Tornado in California, December 26, 2005

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1000 PM PST SUN DEC 25 2005

.DISCUSSION...
MAIN BAND OF PRECIPITATION ASSOCIATED WITH THE COLD FRONT HAS MOSTLY
MOVED TO THE SOUTHEAST OF THE FORECAST AREA THIS EVENING. SNOW
LEVELS HAVE BEGUN TO LOWER AND WILL BE AROUND 3500 TO 4000 FEET IN
THE NORTHERN MOUNTAINS AND 4000 TO 5000 FEET IN THE NORTHERN SIERRA
OVERNIGHT. NUMEROUS SHOWERS AND A FEW THUNDERSTORMS ARE EXPECTED THE
REMAINDER OF THE NIGHT AS THE UPPER TROF NEARS THE COAST AND TAKES
ON A SLIGHTLY NEGATIVE TILT. THE UPPER TROF AXIS WILL MOVE ACROSS
THE REGION EARLY MONDAY WITH SHOWERS MOSTLY ENDING AT THE LOWER
ELEVATIONS BY MIDDAY. SOME UPSLOPE COMPONENT AND INSTABILITY WILL
CONTINUE TO BE A PROLIFIC SNOW PRODUCER OVER THE WEST SLOPES OF THE
NORTHERN SIERRA THROUGH MONDAY AFTERNOON.

WEAK RIDGING WILL RESULT IN A VERY BRIEF RESPITE IN PRECIPITATION
BEFORE THE NEXT SET OF WAVES APPROACHES AND BEGINS TO GENERATE WARM
ADVECTION PRECIPITATION ACROSS THE NORTHERN MOUNTAINS MONDAY NIGHT
SPREADING SOUTHWARD ON TUESDAY AND WEDNESDAY. THIS SERIES WILL ONCE
AGAIN BRING A JUMP IN SNOW LEVELS TO OVER 8000 FEET BY EARLY
WEDNESDAY...AND WITH DEEP MOISTURE ADDED TO THE FAVORABLE
OROGRAPHICS AND STRONG FORCING WILL GENERATE MORE HEAVY
PRECIPITATION IN THE SHASTA AND NORTHERN SIERRA BASINS. THE COLD
FRONT IS FORECAST TO FINALLY SLIDE SOUTHWARD LATE WEDNESDAY AND
WEDNESDAY NIGHT WHICH WILL HELP TO TURN PRECIPITATION MORE SHOWERY
AND LOWER SNOW LEVELS.

THE STRONG ZONAL PATTERN ACROSS THE PACIFIC IS FORECAST TO CONTINUE
THROUGH THE REMAINDER OF THE YEAR AND INTO AT LEAST EARLY JANUARY
WITH ANOTHER STORM EXPECTED FRIDAY/SATURDAY AND YET ANOTHER FOR
MONDAY.

&&

.AVIATION...
PRECIPITATION WILL CONTINUE OVERNIGHT...SHOWERY IN NATURE ACROSS THE
VALLEY AND MORE STRATIFORM ACROSS THE FOOTHILLS AND SIERRA. ACROSS
TWEB ROUTES 413/415 WILL LOWER SNOW LEVELS A BIT MORE TOWARDS 5K FT.
CEILINGS HAVE COME UP QUITE A BIT ACROSS THE TAF VALLEY LOCATIONS
AND WILL BUMP UP CURRENT VALUES FOR THE 06Z PACKAGE. VERY UNSTABLE
AIR OFFSHORE AS SEEN BY LIGHTNING STRIKES ALONG THE COAST NEAR
EUREKA. FEEL THAT MOST OF THIS INSTABILITY WILL REMAIN ALONG THE
COAST...BUT MAY HAVE TO ADD T-STORM INTO THE 415 TWEB.

&&

.STO WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING THIS EVENING THROUGH MONDAY AFTERNOON FOR THE
WEST SLOPES OF THE NORTHERN SIERRA NEVADA...WESTERN PLUMAS COUNTY...
AND THE LASSEN PARK AREA.

WINTER WEATHER ADVISORY TONIGHT THROUGH NOON MONDAY FOR BURNEY
BASIN...MOUNTAINS OF SHASTA COUNTY...AND THE INTERIOR COAST RANGE
NORTH OF CLEAR LAKE ABOVE 4000 FEET.

&&

HAZARDOUS WEATHER OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE SACRAMENTO CA
700 AM PST SUN DEC 25 2005

CAZ013>019-063-064-066>069-261500-
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 PST SUN DEC 25 2005

THIS HAZARDOUS WEATHER OUTLOOK IS FOR INTERIOR NORTHERN CALIFORNIA.

.DAY ONE...TODAY

RAIN AND SNOW WILL INCREASE ACROSS THE REGION BY THIS AFTERNOON.
SNOW LEVELS WILL LOWER TO 5500 FEET IN SHASTA COUNTY...TO 6500 FEET
IN THE CENTRAL SIERRA. A WINTER STORM WARNING IS IN EFFECT FOR THE
SIERRA BEGINNING THIS EVENING. A SNOW ADVISORY IS IN EFFECT FOR THE
MOUNTAINS OF THE SHASTA-TRINITY FOREST BEGINNING TONIGHT.

GUSTY WINDS AND LOCALLY HEAVY RAIN SHOWERS WILL DEVELOP ACROSS THE
VALLEYS BY LATE THIS EVENING.

* WINTER WEATHER MESSAGE.......SEE WWUS46 KSTO - NPWSTO FOR DETAILS *

.DAYS TWO THROUGH SEVEN...MONDAY THROUGH SATURDAY

RAIN AND SNOW WILL CONTINUE INTO MONDAY AFTERNOON BEFORE TAPERING
OFF TO SCATTERED SHOWERS. A VERY ACTIVE WEATHER PATTERN WILL
CONTINUE OVER INTERIOR NORTHERN CALIFORNIA THROUGH THE WEEK. HEAVY
RAIN IN THE VALLEYS AND HEAVY SNOW IN THE MOUNTAINS WILL MAKE TRAVEL
HAZARDOUS AT TIMES. RIVERS AND STREAMS MAY END UP RUNNING HIGHER AND
FASTER THAN NORMAL.

* WINTER WEATHER MESSAGE.......SEE WWUS46 KSTO - WSWSTO FOR DETAILS *

* HYDROLOGIC OUTLOOK...........SEE FGUS76 KSTO - ESFSTO FOR DETAILS *

.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