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Daniel Swain

@weatherwest.bsky.social

2.7k Following46.8k Followers

Weather and climate scientist focused on extreme events like floods, droughts, & wildfires on a warming planet. www.weatherwest.com

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@weatherwest.bsky.socialOct 10, 2026, 6:53 PM

Couple of snapshots of mid-level strato/altocumulus cloud deck arriving in Santa Barbara in advance of Tropical Storm Rachel (late morning on Oct 10). Bands of showers and thunderstorms are already approaching San Diego and Orange counties; main event will be late tonight. #CAwx

Photograph by Daniel Swain showing mid-level strato/alto-cumulus clouds as viewed, looking south from Santa Barbara, on Oct 10.Photograph by Daniel Swain showing mid-level strato/alto-cumulus clouds as viewed, looking south from Santa Barbara, on Oct 10.
@nws.noaa.govOct 10, 2026, 5:53 PMReposted by @weatherwest.bsky.social

Tropical Storm Rachel will bring hazardous conditions to Baja California and the Southwest this weekend, including damaging winds, flash flooding, and life-threatening surf and rip currents. Coastal flooding and erosion are also expected to worsen. hurricanes.gov

National Hurricane Center forecast issued at 11 AM PDT October 10, 2026, showing Tropical Storm Rachel over the Pacific Ocean southwest of Baja California, with maximum sustained winds of 60 mph and moving northeast at 22 mph. Rachel is forecast to approach the northern Baja California coast Sunday morning before weakening to a tropical depression over the southwestern United States by Sunday evening. Tropical storm warnings (blue) and watches (yellow) are in effect for portions of Baja California and Southern California. The white cone shows the probable path of the storm's center, not the full extent of hazardous conditions.
@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

I will be traveling today, but will be monitoring closely. I am still considering the potential for a pop-up livestream either late tonight or early tomorrow AM, but may reserve that option only in the 20% high-impact northern track case (as it will be very late at night!).

@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

It is worth noting that this storm will be entirely unremarkable north and west of Orange County, though cool clouds and some showers and thunderstorms will still be possible elsewhere in SoCal. Extremely dangerous ocean conditions are likely region-wide, however.

@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

"Moderate" coastal flooding (which is actually comparable to or worse than what has already recently been observed) is likely, and there is a slight chance of "major" coastal flooding (with significant damage potential), esp. if Rachel takes the 20% odds northern track tonight.

Screenshot from NWS San Diego discussion of coastal and beach hazards. It begins: Surf of 3-5 feet with local sets to 6 feet will continue on south
and southwest facing beaches through today. Elevated surf and strong
rip and longshore currents will create hazardous swimming
conditions. This elevated surf will combine with high tides near 7
feet during the mornings and evenings to produce significant coastal
flooding and beach erosion.

Fresh south swell associated with Tropical Storm Rachel will arrive
late today into Sunday. This will combine with a larger northwest
swell and strong winds to produce elevated to high surf Sunday for
all area beaches, peaking at 5 to 8 feet with sets to 9 feet. This
will pose a hazard to swimmers and lead to very strong rip currents.
In addition, morning high tides will continue to be 7 to locally 7.5
feet, continuing the threat for significant coastal flooding through
Sunday afternoon. A Coastal Flood Warning is in effect for these
hazards through Sund
@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

In addition, significant coastal flooding and erosion is likely through Monday across SoCal even if Rachel makes landfall in MX. Ocean levels are already running very high due to El Niño, and Rachel will generate high-energy ocean waves from multiple directions.

@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

The biggest threats, regardless, will be from water and not wind (as is almost always the case with tropical cyclones). Inland flash flooding from heavy rainbands is likely from SE CA deserts and eastern mountain slopes northeastward into W. AZ, S. NV, and UT.

Map of flash flood risk from NOAA WPC. Parts of the US SW are depicted as having level 3/4 (moderate) risk--which indicates considerably potential for flash flooding.
@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

The NWS in San Diego has a nice "3 scenario" outline in their AM area forecast discussion, which includes a ~20% likelihood strong wind/heavy rain scenario for San Diego proper, ~20% likelihood of minimal impacts, and ~50% chance of modest impacts.

Screenshot from NWS San Diego discussion. It begins:Scenario #1 (most likely ~ 50% chance): The system reaches land
around 20-100 miles south of the US border, around Ensenada, Mexico.
The low pressure would be close enough to induce gusty winds near
the circulation, especially on the east side of the circulation.
In this case, peak gusts move through the region in the early
hours of Sunday around 25-45 mph through the coastal basin and
50-70 mph near the mountain ridges. Strongest winds would begin
easterly on the SD mountain slopes very early on Sunday, then turn
westerly by sunrise, affecting the ridges and desert slopes.
These gusty winds would continue throughout the afternoon,
weakening by the evening.

Scenario #2 (30% chance): The system makes landfall more than ~100
miles south of the US border. Winds would be much less significant
(gusts < 30 mph) for most of the coastal basin. Winds would remain
westerly everywhere and only pick up by Sunday afternoon with still
very strong
@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

Because of the storm's oblique angle of approach and northeastward acceleration, there remains uncertainty regarding exact point of landfall along Pacific Coast. While somewhere between Tijuana and Ensenada most likely, there's still a ~25% chance of a direct hit near San Diego.

