Alert archive / California / Flash Flood Warnings in 2024

Flash Flood Warning 23, NWS San Diego, CA

August 11, 2024San Diego County, California

NWS San Diego, CA issued this flash flood warning at Aug 11, 2024, 4:11 PM PDT for San Diego County, California. It was in force for 2 hr. No storm report in the archive falls inside the area while it was in force.

The area

The counties it named.

The facts

Issued: Aug 11, 2024, 4:11 PM PDT (23:11 UTC)
Expired: Aug 11, 2024, 6:15 PM PDT
In force: 2 hr
Issued by: NWS San Diego, CA
Area: Storm-based polygon
Damage threat: Considerable
Flood severity: None

County San Diego County, CA

The nearest sounding before it

San Diego, CA (KNKX), launched 12:00Z, 11.2 hours before the alert went out and 47 km from the middle of its area. This is the routine balloon launch nearest before it, the air the forecaster had in hand, not a measurement taken for the alert.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 0 J/kg
Mixed-layer CIN: No buoyant parcel
Mixed-layer LCL: 1769 m above ground
0-6 km bulk shear: 16 kt
0-1 km storm-relative helicity: -34 m²/s²
0-3 km storm-relative helicity: -3 m²/s²
Significant tornado parameter: 0.0
Supercell composite: -0.1

Open this sounding in Storm Lab

What forecasters said that day

The local office's own words before this flash flood warning went out, 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 this flash flood warning went out at Aug 11, 1:57 PM PDT, 2 hours 14 minutes earlier.

Area forecast discussion, Aug 11, 1:57 PM PDT, 2 hours 14 minutes before

Area Forecast Discussion
National Weather Service San Diego CA
157 PM PDT Sun Aug 11 2024

.SYNOPSIS...
Thunderstorms over the mountains, deserts and even the far inland
valleys will gradually dissipate this evening. A slight chance of
thunderstorms returns in southeast San Diego County Monday
afternoon. Dry and seasonal weather is expected into next weekend.
Patchy coastal low clouds and fog will increase Monday and
Tuesday and continue each night and morning.

&&

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

Thunderstorms got started in southern San Diego County before
midday and several other strong thunderstorms have developed over
the mountains. Some of the weakening storms have spilled into the
inland valleys of southern San Diego County. A couple mountain
storms could spill into the adjacent far inland valleys. Some
storms could produce flash flooding and/or strong, gusty winds.
Expect more strong storms to develop and dissipate mainly in the
mountains and adjacent valleys and deserts before finishing up by
sunset. Meanwhile, a coastal eddy has brought some low clouds to
coastal southwest San Diego County, and the coastal cloud coverage
tonight should be more widespread. Temperatures have decreased in
the mountains and deserts compared to yesterday, except the
valleys are just as warm, and it has felt more muggy today in all
areas. The inverted monsoon trough overhead today will fade as a
low pressure trough off the Pac northwest coast will amplify over
the next couple days. This will effectively sweep away the
monsoonal moisture, but enough residual moisture and instability
remain Monday over southeastern San Diego County for a slight
chance of tstorms Monday afternoon. The amplifying trough to the
north will help rebuild the marine layer. Coastal clouds will
become more uniform, extensive and longer lasting, but still
restrained to nights and mornings. The trough will also boost
winds through mountain gaps into deserts during the afternoons and
evenings, with top gusts exceeding 40 mph. Temps will settle down
to around normal. Some model guidance suggests an increase in
monsoonal moisture again next weekend, but no credible chance of
precipitation yet. Expect seasonal and dry conditions to remain
with very little day to day variation this entire week.

&&

.AVIATION...
112234Z...Coast/Valleys...Mostly clear skies with some FEW-SCT
clouds near 20K ft MSL. ISO TSRA drifting into foothills and
adjacent valleys west of the mountains this afternoon and early
evening.

Patchy to areas of low clouds are expected to move into the
coastal areas overnight. Only moderate confidence in timing and
coverage for cigs at coastal TAF sites later tonight, mainly
after 06Z Mon with bases near 1000 ft MSL with tops to near
1200 ft MSL.

Mountains/Deserts...SCT-BKN clouds with bases around 10,000 ft MSL
develop after 16Z, followed by scattered TSRA between 19Z Sunday and
03Z Monday. Gusty and erratic winds possible near storms as well as
MOD UDDFS.

&&

.MARINE...
No hazardous marine conditions are expected through Wednesday.

&&

.SKYWARN...
Skywarn activation is not requested. However weather spotters are
encouraged to report significant weather conditions.

&&

.SGX WATCHES/WARNINGS/ADVISORIES...
CA...None.
PZ...None.

&&

PUBLIC...MM
AVIATION/MARINE...Small

In the hours before

Local storm report, Aug 11, 3:45 PM PDT, 26 minutes before

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Local storm report, Aug 11, 3:46 PM PDT, 25 minutes before

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Local storm report, Aug 11, 3:49 PM PDT, 22 minutes before

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Local storm report, Aug 11, 4:01 PM PDT, 10 minutes before

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Local storm report, Aug 11, 4:03 PM PDT, 8 minutes before

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Local storm report, Aug 11, 4:04 PM PDT, 7 minutes before

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The office that day

Everything else NWS San Diego, CA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Aug 11, 11:50 AM PDT	Areal Flood Advisory	SGX	San Diego	59 min
Aug 11, 12:36 PM PDT	Special Weather Statement	SGX	San Diego	39 min
Aug 11, 12:41 PM PDT	Special Weather Statement	SGX	San Diego	49 min
Aug 11, 12:56 PM PDT	Areal Flood Advisory	SGX	Riverside, San Diego	119 min
Aug 11, 1:02 PM PDT	Severe Thunderstorm Warning	SGX	Riverside, San Diego	58 min
Aug 11, 1:08 PM PDT	Areal Flood Advisory	SGX	San Diego	119 min
Aug 11, 1:36 PM PDT	Special Weather Statement	SGX	San Diego	39 min
Aug 11, 1:48 PM PDT	Areal Flood Advisory	SGX	San Diego	119 min
Aug 11, 1:53 PM PDT	Severe Thunderstorm Warning	SGX	San Diego	67 min
Aug 11, 2:31 PM PDT	Areal Flood Advisory	SGX	San Diego	119 min
Aug 11, 2:53 PM PDT	Flash Flood Warning Considerable damage threat	SGX	San Diego	3 hr
Aug 11, 3:22 PM PDT	Areal Flood Advisory	SGX	San Diego	2 hr
Aug 11, 3:39 PM PDT	Special Weather Statement	SGX	San Diego	36 min

Nearby

Flash Flood Warnings in California, 2024 Every flash flood warning in 2024

Sources

The product and its follow-ups from the Iowa Environmental Mesonet's archive of National Weather Service and Storm Prediction Center text; the sounding from the Mesonet's radiosonde archive.