FXUS66 KSTO 072020
AFDSTO
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SACRAMENTO CA
1220 PM PST MON DEC 7 2009
CANCELLED WINTER WEATHER ADVISORY FOR THE NORTHERN SAN JOAQUIN
VALLEY.
.UPDATED DISCUSSION...
BACK EDGE OF PRECIP HAS NOW CLEARED STOCKTON AND JUST ON THE NW EDGE
OF MODESTO AND EXTENDING NE TOWARD JACKSON AND BLUE CANYON.
STOCKTON HAD REPORTS OF LIGHT TO MODERATE SNOW THIS MORNING...BUT
NOTHING APPEARED TO STICK ON THE GROUND. MODESTO HAS STAYED
STRICTLY RAIN. FOLSOM HAD REPORT OF 1-2 INCHES AT 600 FT WHILE
LINCOLN HAD 2-3 INCHES ON CARS ON 500 FT. THE ONCE GOOD OROGRAPHIC
FLOW COMPONENT OVER THE SIERRA IS GRADUALLY DIMINISHING. SNOW WILL
SUBSIDE OVE THE MTNS AS THE DAY PROGRESSES...SO WILL UPDATE FORECAST
LATER THIS MORNING TO TAKE OUT MENTION OF PRECIP EXCEPT FOR SIERRA.
THUS ENDING THE WINTER STORM WARNING AND WINTER WEATHER ADVISORY FOR
THE CENTRAL VALLEY. HARD FREEZE IS STILL IN EFFECT FOR TONIGHT AND
TUE MORN. HAVE A GREAT DAY AND REMEMBER PEARL HARBOR. JMC
.PREVIOUS DISCUSSION...
COLD CLOSED UPPER LOW ORIGINATING FROM WESTERN CANADA HAS ITS CENTRE
NOW OVER FAR NORTHERN CALIFORNIA. THE SYSTEM IS FORECAST TO OPEN UP
AND MOVE EAST LATER TODAY. THIS WILL SET THE STATE FOR BETTER
POTENTIAL FOR BREAKTHROUGH UNDER THE STRONG BLOCKING HIGH OVER THE
NORTHERN GULF OF ALASKA LATER THIS WEEK. NEXT SYSTEM EXPECTED TO
WEAKEN AS IT MOVES INTO THE REGION THURSDAY.
LIGHT TO MODERATE PRECIPITATION CONTINUES ALONG AND AHEAD OF THE
COLD FRONT WHICH LIES ALONG THE I-80/US-50 CORRIDOR. IN THE
VALLEY...MOST OF THE PRECIPITATION IS OCCURRING FROM AROUND TURLOCK
NORTHWARD TO JUST SOUTH OF MARYSVILLE. THIS WHOLE BAND IS ONLY
MOVING SLOWLY OFF TO THE SOUTHEAST AS IT PIVOTS AHEAD OF THE UPPER
TROUGH DIGGING OFF THE NORTH COAST. UPPER DIFFLUENCE AHEAD OF THE
TROUGH CONTINUES TO FAVOR UPWARD VERTICAL MOTION AHEAD OF IT WITH
THE HEAVIEST PRECIPITATION FOCUSED OVER SACRAMENTO COUNTY EASTWARD
INTO THE FOOTHILLS AND WEST SLOPES OF THE NORTHERN SIERRA NEVADA.
RAIN MIXED WITH SNOW IS BEING OBSERVED ON THE VALLEY FLOOR IN THE
SACRAMENTO AREA EARLY THIS MORNING (TEMPERATURES GENERALLY IN THE
MID 30S) WITH REPORTS OF SNOW STICKING TO GRASSY SURFACES ABOVE
ABOUT 500 FEET OF ELEVATION. AREAS AROUND 1000 FEET WILL LIKELY SEE
SOME ACCUMULATING SNOW THE NEXT SEVERAL HOURS AS HEAVIER
PRECIPITATION MOVES IN AND THE AIRMASS CONTINUES TO COOL.
PRECIPITATION EXPECTED TO END IN THE SACRAMENTO VALLEY BY THIS
AFTERNOON AND TAPER OFF IN THE NORTHERN SIERRA NORTH OF I-80...AND
TAPER OFF ACROSS THE REMAINDER OF THE MOTHERLODE AND NORTHERN SIERRA
BY LATE THIS AFTERNOON AND EARLY THIS EVENING. PORTIONS OF THE
MOTHERLODE AND WEST SLOPES OF THE NORTHERN SIERRA WILL SEE
IMPRESSIVE SNOWFALL TODAY.
CLEARING SKIES TONIGHT OVER THE VALLEY WILL ALLOW GOOD RADIATIONAL
COOLING AND WITH COLD AIRMASS IN PLACE...VERY COLD TEMPERATURES
EXPECTED (20S WITH SOME LOCAL SPOTS POSSIBLY DIPPING INTO THE UPPER
TEENS).
COLD DRY PATTERN CONTINUES THROUGH WEDNESDAY.
&&
.EXTENDED DISCUSSION (FRIDAY THROUGH MONDAY)...ECMWF AND GEM SHOW
SOME SHORTWAVE ENERGY SPREADS INTO THE AREA FRIDAY. MOIST WESTERLY
FLOW ALONG WITH 110 KT JET WILL BRING THE POTENTIAL FOR VALLEY RAIN
AND MOUNTAIN SNOW. LATEST OPERATION RUNS OF GFS SHOWING WEAKER
SYSTEM. A MORE SIGNIFICANT SYSTEM IS POSSIBLE SATURDAY INTO SUNDAY.
&&
.AVIATION...
COLD STORM SYSTEM IS SLOWLY MOVING SOUTH OUT OF THE AREA WITH THE
MAIN BAND OF PRECIPITATION SOUTH OF KSCK. RAIN SHOWERS ARE POSSIBLE
IN THE VALLEY WITH LOCAL IFR CONDITIONS THROUGH THE VALLEY. CLEARING
SKIES TONIGHT WITH RECENT MOISTURE WILL ALLOW AREAS OF FOG TO FORM
BRINGING AREAS OF MVFR AND LOCAL IFR/LIFR CONDITIONS AFT 06Z UNTIL
AROUND 18Z TUESDAY.
PRECIPITATION AND LOCALLY GUSTY SOUTHWEST WINDS UP TO 50 MPH WILL
CONTINUE IN THE SIERRA THROUGH THE AFTERNOON WITH LIFR/IFR
CONDITIONS. SKIES SHOULD CLEAR FOR VFR/MVFR CONDITIONS OVERNIGHT
EXCEPT VALLEY FOG FORMING FOR LOCAL IFR/LIFR CONDITIONS.
&&
.STO WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING UNTIL 6 PM PST THIS EVENING FOR MOTHERLODE AND
WEST SLOPES NORTHERN SIERRA NEVADA.
FREEZE WARNING FROM 2 AM TO 9 AM PST TUESDAY FOR SACRAMENTO
VALLEY...DELTA AND NORTHERN SAN JOAQUIN VALLEY AND SURROUNDING
FOOTHILLS INCLUDING SOUTHERN LAKE COUNTY.
&&
$$
