Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
917 PM PST Monday Nov 30 2015
at 9 PM PST...water vapor imagery displayed a weak upper-level
trough moving into Southern California from the northwest...and a weak upper-
level ridge trailing behind. Nearly calm winds...dry air and
mostly clear skies will create another cold night for inland
areas tonight...with areas of frost expected. A frost advisory
remains in effect through 8 am Tuesday. No major changes to the
forecast with this update. Previous forecast remains on track.
gradually warmer through Wednesday...although the nights
will continue to be quite cool with areas of frost in valleys and
deserts again tonight. Cooler Friday as a low pressure trough
swings across the region with gusty westerly winds and a slight
chance for showers. Then...warmer again next weekend as high
pressure builds and dry offshore flow returns.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Previous discussion... ridging and weak to moderate offshore flow
will help high temperatures rise 5 to 10 degrees f above normal
west of the mountains by Wednesday. Strongest easterly winds will
be along coastal mountain slopes and foothills Thursday
morning...with gusts near 40 miles per hour possible.
A stronger trough will move inland from the Pacific on Friday. It
will bring showers to northern and central California...with a slight
chance across southern portions of the state. Little if any
precipitation is expected at this time. A period of gusty onshore
flow with some marine layer clouds and moisture will accompany the
trough on Friday. Then...gusty offshore flow returns with warming
The west-northwest flow pattern aloft over the eastpac favors mostly dry
conditions across socal well into next week. The 12z GFS run
continues to show dry offshore flow and well above average
temperatures across most of California for the first half of next
week. The 12z European model (ecmwf) run stands alone with a digging shortwave
trough on Tuesday. This feature could produce a few light showers if
it does materialize...however it will have limited moisture to
work with and would need to track farther to the west for anything
significant over socal.
0100400z...mostly clear with unrestricted visible through Tuesday.
800 PM...no hazardous marine weather through Thursday. A
building northwest swell on Thursday night combined with
increasing northwest winds will generate combined seas of 6 to 10
feet over the outer waters Friday and Saturday. Small craft
advisories will likely be needed then.
800 PM...a 4-5 foot/16-17 second northwest swell will
continue through Tuesday resulting in 3-5 foot surf and strong rip
currents at exposed west-facing beaches.
A much larger west-northwest swell will arrive at the beaches
Thursday night and Friday. This swell will peak Friday night at 10
feet/15 seconds over the outer waters...then lower to 5 to 6 feet
Saturday through Monday. High surf is likely late Friday through
Saturday. Elevated surf will continue through early next week.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...frost advisory until 8 am PST Tuesday for Coachella Valley-San
Bernardino and Riverside County valleys-the inland Empire-
San Diego County deserts-San Diego County valleys.