Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 282010
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
1210 PM PST WED JAN 28 2015

.SYNOPSIS...
HIGH CLOUDS AND SLIGHTLY WARMER WEATHER TODAY. A DISTURBANCE
APPROACHING THE REGION WILL CREATE THE POSSIBILITY OF RAIN AND HIGH
ELEVATION SNOW AT TIMES THURSDAY THROUGH SATURDAY. WARMER AND DRY
NEXT WEEK WITH HIGH PRESSURE ALOFT.

&&

.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...

AT 12 PM PST...WATER VAPOR SATELLITE IMAGERY DISPLAYED AN UPPER-LEVEL
TROUGH OFF THE WEST COAST STRETCHING FROM THE PACIFIC NORTHWEST TO
AROUND 700 MILES SW OF SAN DIEGO...AND A WEAK UPPER-LEVEL RIDGE
OVER SW CA. VISIBLE SATELLITE DISPLAYED MID AND HIGH LEVEL CLOUDS
STREAMING OVER THE AREA.

THE AFOREMENTIONED UPPER-LEVEL TROUGH WILL TRAVERSE EASTWARD
THROUGH THURSDAY...THEN DEVELOP A CUTOFF LOW BY FRIDAY AT THE
BASE OF THE TROUGH. THE LOW WILL SLOWLY MOVE NORTHEAST...STALL OVER
THE REGION LATE FRIDAY THROUGH EARLY SATURDAY AND TRACK SOUTH OUT
OF THE AREA BY SATURDAY NIGHT. WEAK UPPER- LEVEL INSTABILITY AND
FORECAST PRECIPITABLE WATER VALUES UNDER AN INCH WILL YIELD
SCATTERED LIGHT TO MODERATE SHOWERS THURSDAY THROUGH SATURDAY. THE
28/1200 UTC ECMWF AND GFS DIFFER IN TIMING AND AMOUNTS OF PRECIP.
HOWEVER...THE CONSENSUS SHOWS THE GREATEST PRECIP AMOUNTS
OCCURRING IN THE SAN BERNARDINO COUNTY MOUNTAINS...MAINLY ON THE
DESERT MOUNTAIN SLOPES...GIVEN THE NORTHEASTERLY FLOW AND WRAP
AROUND MOISTURE FROM THE LOW. GREATEST COVERAGE OF PRECIP WILL
LIKELY BE FRIDAY AFTERNOON INTO FRIDAY EVENING. SNOW LEVELS WILL
BE JUST BELOW 8000 FT THURSDAY...AND LOWER TO NEAR 6500 FT FRIDAY
AFTERNOON. HIGH TEMPERATURES WILL LOWER TO NEAR NORMAL FRI AND SAT.

...FORECAST PRECIPITATION AMOUNTS THU-SAT...
COAST/DESERTS...TRACE TO 0.10 IN
VALLEYS...0.05 TO 0.40 IN
MOUNTAINS...0.30 TO 0.90 IN

...FORECAST SNOW AMOUNTS THU-SAT...
6500-7000 FT...T TO 2 IN
7000-8000 FT...2 TO 4 IN
ABOVE 8000 FT...4 TO 6 IN

UPPER-LEVEL HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION THROUGH
MID NEXT WEEK. THIS...COMBINED WITH WEAK OFFSHORE FLOW...WILL RAISE
HIGH TEMPERATURES TO 5 TO 10 DEGREES F ABOVE NORMAL SUNDAY AND
MONDAY. WEAKENING OFFSHORE FLOW AND A RETURN OF THE SEA BREEZE ALONG
THE COAST WILL LOWER COASTAL HIGHS TO NEAR NORMAL TUE AND WED.

&&

.AVIATION...
282010Z...SCT HIGH CLOUDS AOA 20000 FEET MSL WILL GRADUALLY THICKEN
AND LOWER TO ABOUT 15000 FEET THIS AFTERNOON INTO TONIGHT.

&&

.MARINE...
200 PM....NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH SUNDAY
EVENING.

&&

.SKYWARN...
SKYWARN ACTIVATION WILL NOT BE NEEDED TODAY.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...JJT
AVIATION/MARINE...SMALL







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