Area Forecast Discussion
Issued by NWS San Diego, CA

Current Version | Previous Version | Graphics & Text | Print | Product List | Glossary Off
Versions: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28

000
FXUS66 KSGX 151020
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
320 AM PDT Sun Oct 15 2017

.SYNOPSIS...
High pressure aloft and weak offshore flow will continue well
above average high temperatures west of the mountains through
Monday with high temperatures in the valleys and inland coastal
areas in the 90s to around 100. Cooling will begin to spread
inland with onshore flow on Tuesday and Wednesday with greater
cooling on Thursday and Friday as a trough of low pressure moves
inland along the West Coast. This will bring more cloud
cover...gusty west winds in the mountains and deserts...and a
slight chance of showers for Thursday night and Friday. Dry with a
warming trend for next weekend with strengthening high pressure
aloft and moderate offshore flow.

&&

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

Early this morning...satellite imagery shows patchy stratus mostly
over the coastal waters...extending locally inland along portions
of the northern Orange County coast. Aircraft soundings late
Saturday evening showed the base of the marine inversion around
700 feet. Los Alamitos has briefly had visibility less than one
mile with low clouds and fog. Much of the stratus will remain off
the coast...but will briefly impinge on the coast at times in a
few locations. Satellite imagery also shows a few subtropical high
clouds spreading eastward across northern Baja and far southern
California.

Weak offshore flow continues with gusty northeast to
east winds near coastal foothills and below passes and canyons
with strongest gusts to around 40 mph. These winds will continue
into the morning...then diminish through the afternoon. Weaker and
more localized northeast winds will return for late tonight into
early Monday morning.

High pressure aloft combined with the offshore flow will bring
well above average high temperatures west of the mountains
through Monday with high temperatures in the valleys and inland
coastal areas in the 90s to around 100. Cooling will begin to
spread inland on Tuesday and Wednesday as weak onshore flow
returns. Mid level subtropical moisture could bring some clouds to
the mountains Tuesday and Wednesday afternoons in addition to some
high clouds.

A trough of low pressure moving inland along the West Coast on
Thursday and Friday will bring stronger onshore flow with stronger
and gusty west winds for the mountains and deserts. As the trough
of low pressure moves inland to the north...it may draw some
subtropical moisture northward into Southern California with more
clouds and a slight chance of showers for Thursday night and
Friday.

For next weekend...the GFS and ECMWF are in better agreement in
showing subtropical high pressure extending into Southern
California with the high pressure across Southern California
stronger than the high pressure this weekend. Surface high
pressure over the Great Basin could bring moderate strength
offshore flow for Sunday and Monday.

&&

.AVIATION...
151015Z...Areas of east to northeast winds 15-25 KT, with local
peak gusts 30-40 KT through/below passes and canyons through about
18Z today, decreasing and becoming more localized through wind-prone
areas for the remainder of the afternoon. The winds will produce MDT-
STG UDDFS and LLWS over and west of the mtns, including near KONT,
KSBD, and KSNA through 18Z.

Near, and along the coastal strip...areas of fog are developing
and may impact the coastal TAF sites through about 15Z this morning
with periods of VIS below 1 SM possible. Confidence is too low to
include in the TAFS in a prevailing group at this time. KSNA looks
most likely to be impacted. Otherwise, skies will be clear with
unrestricted VIS through this evening.

&&

.MARINE...
No hazardous marine weather is expected through Thursday.

&&

.BEACHES...A long period south swell will be moving through the
coastal waters Monday evening through Wednesday. The 3 to 4 FT swell
will create elevated surf, and strong rip and longshore currents.

&&

.FIRE WEATHER...
High pressure aloft combined with weak offshore flow will continue
well above average high temperatures through Monday west of the
mountains with high temperatures into the 90s to around 100 for
valley and inland coastal areas. Lowest inland humidities will
fall to around 5 percent today and Monday with poor overnight
recovery near the coastal foothills. Gusty northeast to east winds
will continue near the coastal foothills and below passes and
canyons into this morning with strongest gusts to around 40 mph.
Winds will diminish this afternoon with another round of weaker
and more localized northeast winds near the coastal foothills late
tonight into early Monday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Red Flag Warning until noon PDT today for Orange County Inland
     Areas-San Bernardino County Mountains-Including The
     Mountain Top And Front Country Ranger Districts Of The San
     Bernardino National Forest-San Bernardino and Riverside
     County Valleys  -The Inland Empire-Santa Ana Mountains-
     Including The Trabuco Ranger District of the Cleveland
     National Forest.

PZ...NONE.
&&

$$

PUBLIC/FIRE WEATHER...17
AVIATION/MARINE/BEACHES...JAD



USA.gov is the U.S. government's official web portal to all federal, state and local government web resources and services.