Scientific Forecaster Discussion
Area forecast discussion
National Weather Service San Diego California
145 PM PDT Tuesday Jul 7 2015
a low pressure centered off of the central California coast will
slowly move inland through Thursday. This feature will help to
increase onshore flow...create cooler conditions...and produce a
deep marine layer west of the mountains. In addition...clearing
will be limited at the beaches and coastal areas with drizzle
possible during the late nights and early mornings. As the system
moves east of the area Friday the weekend...expect slightly warmer
weather and a shallower marine layer.
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
according to the visible satellite image at 1 PM...inland low clouds
had eroded back to within 5 miles of the coast with mostly sunny
skies elsewhere. A 9 degree c temperature inversion...noted on the
12z morning nkx sounding...will aid in keeping low clouds from fully
scattering out along many of the coastal locations this afternoon.
Onshore surface pressure gradients remain moderately strong. For
example the gradient between san and ipl was observed at +7.5 mb.
Water vapor imagery at 100 PM PDT showed a deep closed low pressure
system spinning 350 miles west of San Francisco. This feature will
continue to influence the weather pattern across Southern California
through Thursday by deepening the marine layer...increasing onshore
flow...and creating cooler conditions over the region. Afternoon
clearing may be limited along the beaches/coastal zones and early
morning drizzle will again be possible. Winds in the mountains and
deserts will become gusty at times...reaching 30 to 40+ miles per hour in the
wind prone areas between passes...such as the San Gorgonio
Pass...and on the desert slopes. Lowering 500 mb heights and
increased onshore flow will keep conditions 10 to 20 degrees below
normal for this time of year across the inland Empire...inland
for Friday through this weekend...the aforementioned low pressure
system will slide east of the area and a weak West Coast trough
will take its place. This pattern would bring slight warming west
of the mountains...a shallower marine layer...and better afternoon
clearing of low clouds along the coast. By early to middle next
week...long range models are on agreeance of a high pressure cell
residing over New Mexico with a weak trough developing off of the
West Coast. However...the 12z GFS is a bit more aggressive on
rotating monsoonal moisture into the area by middle next week with
south/southeast flow aloft...while the 12z European model (ecmwf) remains dry.
072035z...coast/valleys...bkn-ovc stratus 1600-2000 feet mean sea level lingering
within 10 sm of the coast through 08/0200 UTC...including
ksan...ksna and kcrq...although tempo scattered-few ceilings possible for
maybe an hour or two. Sky clear and unrestricted visible elsewhere. 08/0200-
1500 UTC...overcast stratus filling in over the coast and valleys
again...with bases 1200-1600 feet mean sea level and tops 2700-3500 feet mean sea level.
Forecast confidence moderate-to-high. Slow clearing again after
Mtns/deserts...mostly sky clear with unrestricted visible through Wednesday
morning...with just some scattered-few clouds at or above 10000 feet mean sea level over the
mountain ridges and high deserts this afternoon. After 08/0000 UTC...west
winds 15-25 knots with gusts 30-35 knots over mountain ridges...through/below
passes/canyons...along desert slopes and into adjacent desert areas
will create moderate-strong uddfs/low level wind shear over and east of the mountains
135 PM...no hazardous marine weather is expected through Sunday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.