Gale Watch 24, NWS Los Angeles, CA

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
1126 PM PDT Tue May 25 2021

.SYNOPSIS...25/825 PM.

Afternoon temperatures will gradually cool as overnight and
morning low clouds and fog become more widely spread across the
region through the week. Gusty northwest winds will also continue
with the strongest winds focused over southern Santa Barbara
County.

&&

.SHORT TERM (TUE-FRI)...25/923 PM.

High cloudiness continues to stream over southern California this
evening as a weak upper-level trough of low pressure about 200
miles south-southwest of Point Conception continues to move east.
This trough moving mainly to the south of the area will phase with
an upper-level trough over eastern Oregon and bring a cooling
trend to the area. Onshore flow will continue to increase over
the coming days, likely peaking on Friday. A noticeably absent
stratus deck the last several nights, should take hold of the
cloud pattern late tonight or early Wednesday morning. For folks
hoping to view the lunar eclipse, the best chance of viewing it
will be over the inland areas and away from the coast. For folks
living in the coastal areas, there is a chance people living near
the coast will get to see some of it, or its entirety, depending
upon one location after the high level clouds will thin after
midnight and before the stratus moves in around daybreak. A few
minor tweak were made for the cloud forecast, with the highest
confidence for low clouds and fog for the Central Coast.

A wind advisory remains in effect for southern Santa Barbara
County tonight as gusty Sundowner winds continue. Winds gusts
between 35 and 50 mph have been observed, so far. No changes are
planned for the wind advisory headlines at this time.

***From Previous Discussion***

Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, weak trough will linger over the
area through the period with minor day-to-day changes in H5
heights. Near the surface, onshore gradients to the east are
forecast to increase through the period with continued northerly
offshore gradients in the evening.

Forecast-wise, the above pattern will lead to relatively typical
late May weather. Main issue will continue to be the winds. Models
indicate some stronger northerly gradients tonight which should
result in one more night of advisory-level Sundowner winds across
southern SBA county. For Wednesday night and Thursday night, the
Sundowner pattern will continue, but speeds should be below
advisory levels as gradients weaken. Also, will need to watch for
some increased northerly winds through the I-5 Corridor on
Thursday night/Friday as LAX-BFL increases and MOS products
indicate stronger winds at Sandberg. Otherwise, the increasing
onshore gradients will generate the typical gusty southwesterly
winds each afternoon/evening across interior sections.

As for clouds, some cirrus clouds drifting overhead will bring
partly cloudy to the area tonight. Additionally, there may be some
stratus/fog across the Central Coast as well as the LAX coastal
plain. Any fog that develops tonight will likely be dense as the
marine inversion will remain quite shallow. For the balance of the
short term period, the inland extent of stratus/fog should
increase each day with the increasing onshore gradients. The
lingering Sundowner winds will likely keep most stratus/fog at bay
for the southern SBA Coast.

As for temperatures, will expect some cooler conditions with
the weak upper trough overhead and increasing onshore flow.
Temperatures will hover around seasonal normals with minor
day-to-day fluctuations, based on the whims of the onshore flow
and marine layer.

.LONG TERM (SAT-TUE)...25/153 PM.

For the extended, models continue to exhibit good synoptic
agreement. At upper levels, trough will deepen over the area on
Saturday then develop a cutoff low near the CA/AZ on Sunday. For
Monday and Tuesday, the low will move east as a rather pronounced
ridge develops along the West Coast. Near the surface, varying
amounts of onshore flow are forecast to continue.

Forecast-wise, Saturday/Sunday look to be the coolest days as
marine layer should be rather deep and H5 heights/thicknesses
decrease. There really is no significant moisture associated with
this upper trough/low, so no appreciable rainfall threat. However
depending on the deepening marine inversion, there could be some
patchy drizzle west of the mountains, especially on Sunday. Gusty
southwesterly winds will continue during the afternoon/evening
hours across interior sections.

For Monday/Tuesday, expect the beginning of a warming trend as the
upper ridge develops off the West Coast. The rising H5 heights
should result in gradually less inland extent of any marine layer
stratus/fog while temperatures climb to above normal levels.

&&

.AVIATION...26/0623Z.

At 05Z at KLAX, the marine layer was 800 feet deep. The top of
the inversion was around 2300 feet with a temperature of 22 C.

Good confidence in inland TAFs. Low confidence in coastal TAFs
where there is a 30 percent chc of no low clouds at sits with low
clouds in the fcst and a 30 percent chc of IFR cigs at sites that
are forecast to remain clear. If cigs do come in - timing could be
off by +/- 2 hours and the VFR transition +/- 1 hour. There is a
30 percent chc that there will be IFR cigs rather than MVFR cigs.
Good confidence that low clouds will arrive fairly early in the
evening tonight but lower confidence in exact time.

KLAX...Low confidence in TAF. There is a 30 percent chc of no low
clouds. Low clouds could arrive as late as 12Z. There is a 30
percent chc that the cigs will be OVC008. Good confidence that low
clouds will arrive earlier this evening but low confidence in
exact timing. Any east wind component will be 6 kt or less.

KBUR...Good confidence in TAF.

&&

.MARINE...25/912 PM.

There will be areas of patchy fog, locally dense with visibility
one nautical mile or less, across the coastal waters during the
overnight and morning hours through the week. The fog is most
likely to develop across the waters off the Central Coast and
west of Los Angeles County tonight and will be more widely spread
as the week progresses.

Across the outer waters... Winds will be at least Small Craft
Advisory (SCA) level across all of the outer waters through
Sunday. Winds will be gale force through tonight and likely on
Friday and and Saturday as well. Seas will be SCA level on
Wednesday.

Across the inner waters north of Point Sal... Winds will be SCA
level primarily during the afternoon and evening hours through
Sunday. Otherwise, conditions will be below SCA level.

For the inner waters south of Point Conception... Winds will be SCA
level through late tonight across western portions of the Santa
Barbara Channel. Winds across all of the inner waters will likely
be SCA level Friday and Saturday primarily during the afternoon
and evening hours. Otherwise, conditions will be below SCA level.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Wednesday for zones
      39-52. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 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).
     Small Craft Advisory in effect from 3 AM Wednesday to 9 AM
      PDT Thursday for zone 670. (See LAXMWWLOX).
     Gale Watch in effect from Thursday morning through late
      Thursday night for zone 670. (See LAXMWWLOX).
     Small Craft Advisory in effect from 3 AM Wednesday to noon
      PDT Thursday for zones 673-676. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through Friday
      morning for zones 673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (FRI-TUE).

Gusty northwest to north winds will affect Santa Barbara County
and the Antelope Valley through next weekend, creating driving
hazards and elevated fire weather concerns. Steep seas and near
Gale force winds will create hazardous boating hazards into next
week.

&&

PUBLIC...Hall/Thompson
AVIATION...Rorke
MARINE...Kj
SYNOPSIS.../Kj

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