Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/27/19

Area Forecast Discussion...UPDATED

National Weather Service Los Angeles/Oxnard CA

 811 PM PDT Wed Jun 26 2019

.SYNOPSIS...26/612 PM.

Overnight and morning low clouds will continue along much of the
coast and adjacent valleys through the week. Breezy afternoon and
evening winds will develop each day in the mountains and deserts
through Thursday. Temperatures will remain relatively cool through
Friday then warm a bit this weekend.

&&

.SHORT TERM (TNT-SAT)...26/810 PM.

The latest surface observations indicate onshore flow weakening
some this evening as high pressure aloft to the east strengthens
and expands westward. 500 mb heights climb each day over the
region into the weekend. Onshore flow should continue to weaken
for late this week as subsiding air aloft presses down on top of
the marine layer and thins it. The latest AMDAR soundings from
KLAX indicate a marine layer depth currently near 2100 feet deep.
If NAM BUFR time height sections play out as suggested, the marine
layer depth should thin to between 1200 and 1800 feet deep by
Thursday morning, then to around 1000 feet by Friday morning. With
onshore flow continuing to weaken each day and the marine layer
depth thinning, a warming trend will develop, especially away
from the coast.

***From Previous Discussion***

Overall, 12Z models in good synoptic agreement through the
short term period. At upper levels, low slowly moves across the
Pacific Northwest through Saturday while high pressure builds
over the desert Southwest. Near the surface, onshore east-west
gradients gradually diminish with weak offshore north-south
gradients.

Forecast-wise, main challenge will continue to be the marine layer
stratus and temperatures. With the above synoptic pattern, H5
heights increase slightly through Saturday which will help make
the marine inversion more shallow. The weakening onshore gradients
and weak northerly offshore gradients will also help make the
inversion more shallow and result in gradually less extensive
stratus/fog each night and morning through Saturday. Additionally,
stratus dissipation will be better each afternoon. Other than
night and morning stratus, skies should remain mostly clear
through Saturday.

With the rising H5 heights and lessening marine influence, there
will be a warming trend for all areas with high temperatures
around seasonal normals for most areas Friday and Saturday.

As for winds, the weakening onshore flow to the east will result
in decreasing southwesterly winds across the mountains and deserts
each afternoon and evening. There will likely be some local gusts
near advisory-levels in the foothills of the Antelope Valley. Also
will have to watch the northerly offshore flow. Given the forecast
gradients (SBA-SMX and SBA-BFL), there could potentially be some
low end advisory-level Sundowner winds across the western half the
SBA South Coast each evening tonight through Friday night. Do not
anticipate any northerly winds to be widespread enough for an
advisory, but this will need to be monitored closely.

.LONG TERM (SUN-WED)...26/159 PM.

For the extended, 12Z models continue to exhibit good synoptic
agreement through the long-term period. At upper levels, a broad
scale trough will develop over the West Coast. Near the surface,
weak gradient pattern will continue.

Forecast-wise, the extended period looks to be rather
unremarkable. With the weak northerly offshore gradients and weak
onshore gradients to the east, the marine layer stratus will
remain rather limited Sunday through Tuesday, generally across
the coastal plain south of Point Conception. However by Wednesday,
the marine layer stratus could be more extensive, developing over
the Central Coast and into the coastal valleys. Otherwise, skies
should remain mostly clear through Wednesday. The northerly
gradients will continue to generate locally gusty northerly winds
each evening, especially through the Santa Ynez Range.
Temperatures will cool a couple of degrees on Sunday then remain
relatively persistent Monday/Tuesday before cooling slightly more
on Wednesday.

&&

.AVIATION...27/0237Z.

At 0130Z, the marine layer depth was around 2100 feet deep at
KLAX. The top of the marine inversion around 2600 feet with a
temperature around 18 degrees Celsius. There was another inversion
above up to around 5200 feet.

Low-to-moderate confidence in the current forecast. Higher
confidence in timing, less confidence in flight categories.

IFR to MVFR conditions will likely spread into coastal and valley
terminals through 13Z. There is a chance that conditions could be
one category lower, especially north of Point Conception. Better
clearing is expected for the valley terminals on Thursday. Coastal
terminals could clear up to 1 hour earlier/later than forecast.

KLAX...MVFR to VFR conditions will become predominantly MVFR
between 04Z and 07Z. There is a 30 percent chance of IFR
conditions between 04Z and 08Z. VFR conditions could develop as
soon as 19Z or as late as 21Z.

KBUR...MVFR conditions will spread into KBUR between 07Z and 10Z.
There is a 50 percent chance of IFR conditions. VFR conditions
could develop as soon as 1730Z or as late as 1930Z.

&&

.MARINE...26/744 PM.

For the Outer Waters, a Small Craft Advisory (SCA) remains in
effect through at least late Thursday night. There is a 60
percent chance that the SCA will have to be extended through at
least Saturday. There is a 30 percent chance of gales between
Thursday afternoon and Friday night.

For the Inner Waters north of Point Sal, SCA winds will persist
through late tonight. There is a 60 percent chance of SCA level
winds each afternoon and evening through Saturday.

For the Inner Waters south of Point Conception, winds and seas
will likely remain below SCA levels except for 50-70 percent
chance of SCA level winds across the western portion of the Santa
Barbara Channel each afternoon and evening.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 645-650. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Friday for
      zones 670-673-676. (See LAXMWWLOX).

&&

.HAZARD POTENTIAL OUTLOOK (SAT-WED).

No significant hazards expected.

&&

$$

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

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