Newhall, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

274
FXUS66 KLOX 290313
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
813 PM PDT Wed May 28 2025

.SYNOPSIS...28/118 PM.

Dramatic warming is expected late this week for the deserts and
warmest valleys, with above normal temperatures Thursday through
Saturday, peaking Friday. Expect low clouds and fog across the
coast and some valleys each night and morning, becoming confined
to the coastal plains Friday and Saturday.

&&

.SHORT TERM (WED-SAT)...28/812 PM.

***UPDATE***

Latest satellite and surface observations indicate partly cloudy
skies across the area with some stratus across the coastal waters
and the Ventura/LA coastal plain. Current sounding data indicates
marine inversion around 2000 feet in depth. As for winds, some
gusty Sundowner winds (gusts 35-45 MPH) are observed across the
western Santa Ynez Range.

Forecast-wise for the immediate short term, no significant issues
are expected. The Sundowner winds will continue through this
evening, before diminishing overnight. Given the localized nature
of the winds, do not feel the need for any advisories. As for
clouds, skies generally will remain mostly clear to partly cloudy
with some high clouds overnight. Stratus should reform overnight,
mainly impacting the coasts and coastal valleys south of Point
Conception.

Overall, current forecast has great handle on the immediate short
term. So, no significant updates are expected.

***From Previous Discussion***

Synoptically, the area is under an upper-level trough, in which a
cut-off Low has developed about 750 miles to our southwest. The
Low will slowly move southward off the Baja Peninsula and then
return north before exiting to our east on Monday. The Low brings
PWAT values of around an inch to the CWA, so showers (including
thunderstorms) are possible (20%). There is less confidence in
the track of a second cut-off Low that will follow down California
next Tuesday so at this point that could bring more clouds or
some wind. By next Wednesday and Thursday that feature will become
part of a CONUS-spanning upper level trough.

Scattered high clouds cover much of the CWA and low clouds are
persisting at the beaches, especially along the Central Coast.
Little change in temperature today, with highs a few degrees
warmer in far interior locations, and a near normal to slightly
below elsewhere under the clouds.

Thursday into the weekend, the low pressure system will separate
from the the steering flow and stall off the coast of Baja
California, well south of the region. Concurrently, a broad ridge
of high pressure will set up over the western United States. The
precise location of this cutoff low will have significant impacts
on high temperatures. Regardless, substantial warming is expected
Thursday and Friday. Peak 500 mb heights and light offshore winds
will make Friday the warmest day, with temperatures around 10 to
18 degrees above normal. Highs are likely to be in the mid 70s to
mid 80s at the beaches, upper 80s to mid 90s for inland coastal
plains/valleys and lower mountains, and up to around 104 for the
deserts and inland San Luis Obispo County. Areas of gusty (but
sub-advisory) north to northwesterly winds will occur tonight
through Thursday night as the low passes by the region, most
notably for southwest Santa Barbara County and the Interstate 5
Corridor.

There is a Heat Advisory for Friday across interior San Luis
Obispo and Santa Barbara Counties. Some calender day records will
be in play Friday, most notably for Paso Robles where the current
daily record is 102. South of Point Conception, there is still a
chance for Heat Advisories on Friday for some valley locations,
but the outlook is cooler than it had been in previous model runs.
The high pressure aloft will compress the marine layer, thus
clouds will be mostly confided to the coastal plains on Friday.
Dense fog will be possible in the shallow marine layer, including
for the coastal waters, most likely Friday night into Saturday
morning.

On Saturday, 500 mb heights are expected to drop slightly and
onshore flow will also increase, so widespread cooling of 2 to 6
degrees is likely. There is a significant spread between ensemble
members for Friday, thus a greater drop in temperatures is
possible, as well as no cooling at all for areas south of Point
Conception. Moisture pumped into the area from the Low should
lead to cloud buildup over the mountains and could lead to some
showers later in the day.

.LONG TERM (SUN-WED)...28/126 PM.

