217 
FXUS66 KLOX 120938
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA 
238 AM PDT Sat Oct 12 2019

.SYNOPSIS...12/237 AM.

Persisting dry, breezy conditions will keep the high fire danger 
over much of Ventura and Los Angeles Counties through today. 
Afternoon temperatures will remain above normal today, but should 
begin cooling off Sunday. Despite the warm daytime temperatures, 
the Antelope Valley will see low temperatures in the mid 20s to
mid 30s early this morning.

&&

.SHORT TERM (TDY-MON)...12/150 AM.

Skies were clear in all areas early this morning thanks to a 
continuation of the dry offshore flow. LAX-DAG gradients were -2.9
mb at 08Z which was up 4 mb in the last 24 hours. Weakening 
gradients and diminished upper level support have lead to much 
weaker winds, with some gusts around 30 mph lingering in the mtns 
and foothills of VTU/L.A. Counties. Otherwise winds in the favored
areas were in the 10 to 20 mph range for the most part which will
continue into this morning. In addition, light winds and the very
dry air mass will allow temps in the Antelope Valley to fall into
the mid to upper 20s toward daybreak, especially in the northern 
parts of the Valley. As a result, the Freeze Warning remains in 
effect for this area until 8 AM PDT. Please see the latest Non-
precipitation Weather Message (LAXNPWLOX) for further details.

Generally weak upper level troffiness will persist over swrn CA thru 
tonight, then a sharper upper level trof will approach on Sun before 
pushing thru the area Sun night and early Mon. H5 heights will lower 
to about 569-571 DM with the upper level trof, then recover 
slightly to 576-577 DM Mon afternoon. The upper level trofs will 
increase onshore flow thru the weekend, with a slight weakening of
the onshore flow expected on Mon.

Sunny skies will cover the forecast area today. The marine 
inversion is expected to gradually become re-established late 
tonight into Mon morning with low clouds and fog expected to 
affect the L.A. County coast and Santa Catalina Island. Increased 
onshore flow and the development of an eddy over the SoCal Bight 
will help to deepen the marine inversion Sun night. As a result, 
much more coverage of marine layer clouds and fog can be expected 
from the coast to the valleys Sun night and Mon morning. 
Otherwise, mostly clear skies will prevail across the forecast 
area tonight thru Mon.

Temps are forecast to be about 4 to 8 deg above normal for the 
coast, vlys and mtns today, and a couple of degrees below normal for 
the Antelope Vly. A cooling trend back to near normal to several 
degrees below normal will then take place Sun thru Mon. Highs in 
the warmest vlys and inland coastal areas should reach the mid to 
upper 80s today, then cool to the mid 70s to around 80 on Sun, and 
to the 70s on Mon.

.LONG TERM (TUE-FRI)...12/153 AM.

Some upper level troffiness is expected to linger into Tue over 
the region, then flat upper ridging with H5 heights around 581-583
DM should move in for Wed. An upper level trof should move thru 
srn CA on Thu followed by flat upper level ridging for Fri, with a
dry westerly flow aloft.

Low clouds and fog should affect most coastal areas Mon night into 
Tue morning, then just a few coastal areas night and morning hours 
Tue night into Thu morning. Increased onshore flow should bring a
deeper marine inversion and more widespread low clouds along the 
coast into some adjacent vlys Thu night into Fri morning. 
Otherwise, mostly clear skies will continue across southwestern CA
Tue thru Fri.

Weak offshore gradient trends Tue morning and Wed morning will help 
daytime temps to increase to near normal to several degrees above 
normal thru Wed, followed by increasing onshore gradient trends and 
cooler temps Thu and Fri. Highs in the warmest vlys and inland 
coastal areas should reach the upper 70s to mid 80s Tue, 80s on Wed, 
upper 70s to lower 80s Thu, and mid 70s to around 80 on Fri.

&&

.AVIATION...12/0540Z.

At 0530Z...there was a surface-based inversion at KLAX. The top 
of the inversion was at 1100 ft with a temperature of 25 deg C.

High confidence in VFR at all airfields through the period, 
except for MVFR FU at times near any fires, especially KBUR and 
KVNY.

KLAX...High confidence in VFR through Sat evening, then there is a
50%-60% chance of IFR cigs developing by 10Z late Sat night. 

KBUR...High confidence in VFR through Sat evening. Periodic MVFR 
vsby due to smoke will be possible through the period.

&&

.MARINE...11/808 PM.

Northeast wind gusts will diminish and shift to the east and
southeast overnight. The area nearshore between Ventura Harbor and
Malibu could see local gusts to 20 knots, otherwise easterly winds
should stay below 15 knots. After Saturday morning, high confidence
in winds and seas staying below SCA everywhere through Sunday. NW
winds with gusts around 20 kt possible Monday and Tuesday for the
waters off the Central Coast with SCA winds possible Wednesday
across the outer waters and portions of the waters nearshore.

&&

.FIRE WEATHER...12/157 AM.

Through this morning, northeast winds are expected to gust 
between 15 and 25 mph with local gusts to 30 mph across the wind 
prone mountains and valleys of Los Angeles and Ventura counties, 
then switch to onshore and remain breezy this afternoon. With the
continuation of widespread single digit humidities, warm 
temperatures, and breezy conditions, the Red Flag Warning remains 
in effect for the Los Angeles and Ventura county mountains, Santa 
Clarita Valley, Ventura county valleys, and San Fernando Valley 
through 6 PM this evening.

Warm temperatures are on track for today, with highs in the 80s 
to near 90 degrees across many coastal and valley areas. Much of 
San Luis Obispo and Santa Barbara counties will continue to see 
elevated to brief critical fire weather conditions due to locally 
breezy offshore conditions and widespread single digit humidities.
Rapid fire spread and extreme fire behavior are still possible 
with any existing fires and new ignitions.

This is a dangerous situation, with critical fire weather and 
fuel conditions. If a new fire were to start, the environment will
still be favorable for very rapid fire spread, long range 
spotting, and extreme behavior. The public should be urged to use 
extreme caution with any potential fire ignition sources. Past 
fires have begun from things like discarded cigarettes, metallic 
hedge trimmers, welding activities, and campfires.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Freeze Warning in effect until 8 AM PDT this morning for zone
      59. (See LAXNPWLOX).
     Red Flag Warning in effect until 6 PM PDT this evening for
      zones 244>246-253-254-288-547. (See LAXRFWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (MON-FRI).

No significant hazards expected.

&&

$$

PUBLIC...Sirard
AVIATION...Sirard
MARINE...Smith
FIRE...Gomberg/Sirard
SYNOPSIS...Phillips/Sirard

weather.gov/losangeles