Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
559 PM PDT sun may 24 2015
Just sent a quick update to the forecast to account for the rapid
clearing of marine stratus across the coast and through the valleys.
00z sounding shows a deep and strong marine layer with Delta T about
11c and height of marine layer around 5000 feet mean sea level. Marine stratus is
expected to push back in late tonight. No other changes at this time.
Low pressure aloft will continue a fairly deep marine layer...along
with abundant marine clouds at times through Wednesday. Gradual
warming each day...especially inland with better daytime clearing.
Much warmer inland during the latter half of the week as high
pressure builds aloft.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
Visible satellite imagery early this afternoon indicated little
clearing over the coastal basin...while skies were mostly clear over
the deserts. Surface pressure gradients were running around 5 mbs to
the deserts at midday with some wind gusts still over 35 miles per hour through
the windiest corridors into the deserts. Elsewhere...wind peak gusts
were mostly under 25 miles per hour.
Looks like only partial clearing at best west of the mountains for the
remainder of the day due to the deep moist layer. Overnight...
expect the clouds to remain...keeping overnight minimums on the mild
side. Over the deserts...the clear skies and lighter winds should
allow temperatures to drop off few more degrees tonight than last
The 12z GFS/European model (ecmwf) runs are in agreement with the overall 500 mb
pattern across the west this week. The compact area of low pressure
over the lower Colorado River valley will swing east on Monday...
allowing heights to rise modestly before another broad...weak upper-
level trough develops over the west. Little cooling will accompany
this trough..but it should hold onshore flow and a moderate marine
influence west of the mts. East of the mts...the deserts will warm
back to seasonal (or higher) daytime temperatures. This puts the
high deserts into the 90s and the lower deserts around the century
mark by Friday.
Both the GFS/ec model solutions continue to build heights over the
area next weekend which will push temperatures above average into
next week...especially just inland from the coast. A shallow marine
layer and onshore flow should keep the coastal strip more moderate
with areas of night and morning low clouds and fog.
Aviation... 242010z...coast...valleys...coastal slopes...and Santa
Ana Mountains...ovc-bkn clouds with bases 3000 feet mean sea level...tops 4500-5000 feet
mean sea level and mountain obscuration likely not clearing much through 25/0200
UTC. 25/0200-1500 UTC...bkn-ovc stratus re-developing...with bases
2000-2500 feet mean sea level and tops around 4000 feet mean sea level...with mountain obscuration
continuing. Moderate-to-high forecast confidence. Marine layer
inversion of about 4-5 degree c expected. Any clearing tomorrow will be
partial and gradual during the late morning/afternoon hours.
Mountain ridges...deserts and desert slopes...unrestricted visible and mostly
sky clear through Monday morning.
Marine... 110 PM...no hazardous marine weather is expected through
Beaches... 110 PM...nearshore buoys indicate that the long-period
south swell arrived earlier today. The swell will build today...peak
Monday at 3 feet/16 seconds...and subside Tuesday into Wednesday.
These swells will likely produce strong rip and longshore currents
today through Monday...with some elevated surf in Orange County and
northern San Diego County. See the beach hazards statement for
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...beach hazards statement through Monday evening for Orange County
coastal areas-San Diego County coastal areas.