Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
930 PM PDT Tuesday Sep 1 2015
an upper-level trough along the West Coast will continue fair and
cooler weather this week...with night and morning coastal low clouds
extending well into the valleys. Locally gusty west winds will
develop each afternoon and evening along Desert Mountain slopes and
through mountain passes. Slightly warmer weather will occur this
weekend...with a more shallow marine layer.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Areas of low clouds were along the coast with quite a lot of high
clouds over the region...associated with a low off the coast. Marine
inversion base was around 2100 feet. A little bit of an eddy
continues...but weaker than the one Monday night. High clouds will
continue to drift over the region the rest of the night...with low
clouds spreading into the valleys.
The low pressure trough will continue to deep over the West Coast
the next few days...absorbing the upper low about 300 miles off the
coast. The moisture with that upper low is above 500 mb...so no
precipitation should occur with that. Temperatures will continue to
lower the next few days and could get as much as 10-15 degree f below
normal in the valleys for maximum temperatures...though less in other
areas...and min temperatures will stay a little above normal near the coast
due to sea surface temperatures 3-5 degree f above normal. There will
be a coastal eddy at times...especially Thu/Fri...and that will
combine with lower heights to deepen the marine further then. There
could potentially be local drizzle west of the mountains by Friday
morning with the marine layer likely being 3000-3500 feet deep with
an eddy. Due to the onshore flow and thermal gradient between the
valleys and deserts...winds will gust over 40 miles per hour at times on the
desert slopes/foothills...including San Gorgonio Pass. Highest winds
will be Thu/Fri.
Most model solutions have the trough weakening over the
weekend...but with some long-wave troughing continuing...so while
temperatures will increase some...maximum temperatures will stay near or a little
below seasonal normals. Monsoonal moisture will stay south and east
of the area through at least early next week.
020300z...coast/valleys... low clouds will slowly develop over the
coast...valleys and inland Empire through 13z Wednesday. Cloud bases
will be between 1700 and 2200 feet mean sea level...with tops near 2900 feet mean sea level.
Sub 3 sm visible will occur where low clouds intersect terrain. Expect
low clouds to scattered back to the coast between 16z and 18z Wednesday.
Additional broken to scattered high cloud cover at or above 20000 feet mean sea level will
continue through 00z Thursday. A few low clouds may linger along the
coast and light sea breezes will prevail at the coastal taf sites
between 18z Wednesday and 00z thrusday.
Mtns/deserts...scattered to broken clouds at or above 20000 feet mean sea level...with
unrestricted visible through 06z Thursday.
800 PM...no hazardous marine weather is expected through Sunday
800 PM... a mix of southwest swells from hurricane activity over the
tropics will continue at local beaches through the day on
Wednesday...producing elevated surf and strong rip currents. The
highest surf of 3-4 feet will occur tonight and Wednesday with maximum
sets to 5 feet along southwest facing beaches north of Oceanside. The
southerly swell will subside some Thursday through early
Saturday..before a long period southern hemisphere swell arrives at
local beaches early next week.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.