Gale Warning 34, NWS Los Angeles, CA

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1023 PM PST Thu Dec 5 2019

.SYNOPSIS...05/746 PM.

Clouds will increase tomorrow as the next storm system approaches
bringing gusty winds and rain to San Luis Obispo County as early
as Friday morning, and into the remaining counties by Friday
night. The chance of rain will persist through Saturday, with
lingering showers possible early Sunday. Temperatures will begin
warming through Thursday as high pressure returns.

&&

.SHORT TERM (THU-SUN)...05/835 PM.

***UPDATE***

An upper level ridge over srn CA this evening will slowly move E
of the region overnight while an upper level low and its
associated large upper level trof over the E Pac slowly edges E.
Lingering low level moisture will keep varying amounts of
stratocu over portions of the forecast area overnight. There is
also plenty of hi clouds streaming into the region from the SW
this evening which will continue overnight. Overall, mostly cloudy
skies will prevail across the region tonight. Some offshore flow
will develop overnight specially over portions of VTU/L.A.
Counties but winds will be well below advisory levels. With the
clouds and breezes, overngiht low temps are expected to be mild
and significantly above normal.

***From Previous Discussion***

A very similar scenario Friday though models are a little less
moist in the lower levels than today. May see a little more
sunshine but still on the cool side. An upper low is spinning
around near 40n/140w and will only move very slowly east through
Saturday as it bumps into a weak upper ridge along the coast. We
will see moisture increasing across the area Friday night with
rain becoming increasingly likely across all of SLO/SB Counties.
And by Saturday morning or afternoon light showers should reach
most of LA County except possibly the Antelope Valley.

A second impulse will follow Sat night into Sunday morning
maintaining a good chance of precip most areas through the
weekend.

Since the upper low is expected to stay well to the north the
impacts this far south are expected to be minimal and rain
amounts and rates, except for the NW SLO hills, are expected to
be on the light side. Most areas will total under an inch with
rates typically less than .1"/hr. LA County will see the lowest
amounts, generally a half inch or less. Once again this will be a
high snow level event, hovering around 8000' Sat then lowering to
between 6000-7000' Sun.

.LONG TERM (MON-THU)...05/144 PM.

The trough is expected to move east late Sunday and Monday with
dry and warmer conditions early next week as a ridge of high
pressure moves over the west coast.

The ridge will break down Wednesday as a weak trough approaches
from the west. We'll likely see some clouds from it and a slight
cool down but no precip.

Models now in near unanimous agreement on a very strong high
pressure ridge developing over the eastern Pacific Thursday and
expanding east through Saturday. This will maintain dry weather
through the week and likely some warming, but nothing dramatic as
gradients are only lightly offshore at most and 950mb temps stay
below 20c.

&&

.AVIATION...06/0618Z.

At 05Z, there was no marine inversion at KLAX, but there was a
deep moist layer up to around 4500 feet.

Low-to-moderate confidence in the current forecast. MVFR to VFR
conditions with ceilings at or below 6000 feet will become
prevalent through 13Z. There is a chance of VLIFR to LIFR
conditions in ground fog between 10Z and 16Z.

KLAX...There is a 70 percent chance of MVFR to VFR conditions
with ceilings at or below 6000 feet after 10Z. There is a 30
percent chance of VLIFR to LIFR conditions in ground fog between
10Z and 16Z. East winds greater than 7 knots will likely develop
between 02Z and 07Z.

KBUR...There is a 80 percent chance of MVFR to VFR conditions
with ceilings at or below 6000 feet after 10Z. There is a 30
percent chance of VLIFR to LIFR conditions in ground fog between
10Z and 16Z.

&&

.MARINE...05/808 PM.

For the Outer Waters, moderate to high confidence in current forecast.
For PZZ670 and PZZ673, high confidence in Small Craft Advisory
(SCA) level southeast winds and seas developing on Friday and
continuing through Saturday with a 50% chance of Gale force gusts
Friday afternoon and Friday night (GALE WATCH remains in effect).
For Saturday night and Sunday, there is a 50% chance of SCA level
winds continuing. For PZZ676, there is a 50-60% chance of SCA
level winds Friday through Saturday (especially Friday). For
Saturday night and Sunday, there is a 50% chance of SCA level
conditions.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. High confidence in SCA level winds
and seas developing Friday and continuing through Saturday with a
50% chance of Gale force winds on Friday (GALE WATCH will remain
in effect). For Saturday through Tuesday, high confidence in
conditions remaining below SCA levels.

For the Inner Waters south of Point Conception, moderate to high
confidence in current forecast. Overall, high confidence in
conditions generally remaining below SCA levels. The only
exception will be the western half of the Santa Barbara Channel
where there is a 50% chance of SCA level southeast winds Friday
and Saturday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 3 AM to 3 PM PST Friday
      for zone 645. (See LAXMWWLOX).
     Gale Watch in effect from Friday afternoon through late
      Friday night for zones 645-670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PST Friday for
      zones 670-673. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

Strong rip currents and high surf are possible at area beaches
over the weekend.

&&

PUBLIC...MW/Sirard
AVIATION...Hall
MARINE...RAT
SYNOPSIS...Phillips

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