Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
320 am PDT Sat Mar 28 2015
Synopsis... high pressure aloft will weaken and drift east over the
weekend...allowing onshore flow to increase...and a return of the
marine layer for cooler days. A shallow moist layer has brought
areas of dense fog to the coastal strip and up to about 10 miles
inland overnight and this morning. Continued hot well inland on
Saturday...then slightly cooler on Sunday. Fair...mild...and dry
weather will continue through next week...with areas of night and
morning low clouds and fog at times under westerly flow
aloft...along with periods of gusty westerly winds possible for
the inland mountain passes and desert floors.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Weak onshore gradients have commenced since late Friday along the
socal coast. The marine inversion is very shallow allowing for
areas of dense fog and very low stratus clouds to form over the
coastal waters...along the coast and up to about 10 miles inland.
Fog is also beginning to form in southern Orange County and will
continue to fill in through daybreak across coastal Orange County.
A dense fog advisory was issued Friday evening and is in effect
until 9 am this morning.
A closed upper low was located about 900 miles west-southwest of San Diego
early this morning. This feature is predicted to slide southeast through
Sunday night to central Baja California and weaken to an open trough. General
onshore flow will continue across our region during this time with
some thin high clouds likely on Sunday with the trough.
Brief shortwave ridging on Tuesday with a brief warmup across the
region. On Wednesday another shortwave will pass overhead bringing
another onshore push with cooler temperatures through the valleys.
Gradients will pickup through Wednesday night on the heels of yet
another shortwave which may be a bit stronger. Winds could become
quite gusty especially through the west to east passes and into
the desert floors Wednesday and Wednesday night as a result.
After Wednesday and through the remainder of the work
week...benign zonal flow is likely to continue with only minor
impulses bringing periods of stronger onshore flow and high clouds
overhead. A lot of disagreements in the medium range models for
next weekend as to the depth and strength of the longwave Gulf of
Alaska trough and if it might affect portions of California. Way
too far out to predict any details at this time...but at least an
interesting weather feature to keep an eye on.
280930z...coastal areas...low clouds and fog with bases 400 feet mean sea level
and tops 700 mean sea level have moved around 5 miles inland along the
coast...mainly in San Diego County. Visible 1/4 sm has been reported at
kcrq...kmyf..and ksdm. Along the immediate coast visible has been ranging
from 1/2 sm to 3 sm. The fog will slowly spread northward and affect
the coastal areas of Orange County after 28/1030z. Low clouds and fog
will dissipate and erode to the coast by around 28/1500z. Mostly
sunny skies will persist through this evening. However...after
28/2100z...patchy stratus may develop at the immediate coast.
Valleys/mountains/deserts...mostly clear with unrestricted visible
230 am...patchy dense fog through middle morning...otherwise no
hazardous marine weather is expected through Tuesday.
230 am...a south swell with a long period will create strong rip and
longshore currents this weekend...as well as elevated surf along
south-facing beaches. For details see the beach hazards
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...beach hazards statement through Sunday afternoon for Orange
County coastal areas-San Diego County coastal areas.
Dense fog advisory until 9 am PDT this morning for Orange County
coastal areas-San Diego County coastal areas.