000
FXUS66 KSTO 110620
AFDSTO

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1015 PM PST WED MAR 10 2010

.DISCUSSION...
WARM ADVECTION CLOUDS ARE RAPIDLY SPREADING SEWD ACROSS THE NWRN
CORNER OF NORCAL...AND ARE MOVING ACROSS OUR NRN MTN/VLY ZONES. THE
GFS N-S CROSS SECTION SHOWS 90% RH AT 700 MBS SPREADING SWD TO JUST
N OF SAC BY 12Z THU. THIS LOOKS TO BE CORRELATED TO THE WARM CLOUD
TOPS SPREADING FARTHER INLAND. THESE CLOUDS MAY HAVE AN AMELIORATING
INFLUENCE ON MIN TEMPS ACROSS THE FAR NRN ZONES TONIGHT AND PRECLUDE
FROST. ELSEWHERE...A CHILLY NIGHT IS EXPECTED WITH CLEAR SKIES AND
LIGHT WINDS PORTENDING GOOD RADIATIONAL COOLING AND THE POSSIBILITY
OF SOME LIGHT FROST IN THE INTERIOR VLY THU MORNING.

THE HIGHLY AMPLIFIED POSITIVELY TILTED RIDGE OVER THE AREA WILL BE
SHIFTING INLAND ON THU...AHEAD OF THE DEEPENING GULF OF AK TROF. THE
ORIENTATION OF THE RIDGE WILL ALLOW WAA CLOUDS TO SPREAD
PROGRESSIVELY EWD DURING THE DAY...SO AN INCREASE IN CLOUD COVER IS
EXPECTED. THIS FIRST DECK OF CLOUDS MAY WORK THROUGH THE RIDGE BY
THU MORNING...WITH ADDITIONAL CLOUD COVER SPREADING INLAND DURING
THE DAY. MILDER AIR WILL ALSO BE SPREADING INLAND AS WELL WITH
THICKNESSES AND 850 MBS TEMPS FORECAST TO WARM 8 DAM/5 DEG OR SO.
MAX TEMPS ON THU MAY BE ABOUT 5 TO 10 DEG WARMER THAN TODAY...EXCEPT
IN AREAS WHERE THE CLOUD COVER INCREASES/THICKENS. THE INCREASING
CLOUD COVER ON THU WILL BE THE FORERUNNER OF THE NEXT STORM.   JHM


.PREVIOUS DISCUSSION...
RAIN WILL BEGIN TO SPREAD INTO THE COASTAL AND NORTHERN MOUNTAINS
THURSDAY NIGHT. A RATHER SIGNIFICANT MOISTURE TAP OF AROUND 1.1 INCH
PW WILL SUPPLY THIS SYSTEM. THIS COUPLED WITH STRONG DYNAMIC LIFT
WILL BRING SIGNIFICANT SNOW OVER THE MOUNTAINS FRIDAY AND FRIDAY
NIGHT. HAVE ISSUED A WINTER STORM WATCH FOR THE MOUNTAINS STARTING
FRIDAY MORNING AND ENDING EARLY SATURDAY. A FOOT OR MORE OF SNOW IS
POSSIBLE OVER THE HIGHER MOUNTAINS. SNOW LEVELS WILL BEGIN OVER 5000
FEET THEN WILL DROP FRIDAY NIGHT. LEVELS HAVE THE POTENTIAL TO DROP
TO 2000 FEET OR LOWER OVER SHASTA COUNTY LATE FRIDAY NIGHT INTO
EARLY SATURDAY...ALTHOUGH PRECIPITATION SHOULD BE WINDING DOWN AT
THAT POINT. THE SIERRA SHOULD REMAIN ABOVE 3000 FEET THROUGH THE
EVENT.

STRONG RIDGING BY SATURDAY AFTERNOON WILL BRING CLEARING AND WARMER
WEATHER. THERE MAY BE SOME LIGHT SNOW SHOWERS PERSISTING OVER THE
SIERRA INTO THE AFTERNOON. HIGH TEMPERATURES IN DOWNTOWN SACRAMENTO
MAY REACH 70 ON SUNDAY...WHICH HAS NOT HAPPENED YET THIS YEAR. THE
NORTHERN SACRAMENTO VALLEY SHOULD REACH THE LOW 70S. EK


.EXTENDED DISCUSSION (SUNDAY THROUGH WEDNESDAY)...
RIDGE OF HIGH PRESSURE OVER THE AREA SUNDAY AND MONDAY BRINGING WARM
TEMPERATURES AND DRY WEATHER.  VALLEY LOCATIONS MAY SEE TEMPERATURES
IN THE LOWER TO MID 70S ON MONDAY (THIS WILL BE THE FIRST TIME TO
HIT 70 IN 2010). MAX TEMPERATURES WILL BE IN THE MID 50S TO MID 60S
IN THE MOUNTAINS. THE RIDGE IS EXPECTED TO MOVE EAST ON TUESDAY AS
AN UPPER LEVEL TROUGH APPROACHES THE PACIFIC NORTHWEST BRINGING
COOLER TEMPERATURES. THE MODELS HAVE THIS SYSTEM FURTHER TO THE
NORTH THAN YESTERDAYS RUNS. THE SYSTEM MAY BRUSH BY THE FAR NORTH
BRINGING A SLIGHT CHANCE OF SHOWERS TO THE COASTAL RANGE AND SHASTA
COUNTY MOUNTAINS.

&&

.AVIATION...
VFR/MVFR CONDITIONS WITH NORTHWESTERLY WINDS AS A RIDGE OF HIGH
PRESSURE BUILDS OVER THE AREA TODAY INTO EARLY THURSDAY EXCEPT LOCAL
IFR CONDITIONS ALONG THE EAST SIDE OF THE VALLEY AND IN THE ADJACENT
FOOTHILLS UNTIL 20Z.

&&

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

&&

$$

NWS STO Office Area Forecast Discussion

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