FXUS66 KSGX 070536
AFDSGX
AREA FORECAST DISCUSSION...CORRECTION
NATIONAL WEATHER SERVICE SAN DIEGO CA
936 PM PST SUN DEC 6 2009
.SYNOPSIS...
A STRENGTHENING WINTER STORM FROM THE NORTH WILL MOVE THROUGH
SOUTHERN CALIFORNIA MONDAY AND MONDAY NIGHT. AREAS OF RAIN AND SNOW
WILL INCREASE THROUGH THE DAY WITH PEAK INTENSITIES DEVELOPING AHEAD
AND ALONG A COLD FRONT LATE IN THE AFTERNOON AND EVENING. HEAVY SNOW
AND NEAR BLIZZARD CONDITIONS ARE LIKELY IN THE SAN BERNARDINO
MOUNTAINS ABOVE 6000 FEET...AND IN THE SAN JACINTO MOUNTAINS ABOVE
7000 FEET. WINDS WILL BE VERY STRONG WITH THIS STORM...ESPECIALLY
WITH THE PASSAGE OF THE COLD FRONT LATE IN THE DAY. THE STORM WILL
EXIT TUESDAY...BUT A MOIST FLOW OFF THE PACIFIC WILL BRING A CHANCE
FOR MORE RAIN THURSDAY AND FRIDAY.
&&
.DISCUSSION...FOR SOUTHWEST CALIFORNIA INCLUDING SAN DIEGO...
ORANGE...SOUTHWEST SAN BERNARDINO AND WEST RIVERSIDE COUNTIES.
A FEW LIGHT SHOWERS HAVE BEEN DEVELOPING AND MOVING OVER THE REGION
FROM THE WEST. THE 00Z MIRAMAR SOUNDING SHOWED A DEEP 6500 FT MOIST
LAYER BUT STILL DRY ABOVE. THE WATER VAPOR LOOP AT 02Z SHOWED ENERGY
DIGGING W AROUND THE COLD UPPER LOW OVER OREGON AND GOOD SINKING
FARTHER W NEAR 140N. FARTHER SOUTH...HIGH-LEVEL MOISTURE WAS EVIDENT
PUSHING E OFF THE PACIFIC BETWEEN 30N AND 40N OVER SOCAL. WINDS WERE
ALREADY PICKING UP IN THE MOUNTAINS AND DESERTS WITH SPEEDS OF 15 TO
30 MPH AND GUSTS AROUND 35 MPH.
ALL INDICATIONS POINT TO OUR FIRST MAJOR WINTER STORM OF THE SEASON
TO ARRIVE TOMORROW BRINGING RAIN...SNOW...AND LOTS OF WIND. LATEST
SATELLITE IMAGERY AND MODEL DATA SUPPORT THE CURRENT FORECAST.
NUMEROUS WATCHES AND WARNINGS ARE IN EFFECT...INCLUDING A FLASH
FLOOD WATCH FOR POSSIBLE DEBRIS FLOWS IN AND BELOW THE BURN AREAS.
THE 00Z NAM AND GFS CONTINUE TO RATCHET UP PRECIP AMOUNTS FOR
SOUTHERN PORTIONS OF THE CWA INDICATING SOME INFLUENCE FROM THE
REMNANT PACIFIC SYSTEM THAT ENTRAINED SUBTROPICAL MOISTURE LAST
WEEK. SATELLITE RAINFALL ESTIMATES WELL OFF THE COAST SUGGEST
MODERATE RAIN IS FALLING AND WILL MOVE ONSHORE BY DAYBREAK.
AS THE PACIFIC SYSTEM MOVES THROUGH...THE IMPRESSIVE SYSTEM OVER
OREGON WILL DIG DOWN THE COAST WITH A STRONG COLD FRONT SLATED TO
PASS THROUGH THE CWA BETWEEN 22Z ANS 02Z. AS THE STORMS INTERACT...
SURFACE LOW PRESSURE WILL STRENGTHEN PRODUCING STRONG WINDS AND
CONVERGENCE OVER THE AREA. THE STRONG LOW-LEVEL WINDS WILL PRODUCE
UPSLOPE FLOW AND ENHANCE RAIN AND SNOWFALL ON THE COASTAL SLOPES.
THE 00Z RUNS OF THE NAM AND GFS INDICATE MODERATE RAIN IS POSSIBLE
MUCH OF THE DAY TOMORROW... CAPPED OFF BY HEAVIER RAIN AS A STRONG
COLD FRONT SWEEPS RAPIDLY THROUGH THE AREA BY EVENING. THIS TYPE OF
INCREASE IN RAINFALL INTENSITY AFTER MANY HOURS OF MODERATE RAIN HAS
A HISTORY OF PRODUCING DEBRIS FLOWS IN AND BELOW BURNED AREAS.
