Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 06/26/22

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 834 PM PDT Sat Jun 25 2022

.SYNOPSIS...25/832 PM.

Strong upper level high pressure will bring limited night and
morning marine layer clouds and fog to coastal areas into early
next week, otherwise skies will be mostly clear. It will also be
quite hot away from the coast each day through Tuesday with many
areas reaching the 90s to low 100s, except to as high as 107
degrees in some interior valleys on Monday. Overnight lows will
also be quite warm which will add to the heat stress. A gradual
cool down is expected mid to late next week.

&&

.SHORT TERM (SAT-TUE)...25/831 PM.

Upper level ridge of high pressure will build across Southwest
California through Monday, with continued hot and dry conditions
across inland areas. Some of the warmest inland locations topped
100 degrees once again today, with Woodland Hills coming in at 102
degrees, Lancaster at 101, and Chatsworth, Northridge, and Paso
Robles observing 100 degrees. A shallow marine layer depth will
continue to moderate coastal areas. Latest ACARS soundings showing
marine layer depth around 800 feet across the LA Basin, and
further lowering is possible by morning. Satellite imagery showing
low clouds and fog rolling back into some of the coastal areas
this evening, and will most likely remain confined to the coastal
plain overnight due to the shallow marine inversion. With a low
and strong inversion in place, there is also the potential for
patchy dense fog tonight and again Sunday night, which may require
dense fog advisories.

The main story the next couple of days will be the hot
temperatures and low humidities across inland areas through
Monday. Most inland areas will likely see 2-3 degrees of
additional warming on Sunday with highs generally ranging between
95 and 105 degrees for many valley, lower mountain, and desert
locations. Monday could see another degree or two of additional
warming across inland areas. Coastal areas will be much cooler
with highs from the upper 60s to low 70s at the beaches to the 80s
inland.

The forecast hot temps has prompted the issuance of a Heat
Advisory Sun and Mon for many inland areas in SLO/SBA Counties as
well as the VTU County mtns and the vlys and mtns of L.A. County.
Hot conditions Mon has resulted in the issuance of a Heat Advisory
for the VTU County central and southeastern valleys as well as
the Santa Monica Mtns. Please see the latest Non-Precipitation
Weather Message (LAXNPWLOX) for further details. While areas
south of Point Conception will likely see some cooling on Tuesday,
a slight offshore wind component Tuesday morning may maintain
very warm temperatures across interior areas of SLO county into
Tuesday afternoon, which may prompt the extension of the heat
advisory for SLO county interior valleys/mountains. The hot
temperatures and low humidities (including poor overnight
recoveries) will bring an increased risk of fire activity
across inland areas on Sunday and Monday,

*** Previous discussion ***

Pressure gradients are forecast to be weaker onshore with
offshore trends tonight thru Mon, then there will be very weak
onshore pressure gradient trends Mon night into Tue. This combined
with 950 mb temps in the 30-35 deg C range each day, except up to
36-37 deg C for far interior areas, and a strong and shallow
inversion, will result in temperatures increasing even further
away from the coast to about 5-15 deg above normal Sun, 6-16 deg
or more above normal Mon, and 4-14 deg above normal Tue. Highs
over the hottest vlys and lower mtns are expected to top out in
the 95-105 deg range on Sun and Tue, and 97-107 deg range on Mon.
Overnight lows will also be quite warm especially for the warmest
vly and foothill areas, with temps remaining in the 70s. The
warmest foothills may not even drop below 80 degrees Sun night.

Beyond increased heat stress potential during this period,
elevated fire weather conditions will also be in place due to hot
and dry conditions.

.LONG TERM (WED-SAT)...25/222 PM.

Ensemble (GEFS, EPS, GEPS) and deterministic fcsts are in good
agreement on synoptic scale features. Upper level ridging will
persist into Wed with H5 heights over the area around 591-592
dam. The ridging will slowly weaken Thu thru Sat as a broad upper
level trof moves into the E Pac. H5 heights will slowly lower from
589-590 dam on Thu to 587-589 dam on Sat. A broad and dry SW flow
aloft can be expected thru the extended period.

A generally benign weather pattern can be expected Wed thru Sat.
The marine inversion should slowly increase thru the period, along
with gradually increasing onshore gradients. Varying amounts of
night and morning low clouds and fog can be expected along the
coast and into some of the adjacent vlys, with the least amount of
low clouds Wed morning, expanding along the coast and into some of
the adjacent Thu thru Sat. Temps will still be several degrees
above normal Wed, then cool to near normal Thu and a few degrees
below seasonal norms for many areas Fri and Sat.

&&

.AVIATION...26/0012Z.

At 0005z at KLAX, the marine layer was 800 feet deep. The top of
the inversion was 1900 feet and 27 Celsius.

High confidence in VFR conditions over KPRB KBUR KVNY KWJF KPMD
with typical onshore winds.

Moderate confidence in similar conditions over the next 24 hours
as previous, with slight lowering of CIGS VIS tonight/Sun
morning. IFR/LIFR flight cats will be very common. Typical onshore
winds expected, except for high chance of brief hot day NW wind
at KVNY late afternoon/early evening hours.

KLAX...Based on satellite trends, have moved up timing a couple
hours for IFR cigs, most likely arriving around 02z. Moderate
confidence in OVC004-006 continuing through 17Z Sat. Low
confidence on when clouds will return. High confidence that any
SE wind will stay under 07 knots early Sunday morning.

KBUR...High confidence in VFR through at least Sunday with
typical onshore winds.

&&

.MARINE...25/817 PM.

Small Craft Advisory level gusts can be expected at times
overnight across the southern two outer waters zones. Otherwise,
moderate to high confidence that winds and seas will remain below
Small Craft Advisory (SCA) levels across the coastal waters
through the weekend. Moderate confidence (40%-50% chance) that SCA
level NW winds will return to the outer coastal waters Sunday
night, with higher probability Monday through Thursday. SCA wind
gusts at times are also possible (30%-40% chance) Monday night
through Thursday for the inner waters N of Point Sal, and on
Thursday for the western Santa Barbara Channel portion of the
southern inner waters.

A shallow marine layer will likely bring areas of dense fog with
visibility of one nautical mile or less across much of the coastal
waters each night and morning through Monday, with patchy dense
fog possible Monday night into Tuesday morning. Marine Weather
Statements for dense fog will be needed tonight and likely Sunday
night.

A 12-14 second period south swell of 2-4 feet is expected to
build into the waters early next week from Tropical Storm Celia,
likely peaking Tuesday evening through Wednesday afternoon.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 10 AM Sunday to 8 PM PDT Monday
      for zones 53-54-88-343>345-353-547-548. (See LAXNPWLOX).
     Heat Advisory in effect from 10 AM to 8 PM PDT Monday for
      zones 358-359-363. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Sunday for
      zones 673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Gomberg/Sirard
AVIATION...Gomberg
MARINE...Sirard
SYNOPSIS...Sirard

weather.gov/losangeles

Experimental Graphical Hazardous Weather Outlook at:
https://www.weather.gov/erh/ghwo?wfo=lox