Early Sunday through Monday the cutoff low is favored to move in
a northeast direction, crossing over land just south of the CWA.
This will cause 500 mb heights to fall rapidly and bring southerly
flow, moisture, and instability to the area. Currently there is
around a 10 to 20 percent chance of showers or thunderstorms late
Saturday afternoon through Sunday night, focused south of Point
Conception, where PWATs may exceed 1 inch. The greatest chance of
convection will be over the mountains of LA and Ventura Counties.

Max temperature will cool Saturday through Monday, becoming
widespread below normal on Monday, when strong onshore flow is
expected.

By Tuesday, overall low pressure wSTDAFDLOXill continue as an unseasonably
strong trough is favored to drop into the region. The cooling
trend will continue, becoming 5 to 10 degrees below normal on
Tuesday, when most areas will see highs between 63 and 73 degrees.
Gusty winds are likely with this pattern, and there is a slight
chance of showers and thunderstorms for the mountains and north-
facing foothills. There is considerable uncertainty in the axis
of the trough.

On Wednesday the CWA will be on the southwest base of a CONUS-
spanning trough. Heights will rise as the feature moves eastward
kicking off a warming trend that should last through next week.

&&

.AVIATION...29/0109Z.

Around 0031Z, the marine layer was 2100 feet deep at KLAX. The
top of the inversion was around 4800 feet with a temperature of
19 C.

Overall, moderate confidence in the 00Z TAF Package. Most
confident in fcsts for desert terminals, and lowest for coastal
and valley sites. IFR conds expected for the overnight period for
terminals from KSBA to KSBP, generally after 03Z but timing could
differ by up to 2 hours from TAF times. There is a 30% chance that
KSBP remains clear. Moderate to high confidence in MVFR cigs
returning to LA/Ventura county terminals tonight.

KLAX...Moderate to high confidence in the 00Z TAF. MVFR cigs
are expected to persist through the overnight period, with
clearing by 21Z. Clearing time could differ by +/- 2 hours. No
significant east wind component expected.

KBUR...Moderate confidence in the 00Z TAF. There is a 30% Chance
of CIGs as early as 08Z Thu, with a 30% chance of IFR conds.
Arrival and departure times of cigs may be off +/- 2 hours.

&&

.MARINE...28/746 PM.

For the outer waters moderate to high confidence in SCA
conditions through Thursday night. There is potential (50-60%
chance) that GALE force wind gusts will become widespread across
PZZ670/673 and western portions of PZZ676 on Thursday during the
late afternoon and overnight hours. Conditions should be below
SCA levels Friday afternoon through Saturday, with increasing
chances for SCA winds and seas into early next week. Higher
confidence in seas reaching SCA levels.

For the nearshore waters along the Central Coast, there is a
60-80% chance of SCA level seas through the late night hours.
There may be a lull in winds Thursday morning, before increasing
to SCA levels by Thursday afternoon, with a 40-60% chance of Gale
Force gusts in the late afternoon and evening hours. Conditions
are generally expected to remain below SCA criteria through the
weekend. Potential for SCA winds and seas early next week.

For the Santa Barbara Channel, there is a 10-20% chance of SCA
level wind gusts for western portions of the channel Thu
afternoon/eve. Moderate-to-high confidence in conds remaining
below SCA levels for the weekend.

For the Inner Waters off the Los Angeles and Orange County coasts,
moderate-to-high confidence in conditions remaining below SCA
levels through Sunday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 11 AM to 8 PM PDT Friday for
      zones 38-343>345. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 3 AM PDT Thursday for
      zones 645-670-673-676. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through Thursday
      evening for zone 645. (See LAXMWWLOX).
     Gale Watch in effect from Thursday afternoon through late
      Thursday night for zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Schoenfeld/jld/Thompson
AVIATION...Ciliberti
MARINE...Ciliberti
SYNOPSIS...jld

weather.gov/losangeles

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