So Cal Weather

[WX_Guy]

Good Sunday morning!!! Just a quick weather update to get your week started.

For today through Wednesday, onshore flow will return to SoCal as high pressure aloft weakens. So, a cooling trend can be expected through Wednesday with temperatures dropping to around seasonal normals by Tuesday and Wednesday. Additionally, there will be some coastal stratus/fog developing during the night and morning hours.

For Thursday through next weekend, things could get more “interesting” for SoCal. Both of our main long range computer models are indicating surface high pressure building into the Great Basin on Thursday and Friday. As this develops, Santa Ana wind conditions are likely across the area. At this time, the ECWMF (European) models is noticeably stronger with the offshore pressure gradients, indicating a moderate to strong Santa Ana event. The GFS model is weaker with the offshore gradients, indicating a weak to moderate Santa Ana event. Additionally, as one would expect, these offshore winds will bring much drier conditions to the area with RH dropping into the teens and potentially single digits.

So given the continued critical LFM values, elevated to critical fire weather conditions are likely Thursday through the weekend. At this time, not really confident in the strength of the Santa Ana event for Thursday and Friday, but the potential is there for a significant event.

Please stay tuned to the latest forecasts from the NWS and GACC. As we draw closer to the Thursday/Friday time frame, we will have a much better handle on the potential strength of the event.

Stay safe out there!!!

Wx_Guy

[Contype1]

Looks like weak to moderate Santa Ana Thursday and Friday
https://fsapps.nwcg.gov/psp/sawti
With a fire weather watch
https://forecast.weather.gov/showsigwx.php?warnzone=CAZ048&warncounty=CAC065&firewxzone=CAZ248&local_place1=5%20Miles%20W%20March%20AFB/Riverside%20CA&product1=Fire+Weather+Watch&lat=33.9029&lon=-117.3547

[SIXONENINE]

Red flags now posted for So Cal for a moderate Santa Ana event. Winds could hit 50-60 out of the East. Humidity may drop as low as single digits overnight Thursday into Friday.

[MVUFirePhotographer]

Just to add on to SIXONENINE’s post…Predictive Services has added our 1st “High Risk” days of the fall for most of So Cal. 4 of the next 5 days look interesting for sure.

https://gacc.nifc.gov/oscc/predictive/outlooks/Scal_Fire_Potential.pdf

[SIXONENINE]

Potential wind gusts from the HRRR model:

[TheBrushSlasher]

Red flag warnings issued for the tulare and kern county mountains.

https://forecast.weather.gov/wwamap/wwatxtget.php?cwa=hnx&wwa=red%20flag%20warning

[FireCapt]

NWS - Los Angeles

FIRE WEATHER…10/214 PM

The latest NAM model has a LAX-DAG pressure gradient of -8.3 on Tuesday morning,
which is the strongest pressure gradient of this round of Santa Anas.

Santa Ana conditions will return tomorrow morning across much of
Los Angeles and Ventura Counties with northeast winds kicking in
around 4 am mountains and inland areas then by around 6 am in the **
** coasts and nearby valleys.

Northeast winds will increase in the
mountains to 25 to 35 mph with gusts to 55 mph and localized gusts
to 60 mph in wind prone passes and canyons. For the valleys and
coastal areas, winds of 15-30 mph and gusts to 45 are likely with
some localized gusts to 55 mph possible. Conditions become more
favorable for strong winds as Sunday morning progresses and into
Sunday afternoon. It`s likely that the period from about 10 am
through 4 pm Sunday will have the most intense period for winds
and very low relative humidities for this event.

By late Tuesday afternoon when the red flag warning is
expected to expire at 5 pm. Overall the confidence in timing for **
** this event is high, with moderate-high confidence on wind speeds,
and high confidence on relative humidity forecasts.

[MVUFirePhotographer]

You put this in the CNR weather forum, but then quoted the Los Angeles NWS office.
I just look through the NWS site from LA/Oxnard and saw no mention of the -8.3 gradient

This is what I did find from the fire forecast discussion just issued at 215pm

The LAX-DAG offshore gradient will not be as
impressive as we saw the last few days, but the 24 hour trend from
onshore to offshore flow will be enough to drive the winds. This
should be a moderately strong event with some marginal upper level
support Sunday. There will be the potential for local gusts
around 60 mph in the mountains Sunday.

https://www.wrh.noaa.gov/total_forecast/getprod.php?new&prod=XXXAFDLOX&wfo=lox

[sofr_bear]

Regardless of what weather info is being sent out or who is saying it, best to error on the side of caution and plan for the worse. We have several more days of critical weather and many agencies are close to draw down.

Be safe and PACE

[FSFF]

From NWS S.D. Office:

.DISCUSSION…FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE…
SAN DIEGO…WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES…

…A Dangerous Fire Weather Environment will Exist Across **
** Southern California Sunday-Tuesday as a Strong Santa Ana ****
**** develops…

A shortwave trough over the Pacific Northwest will dive southeast
over the Rockies to New Mexico by early Monday. Strong surface
high pressure will build in behind this upper level feature into
the Great Basin tonight-Sunday with pressure rises into Southeast
California and Arizona Monday-Tuesday. This will set up a tight
surface pressure gradient with offshore gradients 10-11 mb San
Diego to Tonopah, Nevada and an impressive 5-7 mb from San Diego
to Imperial. The result will be a strong Santa Ana wind event
developing.

Winds strengthen tonight and become strong from the San
Bernardino and Riverside coastal mountain slopes and passes into
the Inland Empire (especially northern sections) and to the Santa
Ana Mountain coastal slopes in Orange County. The winds will
strenghten further south into San Diego County (coastal mountain
slopes, foothills and inland valleys).

This will be a multi-day, strong Santa Ana Wind event. Fuels are
already at near their driest for this time of year. We have
had bone dry air in place for days and with more consecutive days
of extremely dry air (relative humidities in the single digits)
ahead, this will make for a potentially dangerous situation. The
mix of strong winds in a desert-like airmass would likely lead to
fast spreading wildfires should fires start. The bone dry air is
forecast to spread all the way to the coast by Monday.

[SIXONENINE]

The first Offshore wind event of the Fall starts tomorrow in So Cal. This event will be weak but will cause winds to gust up to 25-30 in favored spots. Potential wind speeds below.

[Flyron]

SoCal heating up…

https://www.weather.gov/sgx/

[Flyron]

Fire Weather Forecast

[SIXONENINE]

From NWS LA;

And then this possibly around the 28th. We will see if the models keep this in the runs this week.

[Flyron]

[Flyron]

[Flyron]

NWS Satellite view:
https://www.goes.noaa.gov/dml/west/nhem/weus/rb.html

San Diego Area Forecast:
https://www.weather.gov/sgx/

[SIXONENINE]

First moderate to strong Offshore wind event likely next Thursday and Friday. Gust up to 50 mph in the usual spots. Chart showing potential wind speeds below.

[MVUFirePhotographer]

Latest GFS model has backed way off on this already to a very weak event. Time will tell…

[SIXONENINE]

The new 06Z model run shows an eye brow raising off shore event within the next week or so. It looks like we will have on and off east winds for almost 2 weeks. Strength to still be determined. But worth keeping an eye on.