Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 230417
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
817 PM PST Mon Jan 22 2018

.SYNOPSIS...
Offshore flow and a building upper level ridge will bring a few
days of warming to the region. An upper level trough
will swing a weak front into the area Wednesday night into
Thursday allowing for a chance of light showers across the
northern portion of the forecast area, with only a slight chance
to the south. Strong ridge will build in this weekend bringign
very war and dry conditions.

&&

.SHORT TERM...(MON-THU)

Latest GOES-16 satellite imagery indicated mostly clear skies
across the forecast area with the exception of some remnants from
a dying frontal boundary across the coastal waters N of Point
Conception and some low clouds developing across the Central
Coast and into portions of the Santa Ynez Valley. With the passage
of the dying front, northerly wind gradients have developed this
evening. LAX-BFL was at -4.2mb and should peak around -4.5mb late
tonight. Low clouds across the Central Coast should scour out
early tomorrow morning due to offshore flow, but could linger
across a few locations through mid morning. As far as winds, the
usual wind prone areas including the SBA/VTU/LA County Mtns were
remaining below wind advisory thresholds, but as usual the one
outlier is Whitaker Peak near Lake Castaic gusting at 58 mph,
while the few other mountain sites were gusting around 35 mph.
Some of the gusty winds have filtered into the Santa Clarita, San
Fernando Valley. Not anticipating any widespread freeze issues
tonight due to the wind mixing the air near the surface. However,
there will be some wind protected areas around the Central Coast
that will near freezing. The northerly gradients will shift to the
northeast as a 1034 mb high sets up over Nrn Utah in the morning.
Weak to locally moderate Santa Ana winds will develop early Tue
morning. There could be some local gusty winds reaching advisory
levels in the mountains and a few of the wind prone valley passes
and canyons for LA/VTU Counties tomorrow morning.

High temps will rebound nicely tomorrow due to the offshore flow,
especially across coast and valleys, but most all areas will
experience some warming including the Antelope Valley, which
usually sees a few degrees of cooling with this type of scenario.
Highs generally 4-10 degrees warmer Tuesday. Highs will continue
to trend higher a few degrees across the interior areas including
the mountains and the Antelope Valley while the coastal areas see
a degree or two of cooling from the return of the afternoon
seabreeze. Expect LA/Ventura county coast/valleys to warm into the
70s and 80s Tue/Wed.

***From Previous Discussion***

The tail end of another system will hit the northern areas late
Wednesday into early Thursday. This one seems to have slightly
more staying power to it so confidence is higher that we`ll
actually see some measurable precip from it, albeit still quite
light and virtually all of it north of Pt Conception. There could
be a few sprinkles or very light showers as far south as Santa
Barbara very early Thursday morning but there`s too much
west/northwest flow with it to allow much of that precip to reach
the ground. Otherwise expecting clearing skies Thursday with again
some increasing north to northwest winds behind it Thursday
evening. Daytime temps will drop several degrees as well Thursday
with the frontal passage with highs mostly in the 60s at lower
elevations.

.LONG TERM...(FRI-MON)

A pretty strong high pressure ridge is expected to develop along
the west coast behind the Thursday frontal passage and last
through the weekend. Gradients will shift back to offshore, which
combined with the high pressure aloft will push temps back up to
the 70s and 80s for coast/valleys south of Pt Conception and
60s/70s up north. Not really looking for any winds of significance
except some gusty north to northeast winds through the Santa Ynez
and Santa Lucia ranges Friday night into early Saturday.

This pattern breaks down somewhat early next week but only enough
to cool things off as the trough that`s coming is expected to take
an inland path through the west and likely initiate another
offshore flow pattern that will last through at least the middle
of next week. It`s looking increasingly likely that the southern
part of the forecast area will remain dry through the remainder of
January.

&&

.AVIATION...23/0300Z.

Due to Government shutdown, AMDAR data was not avail.

High confidence in CAVU TAFs except for the Central Coast where
MVFR/IFR and possibly LIFR cigs will occur through at least 10z.
Weak offshore flow should scour out stratus by 10z, but 40%
chance that IFR/MVFR cigs could linger through 17z.

KLAX and KBUR...High Confidence in CAVU TAF.

&&

.MARINE...22/800 PM.

Across the southern outer waters zones (PZZ673, PZZ676) SCA conds
for seas are expected through Tuesday afternoon due to a
combination of gusty north winds and high seas.

Across the northern outer waters zone (PZZ670) SCA conds are
likely to continue through Tuesday afternoon due to high seas.
SCA seas will persist through late tonight in the nearshore
waters north of Point Sal (PZZ645).

Across the SBA Channel and the southern inner Waters, SCA conds
are not expected until Thursday.

Another long period swell is expected Thursday into Friday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 11 AM PST Tuesday for
      zones 34-35. (See LAXCFWLOX).
PZ...Small Craft Advisory for hazardous seas in effect until 4 AM
      PST Tuesday for zones 645-670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PST Tuesday for
      zones 673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(THU-MON)
Gusty winds are possible Thursday and Friday over the mountains
and southern Santa Barbara County. Gusty Santa Ana winds could
develop over next weekend.

&&

$$

PUBLIC...Kaplan/MW
AVIATION...Kaplan
MARINE...Smith
SYNOPSIS...STu

weather.gov/losangeles



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