142
FXUS66 KLOX 071607
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
907 AM PDT Tue May 7 2024

.SYNOPSIS...07/441 AM.

Dry weather is expected through early next week. There will be
areas of gusty northwest to north winds through tonight. After
slight cooling today, some warming is expected Wed. Mostly benign
weather is expected Thursday through early next week, with areas
of night through morning low clouds, mainly in coastal areas.
Expect mostly minor day to day changes in maximum temperatures
Friday and Saturday, with some cooling possible Sunday and Monday.

&&

.SHORT TERM (TDY-THU)...07/907 AM.

***UPDATE***

Generally sunny skies this morning will continue this afternoon.
Northwest winds will continue through this evening, resulting in
Wind Advisory gusts over the most wind-prone areas (like the
northern mountains, Santa Ynez Range and the Antelope Valley).
Gusts are generally in the 25 to 40 mph range in those areas, but
should increase another 10 mph this afternoon and evening. The
current forecast is in good shape with no updates needed.

***From Previous Discussion***

Except for patchy low clouds and fog across the southern Central
Coast and Santa Ynez Valley, and portions of interior SLO County,
skies were clear across the region. Any low clouds should
dissipate by mid morning. Otherwise, today will be a mostly sunny
day, with just some high clouds from time to time. Broad, weakly
cyclonic northwesterly flow aloft will continue across the region
today. Heights will actually drop a bit today as a vort drops
south thru the Great Basin. The WRF shows a bit of cooling at 950
mb. Overall, changes are minimal, so do not expect too much
change in max temps from those on Mon.

Gusty north winds continued across the I-5 Corridor and the mtns
of northern VTU County, and a Wind Advisory remains in effect
thru mid morning. This looks fine, since winds will be
diminishing and should remain below advisory levels much of the
day. However, sharpening N-S gradients, increasing flow aloft,
and subsidence support another round of gusty northwest to north
winds late this afternoon/early this evening thru late tonight.
Winds should reach advisory levels late this afternoon across
southwestern SBA County, thru the I-5 Corridor, in the western
foothills of the Antelope Valley, and in far western portions of
the Antelope Valley itself. During the early evening hours.
advisory level winds should also develop in the mountains of
VTU County, the interior mountains of SBA County, southeastern
SBA County, and the Santa Clarita Valley. This is already nicely
accounted for in the current batch of wind advisories, with the
only addition being the far western portion of the Antelope Vly.

The low level flow should turn northeasterly late tonight and Wed
morning. This should bring an end to advisory level winds in most
area by late tonight. For late tonight and Wed morning, some
gusty NE winds are possible in the mtns of L.A./eastern VTU
County, and locally in the valleys, but expect the northeast
winds to remain below advisory levels. The WRF shows some stratus
moving into coastal areas of L.A. County and portions of the
southern Central Coast and Santa Ynez Valley late tonight and Wed
morning, but with weak offshore flow developing, any low clouds
should be gone quickly Wed morning. Heights across the region will
be lower on Wed, but 950 mb temps will actually rise west of the
mountain due to the weak offshore flow. Therefore, expect a few
degrees of warming in most areas on Wed, especially in the valleys
and across interior sections of the coastal plain.

A strong-"ish" vort will move south southwestward thru the Great
Basin Wed night and Thu, causing a weak closed upper low to
develop over southern Nevada and southwestern Utah, with a trough
extending southwestward into the forecast area. There is still
some uncertainty as to how much stratus will develop Wed night and
Thu morning, but at this point, it does look as though there will
be more extensive low cloud coverage, affecting coastal areas of
L.A./VTU Counties, the Central Coast and Santa Ynez, and possibly
the lower valleys of L.A./VTU Counties. With lowering heights,
cooling at 850 and 950 mb, and increasing onshore flow, expect a
few degrees of cooling in most areas Thu.

.LONG TERM (FRI-MON)...07/506 AM.

What happens with the upper low over Nevada will have implications
on the resultant weather across the forecast area Fri thru Mon.
The operational runs of the GFS and EC are in moderately good
(but not great) agreement, showing the upper low drifting westward
into southeastern CA Fri.

The GFS shows the upper low farther south and west than does the
EC, which would bring some cooling to most of the region Fri. The
EC actually shows slight warming Fri, since it indicates low
level flow turning weakly offshore. The upper low will move little
Fri night, then should move to the east on Sat, with a weak ridge
building into the region during the day. Expect mostly minor
changes in max temps on Sat.

The stratus pattern is very uncertain. With a broad trough
extending into the region, would typically expect some night thru
morning low clouds Thu night and Fri night, especially since we
are heading into mid May, so areas of low clouds in coastal/lower
valley areas looks reasonable. However confidence in the low cloud
forecast is rather low.

Overall, a generally benign pattern looks to be setting up for Sun
and Mon. The weak ridge which will move into the area late Sat
will flatten out. Heights will lower a bit and onshore flow will
increase, so there should be some cooling in most area Sun and Mon.

&&

.AVIATION...07/1118Z.

At 1030Z, there was no marine layer or inversion at KLAX.

Overall, moderate to high confidence in 12Z TAF package. Thru the
period, high confidence in most sites being CAVU. The only
exceptions will be KPRB (with a 40% chance of IFR conditions
12Z-16Z) and KLAX/KLGB/KSMO (with a 50% chance of CIG/VSBY
restrictions after 09Z).

With gusty winds this afternoon, there is a 50% chance of MVFR
VSBYs in blowing dust for KPMD/KWJF 20Z-04Z.

KLAX...Overall, moderate confidence in 12Z TAF. High confidence in
CAVU conditions thru this evening. For tonight/Wednesday morning,
there is a 50% chance that CIG/VSBY restrictions will not develop
10Z-17Z. No significant easterly wind component is expected.

KBUR...High confidence in 12Z TAF.

&&

.MARINE...07/837 AM.

For the Outer Waters, high confidence in current forecast. Today
through tonight, Gale force winds are expected and GALE WARNINGS
are in effect. For Wednesday and Wednesday night, a combination
of Small Craft Advisory (SCA) level winds and seas are expected.
For Thursday through Saturday, winds and seas will remain below
SCA levels.

For the Inner Waters north of Point Sal, moderate to high
confidence in current forecast. SCA level winds are likely this
afternoon and evening. For Wednesday, there is a 30% chance of SCA
level winds in the afternoon/evening hours. For Thursday through
Saturday, high confidence in winds and seas remaining below SCA
levels.

For the Inner Waters south of Point Conception, high confidence in
current forecast. Across the western half of the Santa Barbara
Channel, SCA level winds are expected this afternoon and tonight.
Otherwise across the southern Inner Waters, winds and seas will
remain below SCA levels through Saturday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory remains in effect from 7 PM this evening to 3
      AM PDT Wednesday for zones 88-350-352-353-376-377. (See LAXNPWLOX).
     Wind Advisory remains in effect from 4 PM this afternoon to 3
      AM PDT Wednesday for zones 349-351-378-381. (See LAXNPWLOX).
     Wind Advisory in effect from 4 PM this afternoon to 3 AM PDT
      Wednesday for zone 383. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 3 PM this afternoon to 9
      PM PDT this evening for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 PM this afternoon to 3
      AM PDT Wednesday for zone 650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Wednesday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...DB/Kittell
AVIATION...RAT
MARINE...RAT/Schoenfeld
SYNOPSIS...DB

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox