Scientific Forecaster Discussion
Zczc laxwrkafd 050253
ttaa00 klax ddhhmm
Area forecast discussion
National Weather Service San Diego California
910 PM PDT Tuesday Aug 4 2015
High pressure aloft will bring another hot day inland on
Wednesday...while the sea breeze moderates temperatures along the
coast. Low pressure off the California coast will move inland
this weekend...bringing cooler weather Thursday through Saturday...
with increasing coastal clouds during the nights and mornings.
Higher pressure returns next week for a modest warming trend and
less coastal clouds.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The heat advisory has been expanded to the deserts of San Diego
County through 8 PM Wednesday.
Skies were clear over the region this evening. The 00z Miramar
sounding had a 5 degree c inversion based just above 1100 feet. This
was almost 400 feet lower than yesterday and allowed afternoon
temperatures to climb well into the 90s late today in the valleys.
Surface pressure gradients were holding onshore to the deserts at
around 4 mbs san to dag...and 7 mbs to the lower deserts at 8 PM
PDT. Some isolated wind gusts over 30 miles per hour were measured on the
desert slopes and near the passes.
Little chance to the ongoing forecast except to add the heat
headline to the San Diego County deserts on Wednesday with forecast maximum
temperatures expected to easily hit criteria. It will be quite warm
elsewhere as well...with even the sea breeze failing to keep
coastal areas from reaching the 80s. Any nocturnal marine cloud
development will likely be fleeting.
The high pressure area responsible will expand over the SW
overnight...then be suppressed Thursday into the weekend as an area of
low pressure off the central coast swings inland. This may be
preceded by a brief shot of monsoonal moisture from the south on
Thursday...accompanied by a few clouds and higher humidity. There is an
outside chance for isolated showers to develop over the mountains/
deserts...but the main thrust of the moisture appears to remain over
Imperial County and points east. If the models trend wetter...small
probability of precipitation may need to be added to the forecast for Thursday PM.
Otherwise...it will be cooler as onshore flow increases and heights/
thickness fall across the region. Maximum daytime temperatures will
be close to average on Thursday...then fall below average...especially
inland by Friday. Continued pleasant on Sat...followed by warmer
weather early next week.
In the extended period...the operational model runs rebuild a strong
ridge over the High Plains and southern rockies next week. This
drags heights up across socal as well...but there is some
uncertainty with just how much influence the high will have on the
weather across socal as the week wears on. For now...the latest
European model (ecmwf) ensemble solution is favored...keeping a trough near the West
Coast which would keep the days from getting too hot...and hold the
monsoon at Bay.
050400z... coast/valleys...mostly clear through 06z. After 06z
patchy stratus forming along the San Diego coast with bases 900-
1200 feet mean sea level and tops 1500 feet. Clouds with non-uniform coverage
spreading 5-10sm inland through 15z. Confidence is moderate for
broken-ovc008-012 at ksan and kcrq between 09z-15z. Low confidence
for ceilings at ksna. 2-4sm br possible at kcrq between 11-15z.
Clouds and fog clearing from the coast between 15-17z Wednesday.
Mtns/deserts...few-sct clouds at or above 20000 feet mean sea level and unrestricted visible
through Wednesday evening.
900 PM...west-northwest winds gusting 20-25 knots over the outer
coastal waters tonight...decreasing Wednesday morning...then
increasing again Wednesday afternoon and evening. The Small Craft
Advisory over the outer waters has been extended to 3 am Thursday.
The winds will decrease early Thursday morning. No other hazardous
marine weather is expected Thursday through Sat.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...heat advisory until 8 PM PDT Wednesday for Coachella Valley-San
Diego County deserts-San Gorgonio Pass near Banning.
Pz...Small Craft Advisory for winds until 3 am PDT Thursday for
waters from San Mateo Point to the Mexican border extending 30 to
60 nm out including San Clemente Island.