Severe Thunderstorm Warning 4, NWS Sacramento, CA

000 
WWUS56 KSTO 102330
SVSSTO

SEVERE WEATHER STATEMENT
NATIONAL WEATHER SERVICE SACRAMENTO CA
425 PM PDT TUE JUL 10 2007

CAC089-102345-
/O.CON.KSTO.SV.W.0004.000000T0000Z-070710T2345Z/
SHASTA CA-
425 PM PDT TUE JUL 10 2007

...A SEVERE THUNDERSTORM WARNING REMAINS IN EFFECT UNTIL 445 PM PDT
FOR EAST CENTRAL SHASTA COUNTY...

AT 422 PM PDT...NATIONAL WEATHER SERVICE DOPPLER RADAR CONTINUED TO
INDICATE A SEVERE THUNDERSTORM CAPABLE OF PRODUCING DAMAGING WINDS IN
EXCESS OF 60 MPH AND PENNY SIZE HAIL.  THIS STORM WAS LOCATED OVER EAST 
CENTRAL SHASTA COUNTY...OR ABOUT 3 MILES EAST OF HAT CREEK...MOVING 
NORTH AT 20 MPH.

THE SEVERE THUNDERSTORM WILL BE NEAR...
  RURAL NORTHEASTERN SHASTA COUNTY BETWEEN CASSEL AND FALL RIVER     
  MILLS AT 440 PM PDT

LAT...LON 4071 12149 4069 12136 4099 12135 4097 12154

$$

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
300 PM PDT TUE JUL 10 2007

.DISCUSSION...
.THUNDERSTORMS HAVE ALREADY STARTED FIRING UP ACROSS THE SIERRA THIS
AFTERNOON. MOST OF THE ACTIVITY IS OVER THE HIGHER ELEVATIONS OF THE
WEST SLOPES OF THE NORTHERN SIERRA NEVADA AT THIS TIME...WITH A LINE
FROM NEAR LAKE TAHOE SOUTH TO THE YOSEMITE PARK AREA AND ANOTHER ONE
NORTH OF THERE FROM PLUMAS COUNTY SOUTH TO CENTRAL SIERRA COUNTY. AT
THIS TIME NONE OF THEM ARE SEVERE SO THEY ARE BEING HANDLED BY SHORT-
TERM FORECASTS. EXPECT THAT THE STORMS WILL SPREAD ACROSS THE REGION
AS THE UPPER LOW OFF THE COAST CONTINUES TO PUMP ADDITIONAL MOISTURE
NORTH THROUGH THE REGION. THE FIRE WEATHER WATCH WAS REPLACED BY RED
FLAG WARNINGS FOR THE WEST SLOPES AND FOOTHILLS OF FAR NORTHERN PART
OF THE SIERRA NORTHWARD TO THE NORTHEAST PLATEAU AND BURNEY BASIN ON
THROUGH 10 PM PDT TONIGHT. THESE THUNDERSTORMS COULD PERSIST ON INTO
THE NIGHT FOR MOST OF OUR AREA. ON WEDNESDAY THE UPPER LOW STARTS TO
RETROGRADE OFF THE COAST AND MOVE NORTH SO THE CHANCES OF ADDITIONAL
SHOWERS AND THUNDERSTORMS WILL BE CONFINED TO THE HIGHER ELEVATIONS.
OVERNIGHT LOWS TONIGHT WILL PROBABLY BE UP A BIT FROM THIS MORNINGS
FROM THE CLOUD COVER. BY THURSDAY THE LOW MOVES FURTHER AWAY AND IS
CAUGHT UP BY THE TROUGH ALONG THE EASTERN PACIFIC. THIS SHOULD KEEP
CHANCES OF THUNDERSTORMS MAINLY ALONG THE CRESTS OF THE SIERRA WITH
THE RIDGE OVER THE GREAT BASIN REBUILDING ENOUGH FOR FRIDAY TO KEEP
ANY CHANCE OF ADDITIONAL THUNDERSTORM OUT OF OUR AREA. THE RIDGE IS
ALSO GOING TO WARM THE TEMPERATURES BACK UP AND KEEP THEM ABOVE THE
SEASONAL NORMS FOR THE REMAINDER OF THE EXTENDED OUTLOOK PERIOD. RH

