Severe Thunderstorm Warning 5, NWS Sacramento, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
330 PM PDT WED MAY 19 2004

.DISCUSSION...UPPER LEVEL LOW PRESSURE TROUGH IS DIGGING SOUTHWEST
AROUND 130W AND APPROACHING 30N. THIS TROUGH IS THE AXIS IN WHICH
MULTIPLE SHORTWAVES ARE ROTATING THROUGH BRINGING CUMULUS CLOUDS AND
SHOWERS AND THUNDERSTORMS TO THE CWA. SATELLITE IMAGERY INDICATES
CONVECTION OCCURRING IN CONJUNCTION WITH THE SHORTWAVE ROTATING JUST
SOUTH OF THE CA/OR BORDER. THE 12Z ETA MODEL PROGGED A SHORTWAVE TO
MOVE ACROSS CENTRAL CALIFORNIA THIS AFTERNOON AS WELL. THIS WAS A
GOOD SOLUTION...SHOWERS AND THUNDERSTORMS ARE NOW POPPING UP ALONG
THE SIERRA NEVADA. WITH THE HELP OF AFTERNOON
HEATING...THUNDERSTORMS HAVE ALSO POPPED UP OVER THE PAST COUPLE OF
HOURS ACROSS THE NORTHERN ZONES. THE BEST CHANCES OF THUNDERSTORMS
TONIGHT WILL BE OVER THE HIGHER TERRAIN AND OVER THE NORTHERN AND
CENTRAL SACRAMENTO VALLEY...WHERE LOW LEVEL CONVERGENCE WILL BE A
FACTOR.

A STRONGER SHORTWAVE WHICH WILL BECOME A CLOSED LOW...WILL MOVE
THROUGH NORTHERN CALIFORNIA ON THURSDAY...BRINGING A BETTER CHANCE
FOR AFTERNOON SHOWERS AND THUNDERSTORMS. THE GFS MODEL HAS THIS VORT
MAX PROGGED TO MOVE THROUGH THE SACRAMENTO AREA BY AFTERNOON. WITH
THE MORE SOUTHERN TRACK OF THIS SYSTEM...ISOLATED THUNDERSTORMS ARE
POSSIBLE IN THE SOUTHERN SACRAMENTO VALLEY AND DELTA. SEVERAL MORE
UPPER LEVEL DISTURBANCES WILL ROTATE THROUGH THE REGION ON
FRIDAY...CONTINUING SLIGHT CHANCES OF PRECIPITATION THROUGH FRIDAY
AFTERNOON.

FOR THE EXTENDED PERIODS...THE MAIN UPPER LEVEL TROUGH WILL BEGIN TO
TRACK TO THE EAST ON SATURDAY. AN ACTIVE WEATHER PATTERN WILL
CONTINUE HOWEVER...AS THE TROUGH WILL BE QUICKLY REPLACED BY ANOTHER
LOW MOVING DOWN FROM WESTERN CANADA. THE MID RANGE MODELS ARE IN
FAIRLY GOOD AGREEMENT...BRINGING THIS NEXT SYSTEM FARTHER SOUTH INTO
CALIFORNIA BY THE MIDDLE OF NEXT WEEK. THE MODELS HAVE BEEN SHOWING
THIS FOR A COUPLE OF RUNS NOW. WITH THIS SOLUTION...SLIGHT CHANCES
FOR PRECIPITATION ARE POSSIBLE OVER MUCH OF THE CWA...EXCLUDING
NORTHERN SAN JOAQUIN VALLEY.

&&

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

&&

CRS

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SACRAMENTO CA
700 AM PDT WED MAY 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-EAST FOOTHILLS/NORTH SACRAMENTO
VALLEY-MOTHERLODE-WESTERN PLUMAS COUNTY/LASSEN PARK-WEST SLOPE
NORTHERN SIERRA NEVADA-
700 AM PDT WED MAY 19 2004

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...TODAY

ISOLATED TO WIDELY SCATTERED THUNDERSTORMS ARE POSSIBLE OVER THE
NORTHERN MOUNTAINS AND IN THE NORTHERN AND CENTRAL SACRAMENTO VALLEY
TODAY.

.DAYS TWO THROUGH SEVEN...

ISOLATED TO SCATTERED THUNDERSTORMS ARE POSSIBLE OVER MOST OF THE
NORTHERN INTERIOR PORTION OF CALIFORNIA ON THURSDAY.  THE HIGHER
TERRAIN OF INTERIOR NORTHERN CALIFORNIA MAY EXPERIENCE ADDITIONAL
ISOLATED THUNDERSTORMS ON MONDAY.

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

LAM