Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
337 am PDT Wednesday Jun 3 2015
below normal temperatures and breezy winds in the mountains and
deserts will continue through this weekend as upper-level low
pressure approaches the region. A deep marine layer will help low
clouds develop over the coast and valleys each night...and create
drizzle at times in the mornings through Friday. Isolated showers
are possible...mainly over portions of the mountains and high deserts
Friday afternoon and evening as the upper level low pressure area
passes over Southern California. Slight warming and a return to a shallower
marine layer early next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Satellite fog product is indicating the marine stratus decks have
infiltrated through the valleys and into the inland Empire early this
morning. Onshore gradients have been persistent between 7 to 8 mb
from San Diego to Daggett overnight and expected to continue
at a moderate clip the next couple of days. Wind gusts in the
favorable west to east passes have been as high as 55 miles per hour
overnight. Expect occasional gusts to continue at times through
Friday given the robust onshore flow.
Water vapor satellite is indicating the approach of the well
discussed upper level trough as it approaches the northern
California coast this morning. This feature will contribute to the
robust onshore flow through Friday with below normal
temperatures...and some marine stratus drizzle at times during the
late night and early morning each day. Meanwhile...the tropical
moisture plume from Andres has been making a Beeline north
overnight but is already showing signs of a turn to the right
which is in good agreement in the models now. This moisture plume
will be shunted to the east and will likely almost completely
bypass our region.
Meanwhile #2...Hurricane Blanca located near 105w and 12n is
forecast to reach major hurricane status later today (see National
Hurricane Center products for more details). Forecaster confidence
in where the tropical moisture plume from Blanca will end up is
low at this time and we can't rule out some precipitation early
next week based on several different scenarios. The ec solution
continues to be on the dry side for socal and that seems a little
more likely given the consistency in that solution over the last
With the first tropical moisture plume bypassing our region any
chance for precipitation rests with the passing upper level
trough. The approach and maximization of the trough should occur
Friday and given diurnal instability and limited moisture...cannot
rule out isolated showers Friday afternoon and evening. The best
chance for said showers will be closer to the low passage...in the
high deserts and the san Bern mountains. At this time the
instability parameters do not seem to support thunderstorms but
that will be something to keep an eye on during the next couple of
model runs. Have removed the mention of showers for Saturday.
As mentioned the forecast for early to middle next week has low
confidence due to the evolution of the remnants of Hurricane
Blanca. For now we are forecasting higher than climatology probability of precipitation for
Monday-Wednesday however not high enough to mention in the forecast at this
time. Beyond Blanca...a large high pressure ridge is expected to build
over California around middle next week bringing a return to shallow
marine layer and much warmer inland temperatures.
030900z...low clouds will continue their March into the inland
valleys through sunrise. Bases will be around 1800 feet mean sea level with
tops to 2500 feet. Scatter out will be 17-19z. Low clouds will move
ashore after 01z this evening with bases around 2000 feet mean sea level and
tops to 3000 feet. Above and beyond the marine layer...mostly clear
skies and VFR conditions today and tonight. Pockets of gusty winds
in lower deserts and through mountain passes late afternoon through
tonight...particularly north of kpsp.
200 am...no hazardous marine weather is expected through Sunday.
200 am...southerly swell from Tropical Storm Andres will continue
today and gradually fade Thursday. Expect big surf and strong rip
currents into Thursday...particularly in Orange County. See surf
forecast for details...laxsrfsgx.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.