Severe Thunderstorm Warning 22, NWS Sacramento, CA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
540 AM PDT THU APR 8 2005

.DISCUSSION...
RADAR STARTING TO LIGHT UP OVER THE NORTHERN INTERIOR COASTAL RANGE
AND NORTHERN VALLEY AS A FAST SHORTWAVE IS DROPPING DOWN THE BACK
SIDE OF THE UPPER TROUGH.  THIS SHORTWAVE IS RIDING ON A FAST MOVING
UPPER JET AND SHOULD ENTER THE FAR NORTHWEST COAST BETWEEN 6 AND
8 AM THIS MORNING.  EXPECT THIS SYSTEM TO RACE THROUGH NORTHERN
CALIFORNIA WITH LOCALLY HEAVY PRECIPITATION POSSIBLE ALONG THE
FRONTAL BOUNDARY...BUT WILL SLOW DOWN IN THE AFTERNOON.  A 120 KNOT
SPEED MAX ASSOCIATED WITH THIS SYSTEM WILL PROVIDE A QUICK SHOT OF
JET DYNAMICS BY LATE MORNING.  WITH A BRIEF PERIOD OF WIDESPREAD
HEAVY SNOW POSSIBLE LATE BY LATE THIS MORNING OR EARLY AFTERNOON
OVER THE HIGHER ELEVATIONS OF THE FAR NORTHERN INTERIOR COASTAL
RANGE AND MOUNTAINS OF WESTERN AND CENTRAL SHASTA COUNTY...HAVE KEPT
THE SNOW ADVISORY BETWEEN 8 AM AND 6 PM TODAY.  IF SHOWERS DECREASE
IN COVERAGE LATER TODAY OVER THE NORTHERN MOUNTAINS...WE MAY BE ABLE
TO CANCEL THIS ADVISORY EARLY.

LOOKING AT THE LATEST SHORT TERM MODELS EARLY THIS MORNING POINTS TO
THE AIRMASS BECOMING MORE FAVORABLE FOR THUNDERSTORMS TODAY AS THE
COLD POOL OF THIS SHORTWAVE MOVES THROUGH NORTHERN CA.  LAPSE RATES
WILL STEEPEN RAPIDLY BY LATE MORNING/EARLY AFTERNOON.  LATEST
PROFILER DATA ALSO SHOWING THE LOW LEVELS WIND HAS NOW TURNED TO THE
SOUTHEAST AS SURFACE PRESSURE FALLS TO OUR NORTHWEST WITH THE
APPROACHING SURFACE LOW AND ASSOCIATED FRONT.  CHICO PROFILER IS
ALREADY SHOWING SOME MODERATE VERTICAL SPEED SHEAR.  EXPECT THE LOW
LEVEL WINDS ABOVE THE BOUNDARY LAYER TO SHIFT MORE TO THE SOUTH AND
SOUTHWEST LATER THIS MORNING. MM5 AND WSNAM ARE SHOWING A STRONG
PUSH OF ONSHORE FLOW AS SURFACE PRESSURE FALLS IS EXPECTED TO
OCCUR OVER THE SACRAMENTO VALLEY AND MOISTURE CONVERGENCE ZONE
FORMS FROM NORTHEAST TO SOUTHWEST LATER ALONG THE BOUNDARY LATE THIS
MORNING.  BUFKIT HODOGRAPH SHOWED HELICITY THROUGH 3KM TO INCREASE
ABOVE 500 BY LATE MORNING AND AT THE LOWEST LAYER THROUGH 1KM TO
INCREASE ABOVE OVER 200.  HOWEVER BEST SUPPORTING INSTABILITY ALOFT
WILL OCCUR IN THE AFTERNOON.  BEARS WATCH.

