Area Forecast Discussion
Issued by NWS Los Angeles, CA

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852
FXUS66 KLOX 212315
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
415 PM PDT Sun Apr 21 2019

.SYNOPSIS...21/142 PM.

Continued cool today then significant warming beginning Monday
and through mid week. Afternoon temperatures will cool a bit by
the weekend but will remain above normal.

&&

.SHORT TERM (TDY-WED)...21/145 PM.

Afternoon visible imagery shows stratocumulus clouds lingering
over some of the valleys and foothills south of Point Conception
with clear skies further north. An upper low currently near Las
Vegas will continue to dig due southward this afternoon and
tonight, with northerly gradients increasing across the area.
Gusty northerly winds are expected in the usual locations, with
gusts to around 40 mph along the SBA South Coast - where a Wind
Advisory will be in effect from 2 PM to 9 PM - and through the
Interstate 5 Corridor. The north flow should limit the marine
layer cloud coverage somewhat even as heights aloft lower and a
weak eddy sets up over the San Pedro Channel. Expect we will see
some low clouds over the LA Coast, extending into the San Gabriel
Valley, and along the Central Coast.

As the low aloft pushes south of the area, SW Ca will be between
a ridge building over the northern half of the state and the low
to the southeast. Heights will rise some by Monday afternoon, with
daytime highs expected to bump up a few degrees compared to
today`s highs. This will be the start of a warming trend that will
persist through Wednesday, as the ridge expands over the southern
half of the state. In addition, gradients will begin to trend
offshore Monday night into Tuesday, setting up a weak Santa Ana
wind event. At this time winds over the mountains and valleys of
LA/VTA Counties look to remain near/ just below Advisory levels.

There will be enough offshore flow Monday night into Tuesday to
preclude any stratus formation, except for the southern portion
of the LA coast where a weak eddy will have enough of an effect to
bring clouds to the area. The eddy is forecast to strengthen some
Tuesday night into Wednesday, pushing low clouds further north
along the coastline. However, the Ventura County is unlikely to
see low clouds and fog, except possibly along the immediate
coastline.

As the ridge moves overhead on Wednesday, heights should rise
to 582 mb, with highs in the 70`s near the coast and 80`s inland.

.LONG TERM (THU-SUN)...21/132 PM.

The upper ridge over California will weaken on Thursday as it
begins to shift east of the area. This supports a cooling trend
that will likely persist through Sunday. An upper low over the
East Pacific is forecast to form a closed circulation and slowly
move toward the coast along 30 N Latitude, finally approaching the
coast either Saturday or Sunday depending on the model. The EC
and GFS agree reasonably well with this solution through Friday
afternoon, but after that time the GFS moves the low more quickly.
The GFS solution shows the low along the coast by Saturday
evening, with the EC trailing behind by at least 12 hours. Both
solutions bring some rain chances to the area, with the EC later
and slightly wetter. As with most closed low solutions in the
extended, this is a low confidence forecast so have kept pops
below slight chance, and maintained cooler temperatures.

&&

.AVIATION...21/2315Z.

At 2300Z, the marine inversion was based around 4300 feet. The
top of the inversion was 5500 feet with a temperature of
12 degrees Celsius.

Overall, low to moderate confidence in coastal/valley TAFs and
high confidence in desert TAFs. There is an equal chance of
coastal and valley sites being either clear or developing CIG
restriction late tonight and Monday morning.

KLAX...Low confidence in 00Z TAF. There is a 50% chance that CAVU
conditions will persist through TAF period. If CIG restrictions do
develop, confidence in flight category is low.

KBUR...Low confidence in 00Z TAF. There is a 50% chance that CAVU
conditions will persist through TAF period. If CIG restrictions do
develop, confidence in flight category is low.

&&

.MARINE...21/122 PM.

For the Outer Waters, good confidence that SCA winds will persist
through Monday, with sub-SCA conditions Tuesday through Thursday.

For the Inner Waters north of Point Sal, moderate confidence in
current forecast. The latest guidance suggests winds will get
strong enough for SCA conditions for a short time from late
afternoon through mid evening.

For the Inner Waters south of Point Conception, SCA conditions
are expected in the western Santa Barbara Channel from late this
afternoon through mid evening. Elsewhere, winds are expected to
remain below SCA levels. There is a 30% chance of SCA conditions
Monday evening....mainly in the western portion of the Santa
Barbara Channel. Otherwise sub- SCA conditions are expected
through the period.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 9 PM PDT this evening for zone
      39. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PDT this evening
      for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 9 PM PDT Monday for
      zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (WED-SUN).

No significant hazards expected.

&&

$$

PUBLIC...Smith
AVIATION...RAT
MARINE...Sweet
SYNOPSIS...Kj

weather.gov/losangeles



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