Scientific Forecaster Discussion
fxus66 ksgx 151538
Area forecast discussion
National Weather Service San Diego California
838 am PDT Wed Aug 15 2018
monsoonal moisture will increase through Thursday with increasing
chances for afternoon and early evening thunderstorms in the
mountains and deserts. High pressure aloft will move westward and
over Southern California for Friday through Sunday bringing drying
and a warming trend. Minor intrusions of monsoonal moisture may
return early next week as high pressure moves back to the east.
Areas of night and morning low clouds and fog will continue for
Discussion...for extreme southwestern California including Orange...
San Diego...western Riverside and southwestern San Bernardino
The marine layer has made a courageous comeback in the last couple
days. This morning the marine inversion is stronger and likely
explains why the clear out is going slower so far. Sea surface
temperatures lately have been in the mid 70s rather than upper
70s, which likely is helping the low cloud deck to form and the
inversion to strengthen. Meanwhile, thunderstorms in Arizona last
night have sent some moisture and a few clouds in our direction
this morning, a hint of things to come. This monsoon flow from the
east will bring back a few thunderstorms mainly to our mountains
this afternoon. The easterly flow continues to add to high
moisture content Thursday and bring more thunderstorms to the
mountains and deserts too. That easterly flow could help a couple
thunderstorms drift west of the mountains into inland valleys.
Model guidance shows the marine layer seems to be largely unfazed
by this latest monsoon push, and maintains night and morning
coastal clouds getting into westernmost valleys each night. The
monsoon flow backs off on Friday for only a few thunderstorms in
the mountains. High pressure aloft strengthens a bit this weekend
while the monsoon flow backs off. That will mean higher
temperatures and a shallower marine layer, but no thunderstorms.
Next week models show some increase in monsoonal moisture, but not
very convincing to forecast much chance of thunderstorms. The
High Breaks down slightly as well, so it doesn't appear as hot but
probably more humid. Overall, minor ebbs and flows in monsoon
flow, slight variations in marine layer and coastal cloud extent,
and minor fluctuations in temperatures. In other words, seasonal
151530z...coasts/valleys...bkn-ovc015-020 at the coastal airports
through 20z, becoming scattered-bkn020 after 20z. After 03z...bkn-ovc015-
020 moving 20 miles inland through 16z Thursday, with gradual
clearing back to the coast through 21z.
Increasing mid level clouds and southeast flow above 7000 ft.
Mountains/deserts...scattered thunderstorms and rain over the mountains between 20-03z
with some storms moving into the upper deserts near Victorville and
Barstow. Reduced vis in heavy rain, and gusty sfc winds 30-40 kt
no hazardous marine weather is expected through Sunday.
south swells 3-4 feet/16-18 seconds arriving this evening bringing
elevated surf and strong rip currents Thursday into the weekend.
Surf will build to 3 to 6 ft with sets to 7 ft on south and
southwest facing beaches in Orange County and northern San Diego
County through at least Friday.
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
California...beach hazards statement from this evening through Friday evening
for Orange County coastal areas-San Diego County coastal