Willow Brook, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

607
FXUS66 KLOX 041728
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
928 AM PST Wed Dec 4 2024

.SYNOPSIS...04/215 AM.

Above normal temperatures are expected through the week, peaking
Friday and Saturday with highs in the 70s and 80s. Locally gusty
Santa Ana winds are possible Friday into early next week. Skies
will be mostly clear to partly cloudy with areas of morning low
clouds and fog at times. No rain expected through the end of next
week.

&&

.SHORT TERM (TDY-FRI)...04/837 AM.

***UPDATE***

Latest satellite and surface observations indicate stratus/fog
across the coastal plain and lower coastal valleys with clear
skies elsewhere. Current sounding data indicates marine inversion
ranging in depth from 800 feet north of Point Conception to about
1400 feet across the LAX Basin. As for winds, some very localized
northerly winds, gusting 20-25 MPH, across the mountains.

Forecast-wise for the immediate short term, no issues are
expected. Current blanket of stratus/fog should dissipate by late
morning although clouds could linger across beach areas through
the afternoon. Otherwise, skies should remain mostly sunny through
the day. No significant wind issues are expected to develop.

Overall, current forecast has great handle on the immediate short
term. So, no significant updates are expected. For the afternoon
forecast suite, attention turns to periods of offshore winds.

***From Previous Discussion***

Not much weather excitement in short term. A high hgt upper low
sits under a large west coast ridge and over Srn CA. On Thursday
and Friday the pattern transforms into one with a east Pac ridge
nosing into Nrn CA and the upper low now over srn AZ. At the sfc
weak onshore flow today will transition to weak offshore flow Thu
and stronger offshore Fri.

The marine layer this morning is under a 1000 ft and it has
produced some dense fog along with the coastal and lower vly low
clouds. There will be less low clouds Thursday and then likely
mostly clear skies on Friday as the offshore flow really kicks
into gear.

Just light winds today. There will be some 15 to 25 mph canyon
winds on Thursday with the weak offshore flow. There is a 40
percent chc of advisory level gusts (35 to 45 mph) Friday morning
as the upper level flow aligns with the NE offshore flow at the
sfc.

Many areas will see max temps rebound 2 to 4 degrees from ydy`s
temps esp near the coast. Max temps today will be 4 to 8 degrees
above normal away from the coast, but the marine layer will keep
the coasts a few degrees blo normal. The coasts and vlys will warm
noticeably each day while the interior cools as colder air from
the interior advects in. By Friday almost all of the csts/vlys
will see max temps in the 70s with a smattering of lower 80s in
the warmest locations. Friday`s temps will be 5 to 10 degrees
above normal over most of the area.

.LONG TERM (SAT-TUE)...04/328 AM.

Saturday will likely be a near repeat of Friday with clear skies
and a weak to moderate Santa Ana in the morning. Max temps will
again top out 5 to 10 degrees over normal.

A trof rolls out of the PAC NW on Sunday and pushes the ridge to
the south and east. More importantly the offshore flow flips to
onshore. There may even be some low clouds in the morning (best
chc across the Central Coast). Most areas will cool 3 to 6
degrees.

A little change in the Mon/Tue fcst as now only a trof is forecast
to move down the CA/NV state line and not an upper low. This will
limit the upper and thermal support for the offshore event.

Offshore conditions are still forecast for both Mon and Tue.
Monday looks like more of an north wind event with the N/S
gradient forecast at 5 mb offshore but the W/E push only at 2 mb.
Tuesday looks like the windiest day as there is about 40 mph of
850 mb wind support and the offshore grads between 4 and 6 mb in
both directions. If these values hold up it will produce advisory
level gusts. The cool air advection will overwhelm the
compressional warming on Monday and most area will cool with the
interior of LA and VTA counties cooling the most. The interior
will cool a few more degrees on Tuesday with other temps holding
pretty steady. MAx temps across the csts/vly will mostly be in the
60s.

Lots of disagreement on the Wednesday forecast. It will be dry.
Most ensemble members favor some warming which is what the
deterministic EC is showing.

&&

.AVIATION...04/1727Z.

At 1647Z at KLAX, the marine layer was 1400 feet deep. The top of
the inversion was at 3800 ft with a temperature of 16 C.

High confidence in TAFs for KPRB, KPMD, and KWJF.

Low to moderate confidence in remaining TAF sites. There is a 40%
chance for VLIFR conds at KBUR and KVNY. However, there is also a
30% chance cigs and limited vsbys don`t reach KBUR and KVNY
tonight if offshore flow establishes itself. For all coastal
sites, timing of cig arrivals may be off by +/- 3 hours and lowest
flight cat may be off by one. For sites south of Point
Conception, there is a 30-40% chance that cigs do not clear this
afternoon.

KLAX...Low confidence in TAF. There is a 30% chance that cigs
will not clear this afternoon. Otherwise, clearing and arrival
times of cigs may be off by +/- 2 hours. There is a 20% chance for
OVC001-002 and vsbys between 1/4SM and 1/2SM between 07 and 15Z.
No significant east wind component is expected.

KBUR...Low confidence in TAF. Timing of cig arrival tonight may be
off by +/- 3 hours. There is a 40% chance for VLIFR conds once
cigs arrive. However, there is also a 30% chance cigs and limited
vsbys don`t arrive tonight if offshore flow establishes itself.

&&

.MARINE...04/751 AM.

In the Outer Waters, there is a 30% chance of Small Craft
Advisory (SCA) level wind gusts this evening though Thurs morning.
SCA level winds are likely (60-70% chance) Thu afternoon into Thu
night, then there is a 40-60% chance of SCA level winds Fri and
Sat, with best chances in the afternoon and evening hours. Seas
will begin to build Sun and Mon across the Outer Waters, likely
(60-70% chance) reaching SCA levels. During the aforementioned
time period, there is a 40-50% chance of SCA level winds.

In the inner waters north of Pt. Sal, and in the inner waters
south of Point Conception, SCA conds are not expected, except for
a 30% chance of SCA level NE winds nearshore from Ventura to Santa
Monica during the late night thru morning hours Thu night thru Sat.

Areas of dense fog will affect the coastal waters through late
this morning, with patchy night through morning low clouds and
fog likely thru Fri.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...NONE.

&&

$$

PUBLIC...Rorke/Thompson
AVIATION...Lewis
MARINE...DB/Lewis
SYNOPSIS...MW

weather.gov/losangeles

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