Area Forecast Discussion
Issued by NWS Los Angeles, CA

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FXUS66 KLOX 272111
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
211 PM PDT Sun May 27 2018

.SYNOPSIS...27/1042 AM.

A weak ridge building in aloft will support a warming trend through
Tuesday with less in the way of night to morning low clouds
across coastal areas. A trough of low pressure pushing into the
West Coast will support a return to more widespread night to
morning low clouds with cooler conditions by Thursday.

&&

.SHORT TERM (TDY-WED)...27/159 PM.

Its mostly clear and 72 degrees in downtown Los Angeles right now,
on its way to a near-normal afternoon high. The winds will pick
up again this afternoon on the Santa Barbara south coast, but
should remain below advisory strength.

Looking at the big picture, there is an area of closed circulation
around a low pressure system near the northern Nevada-Utah border.
The LOX area is at the southern extent of the cyclonic flow around
this system and will see upper level winds shifting from the
northwest to more of a westerly flow as the system continues to
move off to the east. Heights will rise from 578DM today to about
583DM on Monday and Tuesday bringing warming, especially to
interior areas away from the sea breeze.

The LAX-DAG gradient remains about the same tomorrow and Tuesday
so the sea breeze should be roughly the same as today`s. However,
the increased sunshine and heights will cause high temps to trend
higher. Downtown LA should be in the high 70s by Tuesday and the
Antelope Valley and norther SLO County will be in the mid-90s.

The marine layer was around 2500 ft deep this morning with a very
weak inversion. Expect night through morning low clouds to
continue through Tuesday, but the marine layer depth should lower
to around 1500 ft Monday and below 1000 ft on Tuesday.  With the
stronger inversion expected, low clouds should become more
organized and may not scour out to the coast until early afternoon
hours.

Another broad upper level trough will deepen as it approaches the
California Coast Tuesday night into Wednesday. 500mb heights will
drop from 583 DM on Tue to 575 DM by Wednesday night. Strong
onshore winds will accompany the trough as models forecast a
gradient over 7 mb. Winds advisories are likely for Wednesday and
Thursday.  Expect significant cooling from Tuesday to Wednesday.

.LONG TERM (THU-SUN)...27/210 PM.

The coolest day should be on Thursday with the trof axis over the
region and a deep marine layer in place. Clouds should linger
well into the afternoon hours with a possible reverse clearing
scenario. High temps will be below normal.

The models diverge on Friday as the GFS continues to develop the
trough into a cutoff low system to our south which quickly
transitions to the east and lets ridging return by Sunday. The EC
keeps a more broad trough over the area through Monday. Splitting
the difference led to the forecast with seasonal temperatures. If
that pop up ridge does develop then is could be considerably
warmer next weekend that the current forecast.

&&

.AVIATION...27/1802Z.

At 1700z AT KLAX, the marine layer depth was 2200 feet. The top
of the very weak inversion was at 5600 feet with a temperature of
10C.

North of Pt Conception...widespread low clouds are expected on
the Central Coast and in the Santa Ynez and Salinas Valleys
tonight, with low MVFR to IFR conds expected. There is a 30%
chance of LIFR conditions forming at KSMX and KPRB.

S of Pt Conception...widespread low clouds tonight, with
generally MVFR conds. There is a 30% chance of IFR conditions
forming, especially for Ventura Co. sites and KSBA. Timing of cigs
forming and dissipation may differ by up to 2 hrs from taf times.

KLAX...Moderate to high confidence in the 18z TAF. Timing of MVFR
cigs moving over the site may differ by up to 2 hrs from taf
time. High confidence that easterly winds between 12-18z remain
below 8 kt.

KBUR...Moderate confidence in 18z TAF. There is a 20-30% chance
that VFR conds will persist through at least 12Z Monday. There is
a 20% chance that cigs dip into the IFR category overnight.

&&

.MARINE...27/1254 PM.

Across the outer waters, high confidence in SCA conds through
late tonight. Conditions are expected to remain below SCA levels
Monday through Monday night, with a 40% chance of SCA level winds
across the northern two outer waters zones Tuesday afternoon and
night. SCA conds are likely across all the outer waters Wednesday
through Friday.

Across the northern inner waters, there is a 40% chance of SCA
level winds late this afternoon and evening. Otherwise, SCA
conditions are not expected through Wednesday morning, with SCA
level winds likely late Wednesday afternoon through Friday.

Across the inner waters south of Pt Conception, SCA conditions
are not expected thru Wed night. There is a 40% chance of SCA
winds Thursday and Friday.

Choppy short period seas will continue through the holiday weekend
but should slowly subside.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Monday for
      zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (WED-SUN).

Strong rip currents and elevated surf could develop at Central
Coast beaches late Tuesday through early next Thursday.

&&

$$

PUBLIC...jld
AVIATION...Smith
MARINE...Smith
SYNOPSIS...Munroe

weather.gov/losangeles


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