Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
838 PM PDT Monday Jun 1 2015
Synopsis...seasonally cool weather will continue west of the
mountains this week. Clouds will cover much of the coastal basin
during the nights and mornings. Gusty westerly winds will occur
each afternoon and evening through the passes and onto the desert
slopes. A deep marine layer and low pressure aloft will bring a
renewed chance for some drizzle or light rain showers again later in
the week along and west of the mountains. Warmer early next week.
Discussion...for extreme southwestern California including
Orange... San Diego...western Riverside and southwestern San
Thin...high clouds were drifting over the region this evening...
otherwise only patchy marine stratus was observed at 8 PM PDT. The
00z Miramar sounding had a weak inversion based near 1400 feet. This
was about 500 feet lower than this morning. The precipitable water value had decreased
as well from around 0.61 yesterday to 0.45 inch. Surface pressure
gradients were running 8-10 mbs to the deserts...supporting isolated
wind gust reports of 40 to 50 miles per hour through and below the San Gorgonio
Pass and on the windier deserts slopes at 8 PM PDT. A Wind Advisory
remain in effect through late tonight through and below the San
Gorgonio Pass...and over the San Diego County deserts.
With only patchy marine stratus well out to sea this evening...it
may take until midnight or later for the marine stratus to thicken
up. It is still expected to develop...so chances are when it does
return...it will be rather thin and burn off quickly on Tuesday.
Looks like a couple of fine days are at hand now that the extensive
marine cloud sheet has dissipated offshore. Clouds will still
develop overnight...but should burn off each morning until the
marine layer deepens again later in the week. Winds will continue
gusty on the deserts slopes late each day and continue well into the
night...so the Wind Advisory may need to be extended.
Broad cyclonic flow aloft and onshore flow will continue near
seasonal temperatures across socal through Wednesday...along with
periods of mainly night and morning marine clouds and fog. By
Thursday...a sharper trough will begin to develop along the West Coast in
response to a digging short-wave beneath an expanding eastpac ridge.
As the ridge builds aloft over the pacnw and SW Canada...the digging
trough will cut-off and drop south. The pattern will resemble a Rex
block by the weekend with a large cut-off low covering the western
u... by a strong ridge over the pacnw coast.
Most of the model guidance keeps the cut-off low center far enough
east so that any moisture from Andres does not affect socal.
However...the outlier has been some of the GFS operational runs...
which have tracked the low far enough west to tap the moisture feed
from the remains of Andres late Friday or Sat. Even this result has not
been consistent from run to run...so unless we see more guidance
trending this way...the European model (ecmwf) guidance is deemed more reliable. The
proximity of the cut-off low will result in a deep marine layer
after Wednesday...and possible drizzle or light showers. Thunderstorms do
not seem likely at this time...but low probability of precipitation are in the forecast
Warmer and dry early next week as the low pressure system
Aviation... 020300z...coast/valleys...few low clouds along the
coast and scattered high clouds through this evening. Broken/overcast low clouds
will develop along the coast early tonight...with bases around 1200
feet mean sea level and tops to 2000 feet mean sea level. Stratus will push around 25 sm
inland overnight...and lower visible to near 2-4 sm br where it nears
higher terrain. Low clouds will clear towards the coast by late Tuesday
morning. Forecaster confidence in stratus heights is moderate and
development timing is low to moderate.
Mtns/deserts...scattered high clouds with unrestricted visible through Tuesday
evening. Westerly wind gusts to 40 knots will continue
overnight...especially through and below mountain passes...and along the
800 PM...no hazardous marine weather is expected through Thursday.
Isolated showers and thunderstorms will be possible over the coastal
waters Friday and Saturday.
800 PM...south swells around 4 feet/14 seconds from Hurricane Andres
will continue moving into coastal waters this evening. This will
continue elevated surf and strong rip currents through
Wednesday...mainly along northern Orange County beaches where sets
to 6 feet will be likely along the favored south-facing beaches.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...Wind Advisory from 2 PM today to 3 am PDT Tuesday for San Diego
County deserts-San Gorgonio Pass near Banning.