Atascadero, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

961
FXUS66 KLOX 200427
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
927 PM PDT Mon May 19 2025

.SYNOPSIS...19/732 PM.

A ridge of high pressure will result in an extended period of
hot weather this week, peaking on Wednesday and Thursday. High
temperatures will be well above normal. Gusty winds are expected
across southern Santa Barbara County and in the Los Angeles County
Mountains near the Grapevine.

&&

.SHORT TERM (MON-THU)...19/915 PM.

***UPDATE***

Temperatures warmed significantly today as high pressure built
over the region. The lack of marine layer clouds contributed to
the rapid warming, along with offshore northeasterly winds. The
valleys and portions of the Central Coast were up to 10-20 degrees
warmer than yesterday, with highs in the 80s to low 90s. Many
coastal zones and mountains were cooler, reaching the upper 60s to
70s. Looking into Tuesday and Wednesday, temperatures will
continue to rise as these northerly winds continue and the high
pressure center pushes closer to southern California.

Tonight, there is a slight chance for some marine layer clouds and
fog to redevelop over the coastal waters, and these may affect
coastal areas briefly Tuesday morning. It wouldn`t be surprising
to see low clouds and haze lingering at the beaches earlier
Tuesday, and Wednesday given the shallow marine layer depth.
Otherwise, the current forecast looks on track, with no
significant changes needed.

***From Previous Discussion***

The warming trend is in full swing today with most areas away from
the immediate coast up 5-15 degrees from yesterday and some areas
as much as 20 degrees warmer. Pressure gradients continue to trend
offshore as well which is providing another source of warming in
addition the building ridge aloft. With those offshore gradients
will also come some gusty winds in the mountains, strongest
overnight tonight into Tuesday morning. Winds may approach
advisory levels at times due to moderate descending flow, but
winds between 900 and 500mb are relatively light as are the
gradients so advisory level winds should be very marginal and
mostly in unpopulated areas.

Warmest temperatures this week will be Tuesday through Thursday.
Models have definitely trended "not as hot" but even with the 2-4
degree downward adjustment to the forecast high temperatures,
when factoring in the warming overnight lows and very light
offshore flow, heat risk values still reach advisory levels
across a large portion of the valleys and lower mountains,
including the Santa Ynez and southern Salinas Valleys as well.
However, confidence isn`t super high, and if models continue to
trend lower with temperatures tonight and tomorrow it`s possible
some of the more marginal areas such as Downtown LA, may drop off
the advisory.

.LONG TERM (FRI-MON)...19/200 PM.

Good mdl agreement that a trof will ripple through the state on
Friday. Hgts will not fall too much only about 2 dam. More
importantly there will be strong onshore trends leading to mdt to
stg onshore flow both to the north and east in the afternoon. The
increased onshore flow and cyclonic turning aloft will produce an
abundance of morning low clouds that will cover most of the csts
and some of the lower vlys. Almost all areas will see 3 to 6
degrees of cooling. Still with cstl highs mostly in the mid 70s to
lower 80s and the vlys coming in the upper 80s to lower 90s, max
temps will remain well above normal.

The real cooling will hit Saturday as hgts fall and onshore flow
remains strong. Coastal low clouds are likely although many
ensembles show slightly less coverage than on Friday. The big news
will be the temps: look for 5 to 10 locally 12 degrees across the
area. The biggest cooling will occur in the LA/VTA vlys. Max temps
will drop to a few degrees either side of normal.

Slightly higher hgts and slightly less onshore flow will bring a
few degrees of warming to the area on Sunday.

&&

.AVIATION...20/0217Z.

At 2358Z at KLAX, the marine layer was around 1000 feet deep. The
top of the inversion was 2500 feet with a temperature of 24 C.

High confidence in all TAFs. There is a 10-20% chance of MVFR vis
and/or cigs at KLAX, KSMO, KOXR, KSBA and KSMX from 12Z-17Z Tue.

KLAX...High confidence in TAF. There is a 20% chance of 3-5 SM BR
and BKN005-BKN010 conds 12Z-17Z Tue. No significant east wind
component is expected.

KBUR...High confidence in TAF.

&&

.MARINE...19/731 PM.

Moderate to high confidence in the current forecast. Higher
confidence exists in the forecast for seas relative to the
forecast for winds.

For the Outer Waters and the nearshore waters along the Central
Coast, conditions will be at least Small Craft Advisory (SCA)
levels through Tuesday night, except for lulls nearshore along
the Central Coast during late night and early morning hours. There
is a 60-90 percent chance for GALE Force winds late this
afternoon through this evening, decreasing to a 60-80 percent
chance of Gales Tuesday through Tuesday night. The highest
chances for Gale Force winds will be for the majority of the Outer
Waters, while the lowest chances will be for the nearshore waters
along the Central Coast and the for southern Outer Waters. There
remains a moderate to high chance for GALE Force winds through the
work week, but low confidence in timing and max wind speeds
beyond Tuesday.

Across the Santa Barbara Channel, there is a 40-60 percent chance
of SCA level winds tonight across the western portion, followed
by a 40-60 percent chance on Tuesday afternoon and night. There
are lesser chances for Wednesday and Thursday afternoons and
evenings.

South of Point Mugu, into the Santa Monica Bay, and the San Pedro
Channel, winds and seas are expected to remain below SCA levels
through at least Thursday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...Heat Advisory in effect from 11 AM Wednesday to 9 PM PDT
      Thursday for zones
      88-343-348-351>353-356>358-368-374-375-548. (See LAXNPWLOX).
     Heat Advisory in effect from 11 AM Tuesday to 9 PM PDT
      Thursday for zones 369>373. (See LAXNPWLOX).
PZ...Gale Watch in effect from Tuesday afternoon through Tuesday
      evening for zone 645. (See LAXMWWLOX).
     Small Craft Advisory in effect until 3 AM PDT Tuesday for
      zone 650. (See LAXMWWLOX).
     Gale Warning in effect until 3 AM PDT Wednesday for zones
      670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Phillips/MW
AVIATION...Phillips
MARINE...Hall/Lund/Ciliberti
SYNOPSIS...KL/Ciliberti

weather.gov/losangeles

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