Pasadena, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

523
FXUS66 KLOX 021518
AFDLOX

Area Forecast Discussion...UPDATED
National Weather Service Los Angeles/Oxnard CA
818 AM PDT Fri May 2 2025

.SYNOPSIS...02/426 AM.

Expansive marine layer today with another round of afternoon
mountains showers and thunderstorms. Significant cooling and windy
over the weekend, with periods of drizzle or light showers, along
with a slight chance of mountain thunderstorms. Gradual warming
and drying to follow towards the end of next week.

&&

.SHORT TERM (TDY-SUN)...02/428 AM.

The weak upper level low that triggered the showers and
thunderstorms on Thursday will continue to slide to the east and
into Arizona today. While this will lower the instability over the
region, it will still be unstable enough this afternoon and
evening to bring a risk of showers and thunderstorms over the
mountains. Expecting the coverage and severity to be less than
Thursday, but the threat remains for an isolated storm or two
bringing flash flooding to a mountain road or canyon. This
includes some of the burn scars that are in the interior mountains
(not the Palisades or Mountain scars), but the risk for
significant debris flows is tied to the scenario of the strongest
storm of the day forming right over a burn scar...which is
generally a 5% or less chance. With all that stated, most of the
population is in for another gloomy and dreary marine layer kind-
of-day.

Another low pressure system will move through the area over the
weekend. This should rapidly deepen the marine layer on Saturday,
and is cold enough to erode the capping inversion by Saturday
Night. As a result, coastal areas will likely see spots of drizzle
or light rain, especially Saturday morning, and Sunday. The
chances are highest for Los Angeles and Ventura Counties. Any
accumulations will be very light and under 0.10 inches. Over the
mountains and interior areas, off and on again showers will be
common, with lowering snow levels down to around 5,500 feet by
Sunday. Rain and snow amounts will also generally be light, but
there is some instability that will likely result in localized
heavier showers or even a thunderstorm. As a result, some
localized mountain locations could see up to 0.50 inches of rain
and snow in the 2 to 5 inch range.

In addition to the precipitation chances, it will be windy.
Southwest to northwest wind gusts of 25 to 45 mph will be common
over many coastal areas, strongest over the Central Coast and
southwest Santa Barbara Coasts. Some interior valleys, mountains,
and deserts will also see gusts in the 25 to 35 mph range.

Temperatures will plummet, with general highs lowering from the
70 to 80 range today, down to the 60 to 70 range by Sunday which
is around 10 degrees below normal.

.LONG TERM (MON-THU)...02/426 AM.

Some projections keep the low pressure system close enough to
southwest California Monday and Tuesday to keep small chances of
light showers over the region. The general trend however from
Monday through the end of next week is warming and drying, with
highs pushing into the 80s by Thursday. Coastal areas should see a
return of a more traditional May marine layer by Wednesday as the
marine inversion reforms.

&&

.AVIATION...02/1246Z.

At 1208Z at KLAX, the marine layer was 2800 feet deep. The top of
the inversion was 4600 feet with a temperature of 14 Celsius.

Moderate confidence in TAFs through 03Z, then lower confidence.
Timing of flight cat changes could be off by +/- 3 hours. Coastal
sites south of Pt. Conception may struggle to clear this
afternoon and may only clear for a few hours. There is a 30%
chance of KSBP remaining VFR after clearing this morning. There is
a 30% chance of IFR cigs at KPRB after 09Z.

There is another threat of -SHRA and -TSRA this afternoon and
evening, but moderate confidence that it will be less expansive
and staying in the mountains out of any TAF sites.

KLAX...Low to moderate confidence in TAF. Cigs may only clear for
a few hours this afternoon, with timing of flight cat changes off
by +/- 3 hours. Good confidence that any east wind component
remains below 7 kt through the period, with a 6 kt east wind
component possible 12Z-18Z Sat.
KBUR...Low to moderate confidence in TAF. There is a 40% chance of
conds remaining VFR after 08Z. Threat of afternoon -SHRA -TSRA is
extremely low.

&&

.MARINE...02/818 AM.

High confidence in winds and seas remaining relatively benign
this morning. Then, Small Craft Advisory (SCA) winds will become
widespread across the waters this afternoon. There is a moderate
chance for localized GALE force wind gusts in northern portions
of PZZ670 and PZZ645 during the late afternoon/eve hours today.
Winds will then increase to GALE FORCE levels Saturday afternoon,
including the potential for nearshore, with a 40-50% chance of
Gale Force wind gusts continuing across the outer waters into
Sunday evening. There is a low (10%) chance for STORM FORCE winds
in the Outer Waters late Saturday through Sunday. Seas will build
to 10 to 16 feet across the outer waters, with up to 12-14 feet
across the western portion of the inner waters. Conditions will
improve late Sunday into early Monday. Then, sub-advisory
conditions will be common through mid week.

There is a 10 percent chance of thunderstorms across the northern
waters Saturday.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...NONE.
PZ...Small Craft Advisory in effect from 3 PM this afternoon to
      noon PDT Saturday for zones 645-650. (See LAXMWWLOX).
     Gale Watch in effect from Saturday afternoon through Sunday
      morning for zones 645-650-655-670-673-676. (See LAXMWWLOX).
     Small Craft Advisory in effect until noon PDT Saturday for
      zones 670-673-676. (See LAXMWWLOX).

&&

$$

PUBLIC...Kittell
AVIATION...Lund
MARINE...Lewis/Lund/Black
SYNOPSIS...RK

weather.gov/losangeles

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