Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 292119
AFDSGX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SAN DIEGO CA
119 PM PST THU JAN 29 2015

.SYNOPSIS...
A SLOW-MOVING DISTURBANCE WILL GENERATE RAIN AND HIGH ELEVATION
SNOW AT TIMES LATER TODAY THROUGH SATURDAY...WITH THE MOST
WIDESPREAD PRECIPITATION OCCURRING FRIDAY AFTERNOON THROUGH FRIDAY
NIGHT. WARMER AND DRY NEXT WEEK WITH HIGH PRESSURE ALOFT AND WEAK
TO LOCALLY MODERATE OFFSHORE FLOW.

&&

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

AT 1 PM PST...WATER VAPOR SATELLITE IMAGERY DISPLAYED AN UPPER-
LEVEL LOW AROUND 300 MILES SW OF SAN DIEGO. VISIBLE SATELLITE
DISPLAYED WIDESPREAD MID AND HIGH LEVEL CLOUDS STREAMING OVER THE
AREA.

THE AFOREMENTIONED UPPER-LEVEL LOW WILL CONTINUE NORTHEAST THROUGH
FRIDAY AFTERNOON...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 JUST
UNDER AN INCH WILL YIELD SCATTERED LIGHT TO MODERATE SHOWERS LATER
TODAY THROUGH SATURDAY. LOCALLY HEAVY SHOWERS WILL BE
POSSIBLE AT TIMES FRIDAY...MAINLY OVER THE MOUNTAINS. THE 29/1200
UTC ECMWF AND GFS ARE IN GOOD AGREEMENT WITH TIMING OF THE PRECIP.
HOWEVER...THE GFS CONTINUES TO FORECAST AROUND DOUBLE THE STORM
TOTAL PRECIP AMOUNTS COMPARED TO THE ECMWF/GEM/NAM. THE MORE
LIKELY RESULT WILL BE VALUES BETWEEN THE SOLUTIONS. GREATEST
COVERAGE OF PRECIP WILL BE FRIDAY AFTERNOON INTO FRIDAY EVENING AS
WE HAVE WRAP-AROUND MOISTURE AND NORTH TO NORTHEASTERLY FLOW
AROUND THE LOW. OROGRAPHICS WILL HELP INCREASE PRECIPITATION
AMOUNTS ALONG NORTHEASTERLY DESERT MOUNTAIN SLOPES. SNOW LEVELS
WILL BE AROUND 7500 FT THIS EVENING...AND LOWER TO AROUND 6500 FT
BY FRIDAY NIGHT. HIGH TEMPERATURES WILL LOWER TO NEAR TO OR
SLIGHTLY BELOW NORMAL FRI AND SAT. LOCALLY WEAK TO MODERATE
OFFSHORE WINDS WILL DEVELOP SATURDAY NIGHT THROUGH AND BELOW
MOUNTAIN PASSES AND CANYONS...MAINLY IN SAN BERNARDINO AND
RIVERSIDE COUNTIES.

...FORECAST PRECIPITATION AMOUNTS TODAY-SAT...
COAST...0.05 TO 0.10 IN...LOCAL 0.20 IN
DESERTS...0.10 TO 0.25 IN...LOCAL 0.45 IN
VALLEYS...0.10 TO 0.30 IN...LOCAL 0.50 IN
MOUNTAINS...0.30 TO 0.85 IN...LOCAL 1.00 IN

...FORECAST SNOW AMOUNTS TODAY-SAT...
6500-7000 FT...T TO 3 IN
7000-8000 FT...3 TO 5 IN
ABOVE 8000 FT...UP TO 6 IN

UPPER-LEVEL HIGH PRESSURE WILL SLOWLY BUILD OVER THE REGION SUNDAY
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 TUESDAY...WITH SLIGHTLY WARMER HIGHS DEVELOPING ON
WEDNESDAY.

&&

.AVIATION...
292100Z...COAST/VALLEYS...VFR WITH UNRESTRICTED VIS THROUGH 00Z.
WIDESPREAD CIGS AOA FL100...LOWERING AFTER 00Z WITH LAYERS TO 6000
FT AFT 08Z FRI. A MARINE STRATUS LAYER BETWEEN 1500 AND 2500 FT MSL
WILL DEVELOP 03Z THROUGH 09Z THIS EVENING AND SPREAD INLAND THROUGH
FRI MORNING. AREAS OF 3-5SM VIS WITH SCATTERED LIGHT RAIN SHOWERS
ARE POSSIBLE BY 12Z FRI...BECOMING MORE LIKELY AFT 18Z FRI.

MTNS...VFR WITH CIGS AOA FL100 AND UNRESTRICTED VIS THROUGH 00Z.
CIGS LOCALLY LOWER IN BRIEF -SHRA. CIGS WILL LOWER AND OBSCURE THE
MTS AFT 08Z THROUGH 15Z FRI WITH SCATTERED LIGHT RAIN SHOWERS
DEVELOPING AFT 09Z. FRI...MTS OCCASIONALLY OBSCURED IN SHOWERS WITH
FREEZING CONDITIONS AND SNOW LIKELY ABOVE 6800 FT.

DESERTS...VFR WITH CIGS AOA FL100 AND UNRESTRICTED VIS THROUGH 00Z
FRI...CIGS GRADUALLY LOWERING TO NEAR 5000 FT THROUGH 18Z FRI.
SCATTERED SHOWERS ARE POSSIBLE AFT 15Z FRI WITH LOCAL VIS 5-6SM IN
LIGHT RAIN SHOWERS.

&&

.MARINE...
100 PM....NO HAZARDOUS MARINE WEATHER IS EXPECTED THROUGH TUE.

&&

.SKYWARN...
SKYWARN ACTIVATION IS NOT REQUESTED. HOWEVER WEATHER SPOTTERS ARE
ENCOURAGED TO REPORT SIGNIFICANT WEATHER CONDITIONS.

&&

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

&&

$$

PUBLIC...JJT
AVIATION/MARINE...JAD






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