Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 191022

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
322 AM PDT Sun Sep 19 2021

.SYNOPSIS...18/814 PM.

Below normal temperatures are expected through the weekend, with
low clouds and fog over most coastal and valley areas. Gusty north
winds are expected later Sunday over Santa Barbara County as well
as northern Los Angeles County. Breezy offshore flow will form
Monday and Tuesday. Warmer and drier conditions with fewer marine
layer clouds will result Monday and last through the middle of the


.SHORT TERM (TDY-TUE)...19/307 AM.

Decent north push occuring over the area. The north flow has
filled the Central Coast and the interior SLO vly with low clouds,
but at the same time has prevented much of any low clouds south of
Pt Conception. High temperatures will cool across the interior as
the north flow brings in cooler air from the interior. But the
north flow will bring a substantial 3 to 6 degree warm up over the
coasts and vlys (except for the San Gabriel Vly and LGB area which
will not feel the effects and will cool a few degrees). Gusty
west to northwest winds will likely occur this afternoon and
evening across the Antelope Valley and Interstate 5 corridor.

The sundowner winds are expected to strengthen this evening as
both the KSMX-KSBA and KBFL-KSBA gradients are expected to peak
around -4 mb. This along with increasing upper level winds will
likely generate advisory level gusts across most of the SBA south
coast with the strongest gust (50 mph) near Gaviota/Refugio.

Big time warming slated for Monday. Hgts will rise to 591 dam as
an upper high pushes in from the SW. 2 to 3 MB of offshore flow in
the morning will keep the marine layer at bay and will also delay
or eliminate the sea breeze. Not expecting advisory level winds
but there should be 15 to 25 mph NE canyon winds across the LA/VTA
county area in the morning. The rising hgts, abundant sunshine and
offshore flow will all combine to bring 8 to 12 degrees of warming
to the area. The only exception will be the SBA south coast where
there will be cooling due the lack of north winds.

Tuesday will be the warmest day for all of the area except for the
Central Coast and the SBA south coast. The day will start off with
low clouds across the Central Coast and perhaps the Long
Beach/Torrance area as well as easterly winds across the most of
LA/VTA counties and eastern SBA county. The marine layer will
bring double digit cooling to the Central Coast but the east flow
will be 2 to 4 degrees of warming to most of LA/VTA counties as
well as the interior SLO and SBA counties. Aside from the Central
Coast and SBA south coast which will be 2 or 3 degrees blo normal
the rest of the area will end up 4 to 8 degrees above normal.

.LONG TERM (WED-SAT)...19/321 AM.

Wednesday will be a transitional day as the upper high pushes off
to the east and a trof arrives from the NW. Hgts will fall slowly
through the day but will still end up above normal at 591 dam.
There will be increasing onshore flow and the marine layer stratus
should return to the near shore areas (Hgts start out at 594 dam
which will smoosh the marine to under 600 ft) Most of the SLO and
SBA counties will cool as the hgts fall. There will likely be no
change or even a little warming for areas south of Pt Conception.

Two days of widespread cooling are expected on Thursday and
Friday as an upper-level trof, or even a cutoff low (EC), moves
down the west coast to around San Francisco on Thursday. It moves
west and deepens briefly on Friday before shooting off to the
northeast. Lower heights and more onshore flow will bring more
stratus to the coasts and some of the lower valleys. Max temps
will fall each day.

The EC and GFS are massively out of sync on Saturday. The EC
forecasts an upper low while the GFS has an upper high. The
ensembles are all over the place as well but seem to slightly
favor the warmer GFS (but most are cooler than the deterministic
GFS soln) The forecast has a little warming trend but really do
not have much confidence in the forecast and expect to see a
different set of solutions in 24 hours.



At 0505Z at KLAX, the marine layer was 1400 feet deep. The top of
the inversion was 2200 feet with a temperature of 22 C.

Very good confidence in TAFs for KPMD, KWJF, KSBP and KSMX.

Good Confidence in TAFs for KSBA, KCMA, KBUR and KVNY with a 30
percent chc of OVC010 conds 13Z-17Z

Moderate confidence in remaining TAFs as flight cat changes could
be off by +/- 90 minutes. There is a 20 percent chc of IFR cigs

KLAX...Moderate confidence in TAF. Arrival time of low clouds
could be any time 10Z-13Z. There is a 20 percent chc of OVC008
12Z-16Z. VFR transition could be as late as 18Z. No significant
easterly wind component expected.

KBUR...Good confidence in TAF. There is a 30% chance of OVC010


.MARINE...19/131 AM.

Northwest winds will continue to increase from the Central Coast
to San Nicolas Island through today, with Small Craft Advisory
(SCA) conditions expected over the outer waters through Monday
evening, and over the western portion of the Santa Barbara Channel
and inner waters N of Point Sal this afternoon and this evening.
Widespread steep and choppy seas will result from these winds over
much of the coastal waters. Much lighter winds and lowering seas
are likely Monday and Tuesday. There is a 10 percent chance of
15-20 KT Santa Ana winds affecting the coastal waters south of
Ventura on Monday or Tuesday. If these winds form, high confidence
that they will NOT affect Catalina. Winds and seas should remain
below SCA levels Wednesday and Thursday. Dense fog and low
visibilities are possible Monday through Wednesday.


PZ...Small Craft Advisory in effect from 3 PM this afternoon to 11
      PM PDT this evening for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT Monday for
      zones 670-673-676. (See LAXMWWLOX).



Elevated fire weather conditions are expected through Tuesday
with dry air and gusty offshore flow.



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