Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service San Diego California
820 PM PDT Friday Aug 29 2014
Updated aviation...marine and beach sections
weakening upper-level high pressure will allow cooling to begin
along the coast....but continue hot weather for inland areas through
Saturday. A pattern change will begin on Sunday with cooler weather
and a deeper marine layer...with even cooler conditions developing
middle to late next week.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Today was another hot day in the deserts with Palm Springs hitting
114 degrees (9 degrees above normal). Meanwhile a gradually
increasing marine inversion and onshore flow brought welcome relief
to the coast and several miles inland through the coastal valleys.
Slightly stronger onshore gradients and a slowly deepening marine
later will continue and bring pleasant weather to the coast and
similar temperatures...with more widespread stratus layer clouds
expected overnight and in the morning. For Saturday temperatures
will not cool much if at all however in the Lower Desert. Therefore
we have issued a quick update to the forecast with a bump in temperatures
for the lower deserts for Saturday. By Sunday we should see some
cooling (better to call it not quite as hot!) In those areas as
appreciable height falls finally take place on the cusp of the upper
trough from the Pacific northwest.
Previous discussion (issued at 133 PM pdt)...
At 1 PM PDT...water vapor satellite imagery displayed an upper-
level ridge centered around 175 miles west-southwest of San
Diego...and an upper-level low associated with the remnants of
Post-tropical cyclone Marie around 900 miles west of San Diego.
Visible satellite showed clear skies across southwestern
California...except for a few areas of stratus just off of the San
Diego County coast. Temperatures were a few degrees cooler along
the coast and valleys...and a few degrees warmer in the mountains
and deserts compared to this time yesterday.
The upper-level ridge will slowly flatten and traverse southwest
throughout the weekend. Although cooler weather will prevail along
the coast through the weekend as the marine layer
redevelops...warm weather will continue well inland through
Saturday...with high temperatures a few degrees above normal. A
weak shortwave trough moving southeast to our north will create
breezy westerly winds to 40 miles per hour Saturday afternoon and evening
over the high deserts.
Dry flow aloft will then transition southwesterly as a very broad
upper-level ridge develops over the southern contiguous United
States early next week. This will help create a deeper marine
layer...a weak coastal eddy and high temperatures near to and
below normal. By the middle of next week...the upper-level high
will shift more to the east as a trough digs along the West Coast.
The 29/1200 GFS and European model (ecmwf) are in good agreement with the pattern
through the middle of next week...but then diverge in agreement
next weekend in the placement of the trough in the far extended.
The likely outcome will be high temperatures 5 to 15 degrees f
below normal...a very deep marine layer...and breezy westerly
winds in the mountains and deserts to close out next work week.
Models do hint at a possible return of monsoonal moisture next
weekend over eastern Southern California as the aforementioned
upper-level high moves westward...possibly creating southeasterly
flow over the region. However...this could also be inhibited by
the trough along the West Coast if models forecast a continuance of
300300z...coast/valleys...through 30/1400 UTC...stratus with bases
800-1200 feet mean sea level and tops 1500 feet gradually spreading inland 10-15
miles. Areas of visibility 3-5 miles in higher terrain. 30/1400-1800
UTC...stratus clearing to the Coast.
Mountains/deserts...mostly clear skies and unrestricted visibility
through Saturday morning.
815 PM...no hazardous marine weather expected through Tuesday.
815 PM...coastal reports show that the surf conditions have fallen
below high surf advisory levels. The high surf advisory expired at 8
The southerly swell will continue to diminish through the long
Holiday weekend. However...there will still be occasional rip
currents at the beaches. Swimmers are encouraged to always swim near
spotter activation will not be needed this weekend.