Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service San Diego California
814 PM PDT Monday Aug 3 2015
Synopsis... high pressure strengthening over the southwest will
bring hot days inland through midweek...while a shallow marine layer
keeps coastal areas more moderate with periods of night and morning
low clouds and fog. A trough of low pressure will bring cooler
weather...a deeper marine layer...and more extensive marine clouds
for the latter half of the week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Satellite imagery this evening showed mostly clear skies across the
region. Higher clouds were moving onshore north of l... lower
clouds were gathering along the San Diego County coast. Surface
pressure gradients were trending onshore to Nevada...but holding at 6-8
mbs onshore to the lower deserts. Strongest wind gusts were mostly
under 25 miles per hour...except through the San Gorgonio Pass where gusts to
40 miles per hour were occurring.
The broad subtropical high pressure ridge along 30n today...will
drift NE and be centered over New Mexico later in the week. As the
high builds northeastward...inland areas will experience warmer days
under sunny skies until Thursday when upper-level winds switch from SW to
south and some subtropical moisture gets drawn northward across
socal. This will bring more high clouds...but at this time is not
expected to result in any shower/thunderstorm activity. It looks like the
winds aloft will not be from the south for long as a low pressure
center drifts closer to the California coast and moves onshore Friday. Any
moisture that invades the area on Thursday will be blasted eastward as
much drier air arrives on SW winds. This will also increase onshore
flow and ramp-up the marine layer over coastal areas.
Daytime temperatures are expected to peak on Wednesday...then fall off for
the remainder of the week as high clouds arrive and the marine layer
deepens. Gradual warming next week as the low moves east and
A heat advisory has been issued for portions of the Coachella Valley
Tuesday/Wednesday for high temperatures in the 112-115 range. These readings
may be achieved in the San Diego County deserts as well. Farther
west...daytime highs will be well into the 90s to near 100 in the
inland valleys...and the high deserts will see maximum temperatures
around the century mark as well Tue/Wed.
Aviation... 040300z...coast/valleys...low clouds...with bases
around 1200 feet mean sea level and tops near 1900 feet mean sea level...will continue to
develop along the coast this evening and around 20 sm inland
overnight. Visible of 2-4sm br will be possible where stratus nears
higher terrain. Low clouds and fog will clear by late Tuesday
Mtns/deserts...scattered high clouds with unrestricted visible through
Marine... 800 PM...breezy west-northwest winds 15 to 20 knots over the
outer waters each afternoon and evening through Wednesday...with
gust near 25 knots Tuesday. A Small Craft Advisory for winds has been
issued for the outer coastal waters from noon Tuesday until 11 PM
Skywarn... Skywarn activation is not requested. However weather
spotters are encouraged to report significant weather conditions.
California...heat advisory from noon Tuesday to 6 PM PDT Wednesday for
Coachella Valley-San Gorgonio Pass near Banning.
Pz...Small Craft Advisory for winds from noon to 11 PM PDT Tuesday
for waters from San Mateo Point to the Mexican border
extending 30 to 60 nm out including San Clemente Island.