San Dimas, California 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

641
FXUS66 KLOX 211103
AFDLOX

Area Forecast Discussion
National Weather Service Los Angeles/Oxnard CA
303 AM PST Thu Nov 21 2024

.SYNOPSIS...21/154 AM.

Fair skies and dry weather will continue today and most areas
will see some warming as well. Rain chances will develop along the
Central Coast Friday evening then across Los Angeles and Ventura
Counties Saturday. Another round of rain is expected later Sunday
into Monday with lesser possibilities Tuesday.

&&

.SHORT TERM (TDY-SAT)...21/301 AM.

Very pleasent day on tap today (as opposed to the chaos occuring
up north) Srn CA sits under the western half of a weak ridge. At
the sfc there is weak offshore flow from the east and weak onshore
flow to the north. Most areas will warm today and today will be
the warmest day of the next 7 for the csts/vlys.

A cold front will develop in the potent system to the north on
Friday and will begin to move to the south. It will approach the
Central Coast during the afternoon. Some low clouds may develop
across the coasts in the morning but otherwise skies should be
mostly clear through the morning. The afternoon will see an
increase in clouds as the front nears the area. A slight chc of
rain will develop over the coastal section of SLO county later in
the afternoon. Max temps will cool across the csts and vlys but
will warm some across the interior sections of LA county.

The upper low that is driving this cold front and is bringing the
very wet and windy weather to Nrn CA will not move too much to the
south and this means that the cold front will not have that much
dynamics associated with it and that SRN CA will not experience
the dangerous weather that this storm produced to the north.

The front will bring rain to the Central Coast Friday night.
South of Point Conception...rain is likely to develop overnight
across southern SBA county, there wil be a chc of rain for VTA
county and LA county will only have a slight chc.

On Saturday the front will bring rain to SLO/SBA counties in the
morning, it will likely be raining in VTA county and a chc of rain
will extend into LA county. During the afernoon rain is likely
across the entire 4 county area.

Rain is likely across LA county in the evening while the chc of
rain will continue across the rest of the area due to the very
moist (but not very dynamic) moisture plume moving over the area.

Total rainfall for the the Friday night through Saturday evening
period will range from a half inch to an inch across SLO and SBA
counties to a quarter inch to three quarters of an inch for VTA
and LA counties. Some upslope areas may recieve more. The one
likely exception will be the far NW corner of SLO county where as
much as three inches of rain may fall. Rainfall rates are not
expected to be worrisome...about a tenth of an inch or less
except around a quarter inch in upslope areas. Snow levels will
be over 8000 feet so no snow issues expected.

Max temps will fall to their usual rainy day upper 50s and 60s.

.LONG TERM (SUN-WED)...21/300 AM.

Sunday will likely be a mostly dry day, however, there are enough
ensemble members with rain to keep a chc or slight chc (20-30
percent) in the forecast for the day. Skies will likely be mostly
cloudy and max temps will remain in the 60s.

The second impulse of the system is a little trickier to forecast
than the first. It involves the upper low to the north weakening
and wobbling to the south. As it does this it should rotate an
impulse around its backside and into the state. There is a lot of
uncertainty on how this will exactly play out as the ensembles are
all over the place. Right no the mostly likely (but lower
confidence) outcome will be for another round of rain affecting
the area from Sunday night into Monday morning with rain lasting
into Monday afternoon. Rainfall amounts for this system now look
similar to the Friday night Saturday system: generally a quarter
to an inch with locally higher amounts across the upslope areas.
This rainfall forecast has seen many changes over the last few
runs and expect it will change a few more times before the system
arrives. Once again snow levels will be over 8000 feet.

The Tuesday/Wednesday forecast is extremely low confidence as the
mdl are really struggling with pattern that will develop. The
ensembles are all over the place. For now will just broad brush in
some low pops and partly to mostly cloudy skies and hope that
there is some mdl convergence soon.

&&

.AVIATION...21/0902Z.

At 0900Z at KLAX, there was no marine layer. There was a surface
based inversion with a top of 2100 feet and a temperature of
18 degrees Celsius.

Overall, moderate to high confidence in 12Z TAF package. High
confidence in VFR conditions for all sites through this evening.
For tonight, moderate confidence in return of CIG restrictions at
KPRB/KSMX/KSBP, but low confidence in flight category (could range
from MVFR to LIFR). No significant wind issues.

KLAX...High confidence in 12Z TAF. No significant easterly wind
component is expected.

KBUR...High confidence in 12Z TAF.

&&

.MARINE...21/102 AM.

For the Outer Waters, moderate to high confidence in current
forecast. Small Craft Advisory (SCA) level seas will continue
across PZZ670/673 through this afternoon/evening with a 30% chance
of SCA level winds across PZZ670. For late tonight through Friday
night, there is a 20-30% chance of SCA level winds across
PZZ670/673. For Saturday through Monday, high confidence in winds
and seas remaining below SCA levels for all the Outer Waters.

For the Inner Waters north of Point Sal, high confidence in
current forecast. Today through Monday, winds and seas are
expected to remain below SCA levels.

For the Inner Waters south of Point Conception, high confidence in
current forecast. Today through Monday, winds and seas are
expected to remain below SCA levels.

&&

.LOX WATCHES/WARNINGS/ADVISORIES...
CA...High Surf Advisory in effect until 10 AM PST this morning for
      zones 340-346. (See LAXCFWLOX).
     Frost Advisory in effect until 8 AM PST this morning for
      zones 357-371. (See LAXNPWLOX).
PZ...Small Craft Advisory in effect until 9 PM PST this evening
      for zones 670-673. (See LAXMWWLOX).

&&

$$

PUBLIC...Rorke
AVIATION...RAT
MARINE...RAT
SYNOPSIS...MW/Smith

weather.gov/losangeles

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