FXUS66 KSTO 061825
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1025 AM PST SUN DEC 6 2009
.DISCUSSION...
RECORD TEMPERATURES THIS MORNING IN THE CENTRAL VALLEY. SOME LIGHT
SNOW IS ALREADY DEVELOPING ALONG THE SIERRA CREST THIS MORNING. THE
MODELS INCREASE THE INTENSITY THIS EVENING...SO WILL ISSUE A WINTER
STORM WARNING LATER TODAY.
COLD AIR FOR THE THE SYSTEM DROPPING DOWNFALL CONTINUE TO RETROGRADE
SOUTHWEST OVER NORTHERN CALIFORNIA TODAY AND TONIGHT. AS THE
SYSTEM BACKS OVER THE PACIFIC IT WILL PICK UP SOME MOISTURE FROM
MOVING OVER THE OCEAN AS WELL AS MOISTURE FROM THE LOW PRESSURE AREA
OUT NEAR 130W. THE COLD AIR IN PLACE WILL ALLOW FOR VERY LOW SNOW
LEVELS...SOME MODELS CONTINUE TO INDICATE SNOW OVER PORTIONS OF
THE CENTRAL VALLEY MONDAY MORNING. MUCH LIGHTER PRECIPITATION IS
EXPECTED OVER THE FAR NORTH WITH THE HIGHER PRECIPITATION TOTALS AS
YOU MOVE SOUTHWARD WITH THIS STORM. PRECIPITATION AMOUNTS STILL
REMAIN A LITTLE UNCERTAIN AT THIS TIME BUT THEY COULD RANGE FROM A
TRACE TO A FEW HUNDREDTHS OVER THE FAR NORTH END OF THE VALLEY TO UP
TO A THIRD OF AN INCH OR SO OVER THE SOUTHERN SACRAMENTO AND
NORTHERN SAN JOAQUIN VALLEY...WHILE THE WESTERN SLOPES COULD RANGE
FROM A QUARTER OF AN INCH NEAR LASSEN PARK UP TO AN INCH FOR THE
WEST SLOPES OF THE SIERRA NEVADA. DUE TO THE COLD DRY AIR RAIN TO
SNOW RATIOS WILL BY VERY HIGH. THE HIGHEST PRECIPITATION TOTALS ARE
EXPECTED SOUTH OF HIGHWAY 70.
BEHIND THE SYSTEM EVEN COLDER AIR WILL ADVECT OVER THE REGION AND
SKIES SHOULD BE CLEARING MONDAY NIGHT FOR THE VALLEY WITH WINDS NOT
EXPECTED TO BE A MAJOR FACTOR BEHIND THE SYSTEM. THAT SETS THE STAGE
FOR EVEN COLDER TEMPERATURES AT NIGHT FOR TUESDAY MORNING. THE COLD
AIR STAYS IN PLACE THROUGH AT LEAST WEDNESDAY MORNING SO WILL EXPAND
THE HARD FREEZE WATCH TO INCLUDE THAT TIME PERIOD.
&&
.AVIATION...
SOME LOW CLOUDS THIS MORNING OVER THE SOUTHERN SACRAMENTO AND
NORTHERN SAN JOAQUIN VALLEYS THIS MORNING BRINGING AREAS OF MVFR
CONDITIONS AND LOCAL LIFR/IFR CONDITIONS DUE TO FG UNTIL AROUND 19Z
THIS MORNING NEAR KMOD AND SOUTH. GUSTY SOUTHEASTERLY TO
SOUTHWESTERLY WINDS EXPECTED IN THE VALLEY AND DELTA TODAY AHEAD OF
THE NEXT SYSTEM. CLOUDS ARE EXPECTED TO INCREASE THIS EVENING FOR
MVFR CONDITIONS WITH AREAS OF IFR/LIFR CONDITIONS IN PRECIPITATION
AFT 06Z WITH ENERGY MOVING THROUGH THE AREA OVERNIGHT INTO MONDAY.
SNOW LEVELS MAY BE DOWN TO THE VALLEY FLOOR SO PUT RASN IN TAFS FOR
MONDAY MORNING FOR NOW BUT MAY BE SNOW IN THE SACRAMENTO AREA AND
NORTHERN SAN JOAQUIN VALLEY TOMORROW MORNING. THE HEAVIEST
PRECIPITATION IS EXPECTED IN THE SIERRA AND AROUND INTERSTATE 80 AND
SOUTH IN THE VALLEY MONDAY MORNING.
LOW CLOUDS AND ISOLATED SHOWERS OVER THE MOUNTAINS THIS MORNING
BRINGING MVFR CONDITIONS WITH AREAS OF IFR/LIFR CONDITIONS.
PRECIPITATION IS EXPECTED TO BECOME HEAVIER AND MORE WIDESPREAD BY
THIS EVENING FOR GENERALLY IFR CONDITIONS WILL LOCAL LIFR CONDITIONS
ACROSS THE SIERRA TONIGHT INTO MONDAY. LOCAL SOUTHWEST WINDS GUTS UP
TO 50 MPH ARE POSSIBLE OVER THE MOUNTAINS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY EVENING FOR THE
WEST SLOPES OF THE NORTHERN SIERRA NEVADA...WESTERN PLUMAS COUNTY
AND THE LASSEN PARK AREA...AND THE FOOTHILLS OF THE NORTHERN SIERRA
NEVADA AND MOTHERLODE.
WINTER STORM WATCH FROM THIS EVENING THROUGH MONDAY MORNING FOR
SOUTHERN LAKE COUNTY.
WINTER STORM WATCH FROM LATE TONIGHT THROUGH MONDAY EVENING FOR THE
SOUTHERN SACRAMENTO VALLEY...DELTA AND NORTHERN SAN JOAQUIN VALLEY.
HARD FREEZE WATCH FOR LATE MONDAY NIGHT AND TUESDAY MORNING FOR
INTERIOR NORTHERN CALIFORNIA BELOW 2000 FEET.
&&
$$
