Area forecast discussion
National Weather Service San Diego California
345 am PDT Thursday may 23 2013
Synopsis...
a trough of low pressure near the West Coast will maintain stronger
onshore flow through Memorial Day. This will keep high temperatures
slightly below seasonal averages with areas of night and morning
coastal low clouds and fog extending into the inland valleys. There
will also be gusty west winds in the mountains and deserts. A
stronger trough of low pressure could bring a chance of
precipitation for the early to middle part of next week.
&&
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
counties...
Short term (today through saturday)...
a trough of low pressure along the West Coast centered over the
Pacific northwest will maintain onshore flow with minor day to day
differences in the weather. High temperatures will be slightly below
seasonal averages. The onshore flow will bring locally gusty west
winds to the mountains and deserts each late afternoon through late
evening with gusts in the windier areas near advisory strength...
mainly in the northern Coachella and near the ridge tops of the San
Diego County mountains.
Satellite imagery and surface reports show lots of breaks in the
coastal stratus and a decrease in the depth of the cloud layer with
the greatest amounts of breaks over the coastal waters. Drizzle has
been removed from the forecast for this morning. The marine layer
will remain deep enough for night and morning stratus to extend into
the inland valleys with patchier coverage over the coastal waters.
&&
Long term (sunday through wednesday)...
for Sunday into Monday...a shortwave moving inland through
California should maintain the onshore flow with slightly below
seasonal temperatures...and with the marine layer extending into the
inland valleys. Gusty west winds in the mountains and deserts could
be slightly stronger.
For late Monday through Wednesday...the global models are trying to
converge on a solution with enough amplitude on a trough of low
pressure moving inland through Southern California to bring
precipitation. The GFS is slightly faster and European model (ecmwf) slightly slower
with the timing. The 00z European model (ecmwf) ensemble mean is very close the 06z
GFS with the timing. The current forecast keeps probability of precipitation just below
thresholds for precipitating weather for late Monday through
Wednesday. However...if current model trends continue...probability of precipitation will
need to be increased some for early next week.
&&
Aviation...
230930z...broken low clouds will continue over the entire coastal
basin and up the coastal mountain slopes this morning. Bases will be
2500-3000 feet above sea level with tops up to 4500 feet. Clouds will clear by
17-18z. Low clouds will redevelop and move ashore over ksan and kcrq
this evening between 01-04z...around 06-10z at ksna or not at
all...and very late briefly or probably not at all at kont. Clouds
based around 2500 feet above sea level will have random and less extensive
coverage tonight.
Above and beyond the marine layer...mostly clear with unrestricted
visible through tonight.
&&
Marine...
a short period northwest swell and in increase in northwest winds
will create choppy seas around San Clemente Island late today into
early Friday. Isolated conditions may be hazardous to small craft.
Higher and lower than normal tides...with swings of 8.9 feet...will
combine with surf to create potential minor coastal flooding Friday
through Memorial Day. Strong rip currents are expected through the
Holiday weekend.
&&
Sgx watches/warnings/advisories...
California...Wind Advisory from 3 PM this afternoon to 3 am PDT Friday for
the Coachella Valley...Riverside County mountains...San
Diego County deserts...San Diego County mountains.
Pz...none.
&&
$$
Public...17
aviation/marine...mm
