Gale Warning 37, NWS Los Angeles, CA

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
116 PM PDT Thu Aug 27 2020

.SYNOPSIS...27/115 PM.

A cooling trend will develop for the weekend and near normal
temperatures are likely late this weekend or early next week,
followed by a warming trend to above normal away from the coast
by mid week. Breezy northerly winds will affect southern Santa
Barbara County this evening through early Friday morning.

&&

.SHORT TERM (TDY-SUN)...27/113 PM.

Patchy low clouds lingered along a few of Central Coast beaches
early this afternoon. Otherwise, sunny skies covered the forecast
area, with little change expected thru sunset. Temps this
afternoon are forecast to be several degrees above normal away
from the coast, with the valleys and lower mtns rising into the
upper 90s to 103. As a result, a Heat Advisory is in effect thru 9
PM this evening for many areas of L.A. County away from the
coast. Please see the latest Non-Precipitation Weather Message
(LAXNPWLOX) for the latest info on the Heat Advisories.

An upper level high near the Four Corners region today will drift to
the SE into W Texas and New Mexico Fri into Sat. At the same time,
upper level troffiness will persist along and just off the central
and SW CA coast, with a broad and dry SW flow aloft over the
forecast area. The upper level high is forecast to drift S into
northern Mexico by Sun, with upper level troffiness lingering
over swrn CA.

The marine inversion should not change much for tonight thru Sun
and be generally around 1200-1400 ft deep along the Central
Coast, and about 600-1000 ft deep south of point Conception.
Night and morning low clouds and fog are expected to affect the
Central Coast, Santa Ynez Vly, Salinas River Vly and L.A. County
coast tonight, then expand to cover mainly the coastal plain and
some lower adjacent vlys Fri night thru Sun morning. Otherwise,
mostly clear skies will prevail across the region thru Sun. Temps
are forecast to lower gradually thru the period, but remain a few
degrees above normal for inland sections except cooling to
slightly below normal for the vlys closer to the coast by Sat.
Gusty N canyon winds will affect the SBA County S coast and mtns
tonight thanks to good offshore flow (NAM fcst SBA-SMX gradients
of -3.5 mb at 06Z this evening), with gusts approaching advisory
levels at times. Otherwise, there should be typical onshore flow
each afternoon and evening across the region thru Sun, with breezy
to gusty S-W winds especially along the Central Coast and in the
foothills, mtns and deserts.

.LONG TERM (MON-THU)...27/113 PM.

The EC and GFS are in good agreement thru Tue with upper level
troffiness wakening Mon and upper level ridging nosing into the
area from the N on Tue. For Wed and Thu, the EC forecasts the
upper ridging to strengthen into an 595 dm upper level high over
central and srn CA, while the GFS builds a weaker upper level high
more into the central and southern Great Basin, with very weak
upper troffiness over the forecast area. It does look like either
model solution will heat things up over the region by mid week.

Overall, little change in the general weather pattern can be
expected over the region during the extended period, with varying
amounts of night and morning low clouds and fog persisting mainly
along the coast, except into some adjacent vlys Mon. Temps are
forecast to become several degrees above normal by Tue and
continue thru Thu, with the hottest inland locations reaching the
low 100s. The typical afternoon and early evening onshore flow
pattern will persist as well, except some sundowner winds will be
possible over southern SBA County during the evening hours
starting Tue.

&&

.AVIATION...27/1908Z.

At 1739Z at KLAX, the marine layer was about 600 feet deep. The
top of the inversion was at 2200 feet with a temp of 28C.

Moderate confidence in the 18z forecast. Low clouds are expected
to become widespread tonight on the Central Coast, in the Santa
Ynez Valley, then in the Salinas Valley late, with LIFR to VLIFR
conds expected. Low clouds are also expected across the L.A.
County coastal plain with generally IFR conditions expected.

KLAX...Moderate confidence in the 18z TAF. There is a 20-30%
chance that skies will remain clear tonight.

KBUR...High confidence in the 12z TAF, with CAVU conds thru the pd.

&&

.MARINE...27/112 PM.

Overall, moderate confidence in forecast. Small Craft Advisory
(SCA) level winds will likely continue across the outer waters
through late tonight. Local gale force gusts continue and are a
bit troubling considering model data does not support winds that
strong. Will add a Gale Warning for zones 673 and 676 through
tonight. After tonight, conds will likely remain below SCA levels
Fri through Mon. However, seas will remain rough and choppy with
short periods Fri and Fri night.

Across the inner waters north of Pt. Sal, SCA level NW winds are
likely this afternoon and evening, then conds are expected to
remain below SCA levels tonight through Mon.

Across the inner waters south of Pt. Conception, choppy short
period seas will be close to SCA levels in some areas this
morning. SCA level winds and seas are likely across western
portions of the Santa Barbara Channel this afternoon through late
tonight. Elsewhere, there will be local gusts to 20 kt this
afternoon and evening. After tonight, conds are expected to remain
below SCA levels through Mon.

Patchy dense fog with visibility 1 nm or less will likely affect
portions of the coastal waters this morning.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 9 PM PDT this evening for zones
      46-54-88-547. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 650-670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SUN-THU).

No significant hazards expected.

&&

PUBLIC...Sirard
AVIATION...Sweet/DB
MARINE...Sweet
SYNOPSIS...Sirard

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