Forecast Discussions mentioning any of "ACARS" "MDCRS" "AIRCRAFT" "TAMDAR" "AMDAR" "WVSS" received at GSD on 02/13/22

Area Forecast Discussion

National Weather Service Los Angeles/Oxnard CA

 240 PM PST Sat Feb 12 2022

.SYNOPSIS...12/236 PM.

Unseasonably warm weather will continue this weekend as offshore
flow remains in place. Noticeable cooling will begin Monday, then
much cooler weather is expected Tuesday as a cold storm moves east
of the area. There will be a slight chance of light rain showers
and mountain snow showers Tuesday, along with gusty northwest
winds. Dry conditions with a warming trend is expected for the
remainder of next week, with periods of gusty northeast winds
possible.

&&

.SHORT TERM (TDY-TUE)...12/231 PM.

Significant warmup occurred today across coastal areas of LA/Ventura
counties due to increased offshore flow that enhanced compressional
warming and drying. Record highs of 88 degrees already reached today
at Camarillo Airport and Oxnard, and UCLA at 89 degrees. Other notable
temperatures this afternoon include LAX and Long Beach at 88 degrees,
Hawthorne at 89 degrees, and Downtown LA at 85 degrees. The warmup
across the LA Basin was due to a deep layer of easterly offshore flow
in the boundary layer that was well noted on ACARS soundings this
morning. Also high resolution WRF data captured the easterly offshore
wind component and associated warming to the immediate coast across
LA county.  As of 2 pm, onshore sea breeze and cooling trend making
a return to coastal areas.

Santa Ana winds were generally gusting between 30 and 45 mph this
morning across wind prone areas of LA/Ventura counties. The
LAX-Daggett pressure gradient peaked at -5.3 mb this morning.
Winds are starting to diminish this afternoon, and wind advisories
have been allowed to expire. The upper level wind support and offshore
pressure gradients are expected to be weaker tomorrow, peaking at
around -3.5 mb in the morning. Northeast winds are expected to range
between 15 and 25 mph tonight and Sunday morning in wind favored areas of
LA/Ventura counties. An earlier onset of the sea breeze is expected
on Sunday afternoon across the coastal plain, likely resulting in
a few degrees of cooling from today`s very warm temperatures.
NBM 1-D viewer temperature spreads for the LA coastal zone generally
keeping temperatures in the lower to mid 80s across the LA basin
on Sunday, with some valley locations likely pushing into the upper
80s. These temperatures seem reasonable based on 950 mb temperatures
and timing of sea-breeze. High resolution WRF model showing
sea breeze will return across the LA basin between 1 and 2 pm
tomorrow which will likely usher in a cooling trend during the
mid and late afternoon hours.

A broad upper trough will approach the West Coast Sunday night
and Monday, causing heights and thicknesses across the region to
fall. While gradients will still be weakly offshore Sunday night,
especially across L.A. County, they will turn quickly onshore
on Monday. There may be some return of low clouds to the Central
Coast late Sunday night and Monday, with possibly some dense fog.
Max temperatures will be down several degrees in all areas west of the
mountains on Monday, especially across the coastal plain, with
little change in the mountains, and possibly a touch of warming in the
Antelope Valley. Still, the warmest locations in the valleys could
have highs near 80 degrees on Monday.

The deterministic runs of the GFS, NAM, and the EC have the same general
idea showing an upper low over the Pacific northwest Monday evening
digging southward Monday night and Tuesday. The GFS and EC models
along with the ensemble solutions have tracked further east and drier
with the system on Tuesday. As a result, have trimmed back pops
a bit more for Tuesday, generally in the 15-20 percent range.
And would not be surprised if these pop trends continue to trend
downward for most areas, with the exception of north facing mountain
slopes where there will be some enhanced upslope flow.

.LONG TERM (WED-SAT)...12/234 PM.

The upper low will pull away from the forecast area Tuesday
night, and clouds will decrease. Then, it looks as though it will
be dry Wednesday through Saturday, with periods of gusty north to
northeast winds once again. The EC ensemble max gusts suggest the
peak of the winds will be late Thu into Fri, but at this point,
it looks like just a moderate event. Max temps will rise to above
normal levels by the end of next week, but not nearly to the
levels of this past week and this weekend.

&&

.AVIATION...12/1738Z.

At 17Z at KLAX there was a surface-based inversion. The top of the
inversion was at 1200 ft with a temperature of 24 deg C.

High confidence in VFR conditions across the region through the
fcst period. Gusty NE winds can be expected at KCMA and KOXR thru
early this afternoon.

KLAX...High confidence VFR conditions through the fcst period.
Any E wind component will be 7 kt or less.

KBUR...High confidence VFR conditions through the fcst period.

&&

.MARINE...12/205 PM.

Winds and seas will remain below Small Craft Advisory (SCA) levels
through Sunday night. Moderate confidence in a period of
significant northwest winds over most if not all coastal waters
Monday afternoon through Wednesday as a Pacific system drops into
the region from the north. Winds and seas look most significant
Monday Night through Tuesday, when wind gusts to 35 to 40 knots
are likely and short period seas building up to 8 to 12 feet over
the inner waters and up to 12 to 17 feet over the outer waters.
Steep and dangerous seas for small craft can be expected.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect until 6 PM PST Sunday for zones
      41-547. (See LAXNPWLOX).
PZ...NONE.

&&

.HAZARD POTENTIAL OUTLOOK (TUE-SAT).

Gusty Northwest to north winds are possible late Monday into
Tuesday, strongest across Santa Barbara county and the I-5
corridor. Gusty northeast winds are possible Thursday into
Friday.

&&

$$

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

weather.gov/losangeles

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