Another series of inside sliders tracked across the Desert Southwest followed by surface high pressure over the Great Basin. This developed strong Santa Ana winds on February 24th and 25th, and then again on February 27th and 28th.
Every event with a place to put it; 2 filed by county or forecast zone are drawn at its center, in a lighter ring. Tap one for its entry below.
Deaths and injuries are direct and indirect together, as the offices filed them. Damage is property and crops in the dollars of the year, not adjusted for inflation, and only where an office estimated it.
The episode as NWS SGX wrote it up.
Another series of inside sliders tracked across the Desert Southwest followed by surface high pressure over the Great Basin. This developed strong Santa Ana winds on February 24th and 25th, and then again on February 27th and 28th.
The local office's own words before the first event, as it sent them, from the Iowa Environmental Mesonet's archive of National Weather Service text.
NWS San Diego, CA wrote its last area forecast discussion before the first event at Feb 23, 8:38 PM PST, 3 hours 22 minutes earlier.
Area Forecast Discussion
National Weather Service San Diego CA
838 PM PST Tue Feb 23 2021
.SYNOPSIS...
Onshore winds will spread cooling inland through Wednesday. Santa
Ana winds will make a return Wednesday night through Thursday with
strong winds possible below the Cajon Pass into Orange County. This
will warm coastal and valley areas, with cooling elsewhere.
Warmer on Friday, then cooler over the coming weekend with a slight
chance of showers along and west of the mountains Saturday night into
Sunday morning as an upper-level trough moves by to the east. It
will be dry and a little warmer on Monday, before turning cooler
along with a chance of more widespread precipitation mid next week.
&&
.DISCUSSION...FOR EXTREME SOUTHWESTERN CALIFORNIA INCLUDING ORANGE...
SAN DIEGO...WESTERN RIVERSIDE AND SOUTHWESTERN SAN BERNARDINO
COUNTIES...
Skies are clear over SoCal again this evening, but some high clouds
were approaching from the NW and some low, marine clouds are
possible late tonight. The sfc pressure gradient is trending onshore
but is weak and so are most of the wind reports as of 8 PM PST. The
00Z Miramar sounding had a weak inversion near 1375 FT and winds
were light below 4000 FT.
The only potential forecast issue near term is fog. The sfc
dewpoints along the immediate coast have recovered into the 50s.
Onshore sfc pressure gradients to the east are weak, but persistent.
This moist interface could turn to fog along the coast as weak
very dry and rapidly cooling air drains toward the coast. Several
runs of the HRRR are advertising dense fog development over coastal
areas late tonight as well. With that in mind, some dense fog as
been added to the coastal forecast late tonight and Wednesday
morning. A small area of high clouds approaching from the north
should not be significant enough to prevent fog formation, but
could make it difficult to see later tonight if it does. The Zone
Forecasts have been updated to add some fog.
A NW flow aloft will steer several shortwaves over the West this
week, none of which appear to come close enough to SoCal for precip.
They will generate some wind though, particularly on Thursday when
gusty Santa Ana winds are possible, especially over northern parts
of the forecast area. A High Wind Watch has been posted for Wed
evening through Thu afternoon, targeting areas below the Cajon Pass
and the Santa Ana Mts. This will be followed by a weaker wave on
Friday when winds will not be as strong. This dry, and offshore
pattern favors a continuation of above average temperatures for most
areas this week.
A third wave digs south out of Canada over the weekend and could
generate some light precip over SoCal, but chances look slim for
anything meaningful, since it is forecast to track well inland with
limited moisture. Strong and gusty offshore winds could follow for
Sunday.
For next week the forecast picture becomes murky due to a wide
variety of model/ensemble solutions. It does appear there will be
more potential for precipitation as troughing is favored along the
West Coast. Still, the 12Z ensemble member solutions for the
Canadian and the ECMWF are split between dry and wet weather here.
Looks like it will take a bit more time to to see how this will come
together.
&&
.AVIATION...
240400Z...Coastal Areas...Areas of low clouds with bases below 500
ft MSL and vis 2 SM or less developing near the coast after 10Z,
spreading 5 to locally 10 miles inland 12-16Z. Vis at the coastal
airports may be reduced to 1/4-1/2 SM in FG, including KSNA, KCRQ,
and KSAN, though confidence is only moderate. Clouds and vis
restrictions clearing 16-18Z. Patchy low clouds may briefly
redevelop Wednesday evening, quickly clearing Wednesday night as
offshore flow strengthens.
Valleys/Mountains/Deserts...FEW-SCT high clouds AOA 20,000 ft MSL
and unrestricted vis through Wednesday evening.
&&
.MARINE...
Patchy dense fog may develop after midnight with visibility 1 SM or
less. Fog is most likely over the inner coastal waters. Visibility
will improve by mid-morning Wednesday. North to northeast wind
gusts may exceed 20 kt at times Wednesday night through Thursday
morning over northern coastal waters.
&&
.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.
&&
.SGX WATCHES/WARNINGS/ADVISORIES...
CA...High Wind Watch from Wednesday evening through Thursday
afternoon for Orange County Inland Areas-San Bernardino
County Mountains-San Bernardino and Riverside County
Valleys-The Inland Empire-Santa Ana Mountains and Foothills.
PZ...NONE.
&&
PUBLIC...10
AVIATION/MARINE...SSThe national radar mosaic for the moment the first event began.
2 high wind. Local standard time, as filed.
Gusty winds for both events. Fremont Canyon gusted to 81 MPH on the 28th.
Very gusty Santa Ana winds occurred near and below the Cajon Pass. Marshall Peak reported a gust of 98 MPH and CSU-San Bernardino reported a gust of 92 MPH. At least 4 semi trucks were reported over turned on interstates below the Cajon Pass.
After NWS Directive 10-1605, the rules offices file Storm Data by.
Every storm in California in 2021Every state in 2021This day in weather historyWarnings in California, February 2021
NOAA National Centers for Environmental Information, Storm Events Database, compiled from the National Weather Service’s monthly Storm Data. Complete through 2026-06; NCEI adds each month about 75 days after it ends and revises past years a few times a year. Rebuilt 2026-09-24. Each event’s entry at NCEI: 939996, 939993.