@weatherwest.bsky.socialOct 10, 2026, 4:51 PM

Rachel will make landfall somewhere between Ensenada, MX & USA/MX border late tonight. It should be a strong tropical storm at landfall, w/ gusty/potentially damaging winds & hvy rain (esp. east side of storm). TS Warnings in effect for N. Baja; TS Watch continues for far SoCal.

Official track forecast for Rachel from NOAA National Hurricane Center.
@weatherwest.bsky.socialOct 10, 2026, 4:50 PM

Saturday AM update: Tropical Storm Rachel, despite fairly hostile ambient atmosphere, is indeed strengthening slightly as predicted over record-warm ocean temps & aided by upper-level ventilation from incoming mid-lat trough. Pacific Coast/US SW impacts becoming clearer. [Thread]

@weatherwest.bsky.socialOct 9, 2026, 4:45 PMReposted by @weatherwest.bsky.social

A near-coastal track, in addition to increasing wind threat (mainly San Diego County), would also greatly increase coastal flood/erosion risk more broadly throughout SoCal (since ocean levels are already ~18 inches higher than usual right now).

@weatherwest.bsky.socialOct 9, 2026, 4:45 PMReposted by @weatherwest.bsky.social

The details will depend on the exact track Rachel takes, which will depend on the *exact* degree of re-strengthening of surface low achieves and the exact position of mid-lat trough interaction. But there is potential for Rachel to bring greater wind impacts vs Hilary in 2023.

@weatherwest.bsky.socialOct 9, 2026, 4:45 PMReposted by @weatherwest.bsky.social

A wide range of potential impacts is possible in SoCal, mainly from Orange/San Diego counties south & east, on Sun. There is, however, a growing risk of some notably strong/gusty winds--& ECMWF ensemble now indicates a ~50% chance of wind gusts over 50mph in San Diego. #CAwx

Plot showing ECMWF ensemble maximum wind gusts for a point near the San Diego Airport. At present, nearly 50% of members indicate wind gusts over 50 mph associated with Tropical Storm Rachel.
@weatherwest.bsky.socialOct 9, 2026, 8:52 PMReposted by @weatherwest.bsky.social

Hotel wifi held up! This was recorded live and is now available in case you missed it. I may also do another livestream late Sat night or early Sun morning closer to time of landfall if more northern track materializes...TBD.

@weatherwest.bsky.socialOct 9, 2026, 6:44 PMReposted by @weatherwest.bsky.social

Rapid response blog post on Tropical Storm Rachel and the growing potential for notable Southern California/SW US impacts. Will also be going live on YouTube at Noon Pacific Time (15 minutes!) to discus. #CAwx

@nws.noaa.govOct 9, 2026, 3:45 PMReposted by @weatherwest.bsky.social

There is another tropical system set to impact the West Coast. Tropical Storm #Rachel will be approaching southern California later this weekend. Tropical Storm Watches have been issued for southern California. Get the latest at hurricanes.gov and weather.gov.

Note: The cone contains the probable path of the storm center but does not show the size of the storm. Hazardous conditions can occur outside of the cone.   Details & Current Information:Storm: Tropical Storm Rachel   Date & Time: Friday October 09, 2026, 8 AM PDT Advisory 50   Issuer: NWS National Hurricane Center   Center Location: $22.8^\circ\text{N}, 124.6^\circ\text{W}$   Max Sustained Wind: 50 mph   Movement: NE at 5 mph   Forecast Positions:8 AM Fri: Tropical Storm ('S')   5 AM Sat / 5 PM Sat / 5 AM Sun / 5 PM Sun: Tropical Storm ('S')   Watches & Warnings:Tropical Storm Watch (Yellow): Baja California Peninsula coast and Southern California coastline   Map Description:
Forecast cone showing Tropical Storm Rachel moving northeast from the Eastern Pacific toward the northern Baja California Peninsula and Southern California/Nevada region.  Tropical Storm Watch vs. Tropical Storm Warning

   
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Tropical Storm Watch (Yellow):

   
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A Tropical Storm Watch is issued when tropical storm conditions are possible, typically within 48 hours.

   
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Prepare your home by securing loose items outside or moving them indoors. Have an emergency supply kit ready and charge your devices.   
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+ 1

Tropical Storm Winds Possible.

   
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Tropical Storm Warning (Blue):

   
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A Tropical Storm Warning is issued when tropical storm conditions are expected, typically within 36 hours.

   
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Follow the advice of local officials and be ready to seek shelter in a sturdy structure.   
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Tropical Storm Winds Expected!
@weatherwest.bsky.socialOct 9, 2026, 8:52 PM

Hotel wifi held up! This was recorded live and is now available in case you missed it. I may also do another livestream late Sat night or early Sun morning closer to time of landfall if more northern track materializes...TBD.

@weatherwest.bsky.socialOct 9, 2026, 5:20 PMReposted by @weatherwest.bsky.social

I have finally found an acceptable hotel wifi connection, and will have a short-notice livestream at Noon Pacific Time today (Oct 9) on Tropical Storm Rachel and the growing potential for significant Southern California impacts this weekend. #CAwx

@weatherwest.bsky.socialOct 9, 2026, 6:44 PM

Rapid response blog post on Tropical Storm Rachel and the growing potential for notable Southern California/SW US impacts. Will also be going live on YouTube at Noon Pacific Time (15 minutes!) to discus. #CAwx

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