.PREVIOUS DISCUSSION...
CALIFORNIA REMAINS CAUGHT BETWEEN AN UPPER LOW OFF THE COAST AND A
RIDGE OF HIGH PRESSURE OVER THE FOUR-CORNERS AREA. THIS IS ALREADY
ENTRAINING SUB-TROPICAL MOISTURE INTO SOUTHERN CALIFORNIA FROM THE
SOUTH WITH THE LEADING EDGE OF THE CLOUD MASS ALREADY MOVING IN TO
NORTHERN SAN JOAQUIN VALLEY THIS MORNING.  THIS MOISTURE IS COMING
INTO A DRY AIR MASS WHICH WILL BE UNSTABLE AS IT CONTINUES TO MOVE
THROUGH NORTHERN CALIFORNIA TODAY. CONDITIONS SEEM RIPE TO DEVELOP
DEEP AND MOIST CONVECTIVE ACTIVITY FOR OUR ZONES BY THIS AFTERNOON.
INITIALLY ANY THUNDERSTORMS WILL LIKELY PRODUCE DRY LIGHTNING THAT
WILL INCREASE WILDFIRE RISK OVER DRY FUELS. AVAILABLE PRECIPITABLE
MOISTURE WILL INCREASE LATER IN THE DAY...WHICH COULD PROVIDE RAIN
SHOWERS WITH THE THUNDERSTORMS...DECREASING THE FIRE THREAT.  THIS
ACTIVITY WILL MOVE NORTH DURING THE NIGHT WHICH COULD KEEP THREATS
OF DIURNAL THUNDERSTORMS OVERNIGHT.  THE UPPER LOW WILL MOVE NORTH
AND WEST BY WEDNESDAY AND CHANCES OF CONVECTIVE ACTIVITY SHOULD BE
MAINLY OVER HIGHER ELEVATIONS WEDNESDAY AFTERNOON AND EVENING. FOR
THURSDAY THE UPPER LOW CONTINUES TO MIGRATE NORTH WHICH WILL CAUSE
IT TO BE ABSORBED INTO THE LONG-WAVE TROUGH IN THE EASTERN PACIFIC
THAT WILL REDUCE THE CHANCES OF THUNDERSTORMS TO MAINLY ACROSS THE
SIERRA NEVADA CRESTS. BY FRIDAY THE RIDGE TO OUR EAST WILL REBUILD
STRONG ENOUGH TO KEEP ANY CHANCES FOR SHOWERS OR THUNDERSTORMS OUT
OF OUR AREA THROUGH THE BEGINNING OF NEXT WEEK. RANDELL C. HARTLEY

&&

.AVIATION...
INCREASING MID AND UPPER LEVEL MOISTURE THIS EVENING IS BRINGING
SCATTERED THUNDERSTORMS TO THE MOUNTAINS WITH ISOLATED THUNDERSTORMS
POSSIBLE IN THE CENTRAL VALLEY AND FOOTHILLS. LOOK FOR LOCAL IFR
CEILINGS...REDUCED VISIBILITY...HAIL...AND STRONG GUSTY WINDS
WITH THE THUNDERSTORMS. VFR CONDITIONS WITH MID AND HIGH CLOUDS
EXPECTED OUTSIDE OF THUNDERSTORMS.  MARINE LAYER IS NEAR 2000 FEET
AND AREAS OF MARGINAL VFR CEILINGS WILL RETURN TO THE BAY AREA AND
INLAND COASTAL VALLEY BETWEEN 06 AND 09Z TONIGHT.

&&

.STO WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING...UNTIL 10 PM PDT
   FOR BURNEY BASIN AND NORTHEAST PLATEAU IN SHASTA COUNTY INCLUDING
   NORTHWEST LASSEN NATIONAL FOREST NORTH OF LASSEN NATIONAL PARK...
   NORTHERN SIERRA INCLUDING LASSEN NATIONAL PARK AND PLUMAS AND LASSEN
   NATIONAL FORESTS WEST OF THE SIERRA CREST...AND THE FOOTHILLS OF THE
   NORTHERN SIERRA NEVADA 1000 TO 3000 FEET MSL INCLUDING PORTIONS OF
   SHASTA...TRINITY AND BUTTE UNITS.

&&

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE SACRAMENTO CA
1100 AM PDT TUE JUL 10 2007

CAZ013>019-063-064-066>069-111400-
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-
1100 AM PDT TUE JUL 10 2007

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...TODAY

UPPER LOW PRESSURE OFF THE CALIFORNIA COAST WILL DRAW SUBTROPICAL
MOISTURE INTO NORTHERN CALIFORNIA TODAY INTO TONIGHT BRINGING A
THREAT OF THUNDERSTORMS. VERY DRY FUELS ARE ALREADY IN PLACE SO
THE POTENTIAL EXISTS FOR FIRES FROM LIGHTNING MAINLY FOR THE FAR
NORTHERN WEST SLOPES OF THE SIERRA NEVADA MOUNTAINS AND FOOTHILLS
NORTH TO THE BURNEY BASIN...THEREFORE A RED FLAG WARNING HAS BEEN
ISSUED FOR THESE AREAS.

* RED FLAG WARNING.........SEE WWUS86 KSTO - RFWSTO FOR DETAILS *

.DAYS TWO THROUGH SEVEN... WEDNESDAY THROUGH MONDAY

THUNDERSTORMS ARE POSSIBLE OVER THE COASTAL AND NORTHERN INTERIOR
MOUNTAINS...SIERRA NEVADA AND FOOTHILLS WEDNESDAY WITH A SLIGHT
CHANCE OVER THE SIERRA NEVADA THURSDAY OTHERWISE NO HAZARDOUS
WEATHER IS EXPECTED THROUGH NEXT MONDAY.

.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