Gale Watch 23, NWS Los Angeles, CA

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
914 PM PDT Sun May 23 2021

.SYNOPSIS...23/856 PM.

There will be significant warming Monday and Tuesday, 5 to 10
degrees above normal, with minimal low clouds and fog just at the
coast. Modest cooling to near normal on Wednesday, with little
change through the week. Gusty northwest winds will continue
through the week, focused over Santa Barbara County.

&&

.SHORT TERM (SUN-WED)...23/856 PM.

***UPDATE***

The forecast is in good standing this evening, with only minor
tweaks made to the winds and low clouds. The current Wind
Advisories for Santa Barbara County look good, focusing over and
around the Santa Ynez Range. Low clouds and fog are expanding off
and into the Central Coast. The offshore winds that are expected
later tonight should push some of those clouds offshore, but
expecting any clouds around Santa Maria to be stubborn and might
even produce dense fog. Down south, the current SBA-SAN pressure
gradient suggests that a coastal eddy will form. With the
inversion strengthening some overnight with high pressure aloft,
and some wisps of stratus already forming near Catalina, there is
a chance that low clouds and fog will form near or over coastal
Los Angeles County. There is also chance that the marine layer
will be shallow enough to produce some dense fog.

***From Previous Discussion***

Overall, 12Z models in good synoptic agreement through the short
term period. At upper levels, low over the Great Basin will
continue to move eastward with a ridge building overhead on
Monday. However for Tuesday and Wednesday, this ridge will be
replaced by a weak trough. Near the surface, north to northeast
flow can be expected through Monday with a return of onshore flow
Tuesday/Wednesday (although some northerly gradients will remain).

Forecast-wise, main issue in the short term will continue to be
the winds. Models continue to indicate moderate northerly
gradients this afternoon through Wednesday. So, gusty Sundowner
winds will continue through/below the Santa Ynez Range tonight
through Wednesday. Will keep WIND ADVISORY in effect for zones
39/52 through tonight with a high likelihood that advisories will
be needed again Monday night and Tuesday night. Peak wind gusts of
35-50 MPH can be expected with the strongest winds from Refugio
westward. The northerly gradients will also generate some gusty
north winds through the I-5 Corridor, but widespread advisory
level winds are not anticipated in this area. Otherwise, models do
indicate some weak northeasterly offshore winds tonight/Monday
morning across Ventura/LA counties. However, given the weakness of
the gradients and upper level support, northeasterly winds will
remain below advisory levels.

As for clouds, the north to northeast flow should keep most of the
area stratus-free tonight/Monday morning (although some patchy
stratus/fog would not be out of the question around the Santa
Maria area as well as Long Beach). From Monday afternoon through
Wednesday, gradual increase in onshore flow should allow for
stratus to become more established across the coastal plain and
coastal valleys although northerly flow will keep stratus/fog
very limited across southern SBA county and Ventura county. Other
than any possible stratus, skies should remain mostly clear
through the period.

As for temperatures, the combination of the upper level ridge and
weak offshore gradients will allow for a noticeable warming trend
on Monday. In fact, many coastal/valley areas will be in the upper
70s and 80s with even some localized 90+ readings. For Tuesday and
Wednesday, expect a cooling trend for all areas with gradually
increasing onshore flow and weak trough developing aloft.

.LONG TERM (THU-SUN)...23/156 PM.

For the extended, 12Z models do not indicate anything too
problematic at this time. For Thursday through the weekend, models
indicate increasing onshore gradients. So, the marine layer
status and fog should gradually become more extensive across the
coasts and coastal valleys. With this increasing onshore flow and
marine influence, temperatures will be cooler for most areas,
generally at or a couple degrees below seasonal normals,
especially by Saturday/Sunday. As for winds, the increasing
onshore gradients will result in some gusty southwesterly winds
during the afternoon/evening hours across interior sections. It
looks like the northerly gradients relax during the extended
period, so Sundowners should be less of an issue.

&&

.AVIATION...23/1952Z.

At 1730z at KLAX... the inversion was around 1350 feet. The top of
the inversion was around 2250 feet with a temperature of about 15
degrees Celsius.

Overall... Moderate to high confidence in the current TAFs.
IFR/MVFR CIGs will develop at KSBP and KSMX about 05z. There is a
twenty five percent chance of IFR/MVFR CIGs at KPRB after 12z and
a ten percent chance of MVFR CIGs at KLAX/KSMO/KLGB during the
08z-16z period. Otherwise and elsewhere, VFR conditions will
prevail.

KLAX... Moderate to high confidence in the current TAF. There is
a ten percent chance of MVFR CIGs developing during the 08z-16z
period. Otherwise, VFR conditions will prevail. East winds greater
than 8 kts will not develop during the forecast period.

KBUR... High confidence in the current TAF. VFR conditions will
prevail throughout the forecast period.

&&

.MARINE...23/912 PM.

Across the outer waters... Winds will likely be at least Small
Craft Advisory (SCA) level through Friday with the strongest winds
in the afternoon and evening hours. There is a sixty percent
chance of gale force winds from near Point Conception and
northward Monday afternoon through Tuesday. Seas will be SCA
level on Tuesday. Otherwise, conditions will be below SCA level.

Across the inner waters north of Point Sal... SCA level winds
will develop Monday afternoon and likely continue during the
afternoon and evening hours through Friday. Otherwise, conditions
will be below SCA level.

For the inner waters south of Point Conception... Winds will
likely be SCA level across the Santa Barbara Channel and south to
Point Mugu through Friday. Winds will be strongest during
afternoon and evening hours. Otherwise and elsewhere, conditions
will be below SCA level.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Wind Advisory in effect until 3 AM PDT Monday for zones
      39-52. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect from 2 PM to 9 PM PDT Monday
      for zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 6 PM PDT Monday for
      zones 670-673. (See LAXMWWLOX).
     Gale Watch in effect from Monday evening through Tuesday
      morning for zones 670-673. (See LAXMWWLOX).
     Small Craft Advisory in effect until 6 AM PDT Tuesday for
      zone 676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (WED-SUN).

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...Thompson/Kittell
AVIATION...Kj
MARINE...Kj
SYNOPSIS...RK

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