Area Forecast Discussion
Issued by NWS San Diego, CA

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000
FXUS66 KSGX 231201
AFDSGX

Area Forecast Discussion
National Weather Service San Diego CA
401 AM PST Fri Feb 23 2018

.SYNOPSIS...
A low pressure system over the western states will bring scattered
mostly light showers along and west of the mountains into this
morning with gusty southwest to west winds in the mountains and
deserts. Dry and warmer for the weekend with locally gusty
northeast winds near the coastal foothills in the mornings and
gusty west winds in the mountains and deserts Saturday afternoon
and evening. Another low pressure system from the north will
bring more showers with lower snow levels and stronger and gusty
west winds in the mountains and deserts for late Monday night into
Tuesday. Forecast confidence is much lower for the middle to
latter part of next week with smaller chances for mostly light
showers for Wednesday and Thursday with increasing chances for
showers for Friday and Saturday.

&&

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

.SHORT TERM (Today through Sunday)...
A low pressure system over the western states will maintain
stronger onshore flow into this morning with gusty southwest to
west winds in the mountains near the ridge tops onto the desert
slopes...in portions of the San Bernardino County deserts...and in
the northern Coachella Valley below the San Gorgonio Pass.

Scattered mostly light showers will continue into this morning
along and west of the mountains. At 330 AM...radars showed the
greatest shower coverage was across northern portions of the
Inland Empire onto the adjacent coastal mountain slopes...and in
San Diego County along and west of the mountains. A few showers
may linger near the San Diego County mountains into this
afternoon.

Dry and warmer for the weekend. The flow will turn weakly offshore
Saturday morning with gusty northeast winds near the coastal
foothills. Onshore flow for Saturday afternoon and evening will
bring gusty southwest to west winds to the mountains deserts...
with a little stronger offshore flow Sunday morning bringing
another round of gusty northeast winds near the coastal foothills.
Cold overnight temperatures will slowly moderate and high
temperatures on Sunday will warm to near average.

&&

.LONG TERM (Monday through Thursday)...
Another cold low pressure system from the north will bring more
showers for late Monday night into Tuesday with stronger and gusty
southwest to west winds in the mountains and deserts. The forecast
spread continues to be much greater for the middle to latter part
of next week.

The ensemble means of the GFS and ECMWF show weaker low pressure
near the West Coast on Wednesday into Thursday...amplifying for
Friday and Saturday. The 00Z ECMWF is closer to the ensemble means
with the placement of the through axis...but more amplified. The
GFS maintains weaker upper troughing near the West Coast. The
current forecast leans towards the ensemble means as a place
holder until the models come into better agreement with the
details. This would have a slight chance of shower for Wednesday
and Thursday with increasing shower chances for Friday and
Saturday.

&&

.AVIATION...
231000Z...Coast/Valleys and Coastal Slopes...SCT-BKN clouds with
bases between 2000 and 4000 ft MSL (tops near 9000 ft MSL) through
18Z Friday. Isolated -SHRA or -SHSN (above 3500 ft MSL) may also
occur through 18Z. Rapid clearing from north to south between 16Z
and 21Z, leaving SKC-FEW after 21Z. Breezy northeast winds are
expected near the Cajon Pass and coastal slopes of the Santa Ana
Mountains after 03Z Saturday, resulting in areas of moderate
Up/Downdrafts and LLWS. Despite the variable weather, no significant
impacts are anticipate at the TAF sites.

Mountain Ridges/Deserts Slopes and Deserts...Gusty west winds will
continue through 20Z Friday, with areas of moderate up/downdrafts
and LLWS, especially along the desert slopes. The winds should
dissipate slowly after 20Z. Though winds may surface at times for
KPSP or KTRM, significant impacts are unlikely.

&&

.MARINE...
West northwest winds 20-25 kt with gusts to 30 kt and combined seas
of 6-9 ft will continue through Friday evening. This will create
hazardous boating conditions, and a Small Craft Advisory remains in
effect through 8 PM Friday. Conditions will improve over the
weekend, though gusty west northwest winds and combined sea may pick
up again early next week as several storm systems encroach on the
region.

&&

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

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory until 10 AM PST this morning for Apple and Lucerne
     Valleys-Riverside County Mountains-San Bernardino County
     Mountains-San Diego County Mountains-San Gorgonio Pass Near
     Banning.

PZ...Small Craft Advisory until 8 PM PST this evening for Coastal
     Waters from San Mateo Point to the Mexican Border and out
     to 30 nm-Waters from San Mateo point to the Mexican Border
     Extending 30 to 60 nm out including San Clemente Island.

&&

$$

PUBLIC...17
AVIATION/MARINE...Albright



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