THE SHORTWAVE WILL SLAM INTO A MORE SHEARED ENVIRONMENT WITH THE
SLOW MOVING FIRST WAVE CURRENT EXITING SOUTHERN CA AND THE SHARP
UPPER TROF BASE.  WITH THE FIRST WAVE DEEPENING OVER NIGHT...EXPECT
THE SECOND WAVE TO RAPID DECREASE IN SPEED AS IT APPROACHES THE
FIRST WAVE.  THIS WILL BRIEFLY SHEARED THE MAIN CYCLONIC ROTATION OF
THE THE SECOND WAVE.  THIS WILL RESULT IN THE SPLITTING THE
SHORTWAVE BRIEFLY INTO A MULTIPLE PIECES OF ROTATING UPPER LEVEL
VORTICES.  THIS ACTUALLY MAY HELP IN PRODUCING A LESS FAVORABLE
ENVIRONMENT TO COUNTER ACT THE LOW LEVEL SHEAR ENVIRONMENT DURING
THE AFTERNOON HOURS.  THIS WILL ALSO ADD AN ADDITIONAL COMPLICATION
TO THE FORECAST. THE AXIS OF THE UPPER TROUGH WILL EXIT TO OUR EAST
LATE TONIGHT AND WE SHOULD GET A BREAK FROM THE UNSETTLED WEATHER.

DRY WEATHER WILL LIKELY RETURN FOR SATURDAY.  MODELS ARE AGREEING OF
DEVELOPING ANOTHER SYSTEM UNDER THE GULF OF ALASKA LOW EARLY NEXT
WEEK.  THIS WILL BUCKLE THE JET SOUTHWARD TOWARDS NORTHERN CA
SOMETIME DURING THE FIRST HALF OF THE WORK WEEK.  WITH THE
PATTERN...EXPECT SHORTWAVES MOVING OUT OF THE EASTERN PACIFIC TO
HAVE A GREATER IMPACT FOR OUR AREA.  IN THE CURRENT PACKAGE...HAVE
INTRODUCED A LITTLE MORE UNSETTLED WEATHER PATTERN FOR NEXT WEEK.

&&

.STO WATCHES/WARNINGS/ADVISORIES...SNOW ADVISORY 8AM TO 6PM TODAY
            MOUNTAINS OF SOUTHWEST SHASTA COUNTY AND NORTHERN LAKE
            COUNTY...
         ...SNOW ADVISORY ABOVE 3500 FEET 8AM TO 6 PM TODAY SHASTA
            LAKE AREA AND NORTHERN SHASTA COUNTY...

&&

LAM

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SACRAMENTO CA
7 AM PDT FRI APR 8 2005

CAZ013>019-063-064-066>069-081400-
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-
7 AM PDT FRI APR 8 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...TODAY

A FEW ISOLATED THUNDERSTORMS MAY DEVELOP THROUGH THIS EVENING OVER A
LARGE PORTION OF THE INTERIOR NORTHERN CALIFORNIA.  THE STRONGEST
THUNDERSTORMS WILL LIKELY PRODUCE STRONG WINDS...HEAVY RAINS AND
HAIL. ATMOSPHERIC CONDITIONS ALSO SUPPORT THE SLIGHT CHANCE THAT ONE
OF THESE THUNDERSTORMS MAY PRODUCE A FUNNEL CLOUD OR TORNADO.

PERIODS OF HEAVY SNOW MAY PRODUCE WILL PRODUCE SOME LOCALLY
HAZARDOUS DRIVING CONDITIONS.  UP TO 7 INCHES OF SNOW MAY FALL OVER
THE NORTHERN INTERIOR COASTAL RANGE AND THE MOUNTAINS OF WESTERN
SHASTA COUNTY.

REFER TO THE ZONE FORECAST (FPUS56 KSTO - ZFPSTO) FOR MORE
INFORMATION.

.DAYS TWO THROUGH SEVEN...

NO HAZARDOUS WEATHER IS 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/STO

LAM

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE SACRAMENTO CA
149 PM PDT FRI APR 08 2005

..TIME...   ...EVENT...      ...CITY LOCATION...     ...LAT.LON...
..DATE...   ....MAG....      ..COUNTY LOCATION..ST.. ...SOURCE....
            ..REMARKS..

0140 PM     FUNNEL CLOUD     3 W HAMILTON CITY       39.74N 122.07W
04/08/2005                   GLENN              CA   LAW ENFORCEMENT

            GLENN COUNTY SHERIFF REPORTS FUNNEL CLOUD ALONG HIGHWAY
            32 3 MILES WEST OF HAMILTON CITY.

&&