Area Forecast Discussion
Issued by NWS Los Angeles, CA

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187
FXUS66 KLOX 251636
AFDLOX

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA
936 AM PDT Sun Jun 25 2017

...Updated Fire Weather Discussion...

.SYNOPSIS...
High temperatures continue away from the coast today. Offshore
trends and a weakened marine layer will warm the coastal valleys
as well. A trough of low pressure off the California Coast will
weaken high pressure aloft beginning Monday afternoon and bring a
cooling trend as onshore flow strengthens.

&&

.SHORT TERM...(TDY-TUE)

High level moisture and instability have left the area and
northwest flow has disrupted the marine lyr south of Pt
Conception. Those factors will help push temps up today several
degrees in most areas, especially those that had more extensive
clouds yesterday. Today should be the last day of any heat
advisories and warnings. There will also be some gusty northwest
winds at times through the Santa Ynez range, particularly later
this afternoon and evening. Gradients are pretty impressive but
there`s very little support aloft so winds will be pretty
localized and generally below advisory levels except for some
isolated spots in the foothills.

***From previous discussion***

The ridge will be knocked down by a pac NW trof on Monday and hgts
will drop to about 590 DM which is still very warm but still
noticeably cooler than today`s 594 DM hgts. There will not be
much change in max temps across the coasts but the vlys will see 2
to 4 degrees of cooling and the interior will see a very welcome
4 to 8 degrees knocked of the max temps.

There does not look like there will be much change in the stratus
Monday night as the pressure grads will be unimpressive and there
will not be an eddy. So it looks like most areas except the LA
coast and Central Coast will be cloud free Monday night.

The ridge will continue to be smooshed down to the south. There
will also be an increase in the onshore flow both to the north and
the east. Look for cooling across the entire area. There deserts
will further cool and will only be about 4 degrees above normal
(down from 14 degrees above today)

.LONG TERM...(WED-SAT)

The long term looks like a pretty typical June scenario. Weak
broad scale troffing will cover the west Wed and Thu. At the sfc
the onshore flow will slowly increase each day. Both of these will
combine and allow for an increase in coverage of the night through
morning low clouds. Hgts will lower a bit more on Wednesday as
well and then hold steady on Thu. Look for max temps to come in
right at normals on Wed and remain about the same on Thu.

A subtle reversal occurs Friday with a slight increase in hgts and
a small decrease in the onshore flow. There will be little or no
change to the marine layer stratus pattern but max temps will
bounce up a few degrees.

&&

.AVIATION...25/12z.

At 09z at KLAX... the inversion was around 700 feet. The top of
the inversion was around 3050 feet with a temperature of about 31
degrees Celsius.

Overall... Low confidence in the current coastal TAFs and
moderate to high confidence in the remaining TAFs. VLIFR/LIFR
conditions are along the coast but just off terminal sites at many
locations. It is difficult to judge which locations may have CIGs
and possibly VSBY take a nose dive at sunrise. Chances are
greatest for at least IFR/MVFR conditions to come in at Central
Coast and Ventura County sites and at worst MVFR conditions at
KSBA and Los Angeles County sites. Any reduced conditions should
be VFR by 18z. Otherwise and elsewhere conditions will be VFR
through the forecast period.

KLAX... Low confidence in the current TAF. IFR/MVFR conditions
may move over the airfield near daybreak and there is a ten
percent chance that LIFR conditions could develop suddenly that
time. However there is a sixty five percent chance of remaining
VFR. VFR conditions will prevail by 18z and continue through the
forecast period. There is a thirty five percent chance of
IFR/MVFR conditions after 26/10z. No east winds stronger than
seven knots are expected during the forecast period.

KBUR... Moderate to high confidence in the current TAF. There is
a less than ten percent chance of MVFR conditions around daybreak.
Otherwise VFR conditions will prevail through the forecast
period.

&&

.MARINE...25/900 AM.

For the Outer Waters... Small Craft Advisory (SCA) level
conditions will continue through at least Tuesday evening. Wind
speeds may weaken to below SCA levels during the morning hours but
will strengthen again in the afternoon.

For the Inner Waters... SCA level winds will develop in the afternoon
and evening hours through Tuesday evening across the northern
nearshore waters as well as in the East Santa Barbara Channel.
Local gusts up to 25 kt could also develop during this time from
Point Mugu to San Mateo Point west of Santa Catalina Island.

In addition to the elevated winds, a short period west to
northwest swell could impact the coastal waters Monday through
Wednesday.

&&

.FIRE WEATHER...25/1000 AM.

Hot and dry conditions with gusty winds will continue through
Monday. Although a cooling trend will begin Monday...very dry
conditions are likely to persist into Tuesday. The hot and
unstable conditions will bring the potential for plume dominated
fires which can create their own intense winds. Gusty west to
northwest winds will impact interior portions of the forecast area
through Tuesday. For Los Angeles County, the strongest winds will
be in the I-5 corridor in the mountains as well as the Antelope
Valley foothills with gusts between 30 to 40 mph. Humidities in
the single digits to teens are expected across the mountains,
deserts, and interior valleys.

For Santa Barbara County, Sundowner winds will affect the western
portions of the Santa Ynez range and South Coast (mainly from
Gaviota to Goleta), with gusts of 30 to 40 mph each evening
through Tuesday. In addition, localized humidities falling to
between 15 and 25 percent can be expected in the Santa Ynez
mountains and adjacent canyons where the downslope Sundowner winds
develop.

The combination of hot and dry conditions with locally gusty winds
will bring elevated fire weather concerns to interior sections
through Tuesday, with brief critical conditions likely each
afternoon and evening in wind-prone areas...especially Monday
afternoon and evening. If fire ignition occurs, dangerous fire
behavior should be expected. As such, the public should be extreme
careful when handling potential ignition sources such as
cigarettes, campfires, hand torches and metallic weed trimmers.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 9 PM PDT this evening for zones
      38-52>54-88. (See LAXNPWLOX).
     Excessive Heat Warning in effect until 9 PM PDT this evening
      for zone 59. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Wednesday for
      zones 645-650-670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(TUE-SAT)
No significant hazards expected.

&&

$$

PUBLIC...MW/Rorke
AVIATION...Kj
MARINE...Sweet
FIRE...Gomberg/Smith
SYNOPSIS...jld

weather.gov/losangeles



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