ADDITIONAL SNOWFALL ACCUMULATIONS IN THE AREA ARE NOT
EXPECTED TO BE MORE THAN A COUPLE OF INCHES. REFER TO THE WINTER
WEATHER MESSAGE (WWUS46 KSTO WSWSTO) FOR DETAILS.

.DAYS TWO THROUGH SEVEN

NO HAZARDOUS WEATHER EXPECTED AT THIS TIME.

.SPOTTER INFORMATION STATEMENT...

WEATHER SPOTTERS ARE ENCOURAGED TO REPORT SIGNIFICANT WEATHER
CONDITIONS TO THEIR LOCAL NATIONAL WEATHER SERVICE OFFICE.

THE LATEST WEATHER INFORMATION IS AVAILABLE ON THE INTERNET AT
(LOWER CASE): HTTP://WWW.WRH.NOAA.GOV/SACRAMENTO

RANDY HARTLEY