STRONG WINDS WITH GUSTS OVER 50 MPH ARE A GOOD BET WITH THIS TYPE OF
PATTERN...EVEN OVER COASTAL AREAS. EVEN A FEW GUSTS OVER 60 MPH WILL
NOT BE OUT OF THE QUESTION BEFORE ALL IS SAID AND DONE. THIS COULD
CAUSE THE MOST DAMAGE OVER COASTAL AND NEAR COASTAL VALLEY AREAS
WHERE STRONG WINDS ARE INFREQUENT. DEAD AND DYING PALM FRONDS AND
WEAKENED TREE LIMBS ARE LIKELY TO FALL VICTIM AND CREATE A HAZARD TO
PEDESTRIANS AND MOTORISTS BY MID DAY.
SNOWFALL IN THE MTNS WILL BE DEPENDENT ON THE SNOW LEVEL...WHICH
SHOULD START OUT AT 4.5K-5K FT MON MORNING...THEN RISE TO SOMEWHERE
BETWEEN 6K-7K FEET IN THE AFTERNOON BEFORE CRASHING TO 2-3K FT MON
NIGHT. WHERE THE PRECIP REMAINS MOSTLY SNOW...MAINLY SAN BERNARDINO
MTNS ABOVE 6000-6500 FEET...TWO FEET LOOKS LIKE A GOOD BET...PERHAPS
EVEN MORE. WHATEVER SNOW FALLS IN THE SAN DIEGO COUNTY MTNS WILL
QUICKLY BE COMPACTED BY THE CHANGEOVER TO RAIN...WHICH WILL HAPPEN
EARLY DUE TO MORE WARM ADVECTION THERE..SO AMOUNTS SHOULD NOT BE ALL
THAT GREAT THERE. RIVERSIDE COUNTY LOOKS TO BE SOMEWHERE IN BETWEEN.
PRECIPITATION WILL QUICKLY DIMINISH AFTER THE FRONT MOVES THROUGH IN
THE EVENING...EXCEPT AT HIGHER ELEVATIONS WHERE STRONG WEST WINDS
WILL CONTINUE UPSLOPE PRECIPITATION. MON NIGHT IS WHEN THE SAN DIEGO
COUNTY MOUNTAINS COULD SEE SEVERAL INCHES OF SNOW. SOME LIGHT
PRECIPITATION COULD LINGER IN THE SAN DIEGO MOUNTAINS THROUGH TUE
MORNING BEFORE COMPLETELY DRYING OUT. OTHERWISE PARTLY CLOUDY AND
CONTINUED BREEZY AND COOL.
ANOTHER WARMER SYSTEM FROM THE CENTRAL PACIFIC IS EXPECTED BY THU
INTO FRI WITH LIGHT TO MODERATE RAIN POSSIBLE.
&&
.AVIATION...
070330Z...DEEP MOISTURE TO OVER 7000 FEET WILL CONTINUE TONIGHT.
LAYERS OF BROKEN TO OVERCAST STRATOCU WITH BASES RANGING BETWEEN
3500 AND 6000 FEET WILL LOWER OVERNIGHT WITH BASES BETWEEN 1500 AND
3000 FEET EXPECTED BY MONDAY MORNING IN SHOWERS. LOCALLY LOWER BASES
AND LOCAL VISIBILITIES 3 TO 5 MILES CAN BE EXPECTED ON MONDAY IN
HEAVIER RAIN...MAINLY DURING THE LATE MORNING AND AFTERNOON.
MOUNTAINS WILL BE MOSTLY OBSCURED IN CLOUDS AND PRECIPITATION
THROUGH MONDAY. STRONG SOUTH TO SOUTHWEST WINDS ARE FORECAST MONDAY
MORNING INTO THE EVENING...AS HIGH AS 40 TO 50 KNOTS AT KSAN. EXPECT
COLD FRONT PASSAGE BETWEEN 23Z AND 02Z WHEN WINDS WILL SHIFT TO
WESTERLY.
&&
.MARINE...
A STRONG COLD FRONT WILL MOVE INTO THE AREA MONDAY. IT WILL BE VERY
WINDY MONDAY AND SEAS WILL BE HAZARDOUS. THERE WILL BE A GALE
WARNING FOR THE INNER AND OUTER WATERS FROM MONDAY MORNING THROUGH
TUESDAY MORNING. A RAPID RISE IN WESTERLY SWELL WILL ACCOMPANY THE
FRONT MONDAY AFTERNOON AND EVENING...THEN DECREASE EARLY TUESDAY.
A HIGH RIP CURRENT RISK WILL DEVELOP MONDAY AFTERNOON AS SWELL AND
SURF RISE RAPIDLY.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
WINTER STORM WARNING...SEE LAXWSWSGX.
HIGH WIND WATCH...SEE LAXNPWSGX.
GALE WATCH...SEE LAXMWWSGX.
FLASH FLOOD WATCH...SEE LAXFFASGX.
&&
$$
PUBLIC...JAD
AVIATION/MARINE...MM
