Area Forecast Discussion
Issued by NWS Los Angeles, CA

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318
FXUS66 KLOX 231625
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
925 AM PDT Thu May 23 2019

.SYNOPSIS...23/319 AM.

A broad trough of low pressure over the state will continue a
cooler and unsettled weather pattern through Memorial Day. A
series of weak weather system will move over the region through
Saturday, then a stronger storm system will affect the region for
the holiday weekend. A warming and drying trend is possible for
mid-to-late next week.

&&

.SHORT TERM (TDY-SAT)...23/924 AM.

Clouds have filled in once again as the low level flow has
shifted from northerly to southwesterly. This is creating some
drizzle/light rain along the Central Coast and in the LA Valleys,
especially near the foothills. The low level moist layer is so
deep that a few showers have even been reported in the Antelope
Valley. It will likely remain mostly cloudy much of the day as
gradients continue to trend onshore. May see some clearing over
the AV and interior SLO but otherwise lots of clouds, a few
showers, especially in the mountains, and temps well below
normal.

***From previous discussion***

Weak ridging aloft should briefly build in over the region between
Friday afternoon and Saturday morning as the weak disturbance
clear outs and another trough digs south out of Canada. Slight
warming with less cloudiness should be expected for Friday night
and early Saturday, then cloudiness should increase into Saturday
night with rain chances developing late.

.LONG TERM (SUN-WED)...23/353 AM.

The trough will continue to dig into the region through the
weekend. Originating from the Gulf of Alaska, this trough will be
an unseasonably cold trough for this time of year. Thunderstorms
cannot be ruled out with this trough as the 500 mb cold pocket
approaches temperatures near -25 degrees Celsius, similar to
yesterday`s trough, but the movement and overall pattern could set
up differently. Gusty winds will likely develop with the trough
as it moves into the region. The surface pressure gradient
tightens and wind advisory level winds could develop across the
interior portions of the area and across the coastal sections.
Snow levels could dip to between 5000 and 6000 feet with this
system as 700 mb temperatures are cold enough to bring snow to the
higher elevations of the area.

Gusty northerly winds seem a bit more certain behind the exiting
storm system Monday night through Wednesday, especially through
Interstate 5 Corridor and across southern Santa Barbara County.
Model solutions have been consistent in suggesting this
possibility.

Confidence continues to grow for a warming and drying trend
between Tuesday and Wednesday. At least, weak ridging will nose
into the state during this period. GEFS solutions hang onto a
ridge between Tuesday and Wednesday with a relatively high measure
of predictability and probability, but confidence wanes for the
latter half of next week.

&&

.AVIATION...23/1038Z.

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

Overall, low confidence in 12Z TAF package except high confidence
in desert TAFs. For coastal and valley sites, BKN-OVC conditions
are anticipated through the TAF period with flight categories
ranging between MVFR and VFR. Timing of flight category changes is
low through the TAF period.

KLAX...Low confidence in 12Z TAF. There is a 50% chance that MVFR
CIGs will not dissipate this afternoon. East to southeast winds
near 8 knots expected 12Z-20Z.

KBUR...Low confidence in 12Z TAF. There is a 50% chance that MVFR
CIGs will dissipate this afternoon.

&&

.MARINE...23/128 AM.

For the Outer Waters, relatively high confidence in current
forecast. Small Craft Advisory (SCA) level winds and seas will
continue through this morning, before slowly diminishing this
afternoon. For tonight through Sunday morning, winds and seas will
remain below SCA level. From Sunday afternoon through Monday,
there is a 50-60% chance of SCA level winds.

For the Inner Waters north of Pt Sal, high confidence in current
forecast. Current SCA level seas will continue to slowly diminish
below advisory thresholds through today. For tonight through
Sunday, winds and seas are expected to remain below SCA levels. On
Monday, there is a 50% chance of SCA level winds in the afternoon
and evening hours.

For the Inner Waters south of Pt Conception, high confidence in
current forecast. Today through Sunday, winds and seas will remain
below SCA levels. On Monday, there is a 40% chance of SCA level
winds across the western half of the Santa Barbara Channel.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory for hazardous seas in effect until 9 PM
      PDT this evening for zones 645-670. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 PM PDT this afternoon
      for zones 673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SAT-WED).

Another storm system could bring rain, mountain snow and gusty
winds to the region late Saturday through Memorial Day. Gusty
northerly winds could linger into Tuesday through the Interstate
5 Corridor and across southern Santa Barbara County.

&&

$$

PUBLIC...MW/Hall
AVIATION...RAT
MARINE...RAT
SYNOPSIS...Hall

weather.gov/losangeles



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