Scientific Forecaster Discussion
Southwest California area forecast discussion...update
National Weather Service Los Angeles/Oxnard California
430 PM PST Sat Nov 22 2014
..updated aviation discussion...
Expect for some clouds slight chance of showers this evening across
the North Mountain slopes...skies will remain mostly clear through
next week. Offshore winds will persist through at least middle week and
will allow for warmer than normal temperatures for coast and
valleys. Some cooling is expected late next week.
Short term (today-wed)...
the front was pretty much a no show today...it barely even managed
to produce any clouds. Today temperatures are similar to ydys across vta
and la counties but there was a fair amount of warming across the
central coast. Everything now is about the winds. Current pressure
grads are running west to east and the Antelope Valley is seeing advisory
level gusts along some areas of blowing dust. This evening the
gradients will shift to the north and will combine with weak cold
air advection to bring advisory level gusts to the sba South
Coast...the la and vta mountains (esp the i0-5 corridor)...the Santa
Monica Mountains...and the valleys about 20 miles either side of the la/vta
County line. These north winds will also pile up a bunch of clouds
along north slopes of the la/vta mountains as well as the Cuyama Valley.
The upslope will also allow for a slight chance of a showers through
early Sunday morning
On Sunday the surface high builds into Nevada and sets up a northeast
pressure gradient. There is not that much upper support. The winds
across the sba South Coast will shut off. But all of the NE oriented
passes and canyons will light up with low end advisory level gusts.
The Ventura County coast will flirt with advisory level winds but
they should remain just under. The winds will lull in the afternoon
as the pressure pattern reaches its diurnal minimum. The cool air
advection will decrease the maximum temperatures Sunday in he interior but the
offshore flow will warm temperatures from todays values across the coasts
Clear skies dry winds will allow for very cool overnight lows in the
wind sheltered areas. Windier areas will have warmer than normal
lows as the breezes keep the low levels of the atmosphere mixed up.
The interior valleys of slo and sba counties as well as the Antelope
Valley will have another round of freezing or near freezing temperatures.
The surface gradients weaken on Monday and the current wind advisories
may be overkill. There is no upper or thermal support either so
future shifts will have to take a hard look at these winds. Very low
end advisories at worst. Otherwise a sunny day with above normal
temperatures. Heights rise to 583 dm and offshore flow persists. Maximum temperatures
will jump into the upper 70s and lower 80s across most of the coasts
Models showing a pretty strong east wind event for Tuesday as the surface
high moves southward into Nevada. Winds through 700 mb turn easterly
as well. Its still early but this could be a decent event. Avalon
Harbor residents should keep an ear turned to the weather news. If
the NAM is correct the areas prone to east winds will see the
strongest winds of the week. Still the NAM likes to over do wind
speeds so its not a slam dunk forecast. It will be sunny and plenty warm
with as wide swath of maximum temperatures in the middle 80s.
Wednesday will be just like Tuesday except a little less windy and little
warmer as the surface grads relax (but remain offshore) and The Heights
rise to 588 dm as the ridge axis moves over California. Right now
have plenty of middle to upper 80s in the forecast but would not be
surprised to see some 90 degrees readings.
Long term (thu-sat)...
both GFS and ec agree that the ridge will slowly push to the east
Thursday and Friday. More importantly the offshore flow relaxes. Skies will
remain mostly clear. Maximum temperatures will cool a little each day (more
than a little right at the coast) but will remain above normal.
Saturdays forecast is questionable the ec brings in a slight ridge
while the GFS brings a trough to the east Pacific. Did not really bite
hard on either solution and just trended the forecast cooler and a little
At 2330z...there was no marine inversion at klax.
Generally hi confidence overall in the 00z tafs. VFR conditions are
expected through sun at ksba...koxr...klax...klgb...kbur...kvny...kwjf
anf kpmd. For kprb...there is a 30-40 percent chance of MVFR ceilings
this evening...otherwise there is generally hi confidence in the 00z
taf with VFR conditions through sun. For ksbp and ksmx...MVFR ceilings are
expected this evening through about 03z-04z...but the timing of the low
clouds dissipating may be off plus/minus an hour or so. Otherwise
VFR conditions will prevail at the airfields through sun. Low level
wind shear is expected at ksba from 02z-13z sun due to gusty North
Canyon winds in the vicinity. Gusty north winds should affect kbur and
especially kvny late tonight and sun...with a 20 percent chance of
low level wind shear at times at kbur. There will be gusty west to northwest
winds at kpmd and kwjf this evening...then turn NE on sun and become
gusty in the afternoon. Brief periods of reduced visibilities in blowing
dust will be possible through early this evening at these airfields as
Klax...hi confidence in the 00z taf with VFR conditions expected
through sun evening. North to NE winds less than 10 knots are expected from
about 05z to 20z sun.
Kbur...hi confidence in the 00z taf with VFR conditions expected
through Sun afternoon. North winds gusting to 15 knots will be possible
from about 14z-21z sun...with a 20 percent chance of low level wind
shear at times.
Marine...22/200 PM PST...
North and northwest winds will likely strengthen and create Small
Craft Advisory conditions over the outer waters from San Clemente
Island to San Miguel Island through this evening. Small Craft Advisory conditions
will persist through Sunday night as well but the winds will become
northeast over the central portion Sunday morning through early
afternoon and then north winds will likely strengthen over the
northern portion Sunday afternoon. Northwest winds will likely
create Small Craft Advisory conditions over the Santa Barbara Channel this afternoon
and persist through late tonight. It is likely Small Craft Advisory conditions will
develop near shore from Ventura Harbor to Santa Monica and extend
out to Santa Cruz Island Sunday morning. Seas generated over the
eastern Pacific within 290-300 degrees relative to the area will
arrive this evening and create Small Craft Advisory conditions for hazardous seas
along the central coast and extending south to San Clemente Island
through Sunday night.
red flag warning (see laxrfwlox).
Fire Weather Watch (see laxrfwlox).
Wind Advisory (see laxnpwlox).
Small Craft Advisory (see laxmwwlox).
High rip current risk (see laxsrflox).