Severe Thunderstorm Warning 18, NWS Sacramento, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PDT SUN SEP 19 2004

.DISCUSSION...CONVECTION INTENSIFIED IN THE SRN SAC VLY DURING THE
AFTN AS VORT MAX /COLD POOL ALOFT/ MOVED INTO THE BAY AREA/SRN SAC
VLY ALONG WITH NOSE OF UPPER LEVEL JET. STRONGEST CELLS PRODUCING
HAIL AND LOCALLY HEAVY RAIN DEVELOPED AND ARE MOVING ALONG A FRONTAL
BOUNDARY WHICH EXTENDS ROUGHLY FROM NEAR SUU-SAC-BLU WITH A MESO LOW
FOCUSING INFLOW OVER SAC. THIS IS DEPICTED BY LAPS SFC WIND FIELD.
CONVECTION LIKELY TO WEAKEN AT SUNSET...BUT ISSUED WSW FOR ZONE 69
AS CONVECTIVE CELLS MOVE INTO SIERNEV THIS EVENING. PCPN FALLING
INTO DRIER AIR MASS IN LOW LEVELS OVER SIERNEV ALSO LOWERED WBZS TO
NEAR 5000 FEET...AND CONVECTIVE CELLS THIS EVENING MAY ALSO CAUSE
SOME LOCALLY LOWER SNOW LEVELS. CONVECTION LIKELY TO DECREASE AS
VORT MAX MOVES OFF INTO NV AROUND MIDNIGHT...AND SUBSIDENCE AND
DRYING OCCUR IN WAKE OF VORT MAX BY MON MORNING. VISIBLE OUTFLOW
BOUNDARY FROM CONVECTION NEAR OVE EARLIER THIS AFTN IS MOVING WWD
ACROSS THE VALLEY. CONVERGENCE MUCH WEAKER AND CELLS ARE MUCH WEAKER
ON THE TAIL END OF THE VORT MAX.

SECONDARY VORT MAX SLIDING DOWN THE BACKSIDE OF THE UPPER TROF ON
MON FORECAST TO INCREASE SUBSIDENCE AND KICK UP NLY WINDS. ABOUT A 6
MBS NLY GRADIENT FROM MFR-SAC FORECAST FOR MON AFTN...WHICH MAY
CAUSE GUSTS TO 25 MPH IN THE VALLEY. OTHERWISE THE NLY FLOW WILL
GIVE A BOOST TO  MAX TEMPS IN AREAS FAVORED BY ADIABATIC WARMING.

WEAK RIDGING FORECAST TO BUILD INTO NORCAL BEHIND THIS DEEP TROF FOR
THE REST OF THE WEEK...ALTHOUGH THE GFS INDICATES A WEAK SHORT WAVE
WILL DENT THE RIDGE THU/FRI. OTHERWISE...TEMPS SHOULD REBOUND TO
NORMAL BY TUE AND CONTINUE THROUGH THE REST OF THE WEEK.   JHM

&&

.STO...STO WATCHES/WARNINGS/ADVISORIES...URBAN AND SMALL STREAM
       FLOOD ADVISORY FOR SACRAMENTO COUNTY UNTIL 6 PM.
    ...SNOW ADVISORY UNTIL 4 AM FOR THE WEST SLOPES OF THE
       NORTHERN SIERRA NEVADA.
&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SACRAMENTO CA
700 AM PDT SUN SEP 19 2004

CAZ013>019-063-064-066>069-201400-
SHASTA LAKE AREA/NORTHERN SHASTA COUNTY-
BURNEY BASIN/EASTERN SHASTA COUNTY-NORTHERN SACRAMENTO VALLEY-
CENTRAL SACRAMENTO VALLEY-SOUTHERN SACRAMENTO VALLEY-
CARQUINEZ STRAIT AND DELTA-NORTHERN SAN JOAQUIN VALLEY-
MOUNTAINS SOUTHWESTERN SHASTA TO NORTHERN LAKE COUNTIES-
CLEAR LAKE/SOUTHERN LAKE COUNTY-MOTHERLODE-
EAST FOOTHILLS/NORTH SACRAMENTO VALLEY-
WESTERN PLUMAS COUNTY/LASSEN PARK-WEST SLOPE NORTHERN SIERRA NEVADA-
700 AM PDT SUN SEP 19 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

.DAYS TWO THROUGH SEVEN...

NO HAZARDOUS WEATHER IS EXPECTED AT THIS TIME.

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

CRS