Weather Service Report


030 
FXUS66 KLOX 230308
AFDLOX

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOS ANGELES/OXNARD CA 
808 PM PDT Sat Apr 22 2017

.SYNOPSIS...
A low will move in early next week for a drop in temperatures... 
breezy mountain winds and overnight coastal fog. We will be 
between a high to the west...an a low to our east around midweek 
for fair skies and gusty winds with temperatures to remain above 
normal into the weekend.

&&

.SHORT TERM...(Tonight-TUE)

Another very warm day across inland sections of Southwest
California, with many locations climbing into the 90s this 
afternoon. Closer to the coast, there was some cooling due to an 
earlier and more pronounced sea breeze. At upper levels, a weak
upper trough moving through Northern and Central California
tonight will bring weak onshore flow near the surface. A wind
advisory is in effect for the Santa Barbara county mountains 
and south coast. Wind gusts between 35 and 45 mph will be
common in the advisory area, especially from Gaviota to Goleta.
As of 8 pm, the peak wind gust recorded has been Refugio Hills
at 47 mph. A tightening northwest pressure gradient generating
these gusty winds, however upper level wind support fairly minimal
tonight. As of 8 pm, the Santa Barbara-Santa Maria pressure
gradient at -4.5 mb.

The return of weak onshore flow and a developing eddy circulation
over the coastal waters is expected to bring a return of low 
clouds and fog to portions of the coast later tonight into Sunday 
morning. At the moment, a surge of higher level clouds moving over
the forecast area, which may delay the onset of the lower level 
cloud/fog development, but high clouds are expected to thin out 
overnight. Initially, marine inversion is expected to be very 
shallow which will likely cause patchy dense fog. However, marine 
layer expected to deepen fairly rapidly by Sunday morning which 
should allow for improvement in visibilities. The increased 
onshore flow and marine layer influence will bring widespread 
cooling across the region on Sunday, with temperatures returning 
closer to seasonal normals.

Gusty onshore winds will be more widespread by Sunday afternoon, 
with winds approaching advisory levels for the Central Coast and 
Antelope Valley. By Sunday night, the northwest to north flow will
increase across the district with tightening northwest pressure 
gradients and increasing upper level wind support. In fact, the 
projected Santa Barbara-Santa Maria pressure gradient for Sunday 
evening is expected to exceed -5 mb. As a result, wind advisories 
will be likely for the SBA county mountains and south coast as 
well as the I-5 corridor of the LA/Ventura county mountains. These
areas could see wind gusts in the 45 to 55 mph range.

The northwest flow pattern will continue Monday into Tuesday. With
increasing upper level wind support and continued tight north-
south pressure gradients, looking for more widespread gusty winds
with numerous wind advisories likely needed during period. There 
is the potential that winds could approach damaging warning levels
across the mountains by Monday night or Tuesday. An eddy 
circulation will continue to bring the threat of night and morning
low clouds and fog for the LA Basin.

.LONG TERM...(WED-SAT)

Upper level trough will dive southward through the Great Basin
Wednesday through Friday, likely maintaining an extended period 
of northwest flow across Southwest California. There will likely
be periods of wind advisories during this time frame, especially
across southern Santa Barbara county, the Central Coast, and the
mountains (which could see localized high wind warning gusts). 
The northerly flow will bring some downslope warming to
coastal/valley areas during this period, with some areas climbing
into the 80s. By Saturday, long range computer models are showing
the potential for low level offshore flow which would bring
additional warming and drying to the region.

&&

.AVIATION...22/2350Z.

At 2330Z, the marine layer was around 500 feet deep at KLAX. The 
top of the inversion was around 1500 feet with a temperature of 
25 degrees Celsius.

VFR conditions are expected through at least 05z, then there is 
an increasing chance of VLIFR to LIFR conditions at KLAX, KLGB,
KSBP, AND KSMX between 06z-13z. With an eddy circulation
developing, there is also a 20 percent chance of VLIFR/LIFR cigs
reaching KCMA and KOXR. Eddy circulation expected to deepen marine
layer over LA Basin on Sunday morning, with improving
visibilities. LLWS concerns at KSBA tonight.

KLAX...VFR Conditions are expected through at least 08z, then 
increasing chance of VLIFR to LIFR conditions between 08z-13z.
IFR conditions should redevelop on Sunday morning as eddy
circulation is expected to deepen marine layer.

KBUR...VFR Conditions are expected throughout the period. There is
a 10 percent chance of brief LIFR/IFR cigs on Sunday morning.

&&

.MARINE...23/800 PM.
Moderate to high confidence in forecast of SCA NW winds through
around midnight over the outer waters...increasing to Gale Force 
between midnight and 3 AM Sunday. The Gale Warning is in effect 
through late Monday night...but fairly high confidence that Gales
will continue through much of this coming week over the outer 
waters. Periods of gale force wind gusts could also develop at 
times across the Inner Waters...most likely during the evening 
hours for the waters north of Point Sal...and Tuesday night 
through Thursday for the waters south of Point Conception.

A shallow marine inversion could bring patchy dense fog with 
visibility one nautical mile or less tonight through Sunday 
morning across the Coastal Waters, and possibly again Sunday
night through Monday morning.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Beach Hazards Statement in effect from 8 AM PDT Sunday
      through Monday evening for zones 34-35-40-41-87. (See LAXCFWLOX).
     Wind Advisory in effect until 6 AM PDT Sunday for zones
      39-52. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Monday for
      zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Sunday for
      zones 670-673-676. (See LAXMWWLOX).
     Gale Warning in effect from 3 AM Sunday to 3 AM PDT Tuesday
      for zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK...(TUE-SAT)
Very gusty north to northwest winds are expected across southern 
Santa Barbara County, the Central Coast, the I-5 corridor, and 
the Antelope Valley. Advisory level winds expected at times and
possibly exceeding warning levels, especially in the I-5 corridor
and southern SB County Wednesday and Thursday.

&&

$$

PUBLIC...Gomberg
AVIATION...Gomberg
MARINE...Smith
SYNOPSIS...STu

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