Alert archive / California / Flash Flood Warnings in 2023

Flash Flood Warning 26, NWS Los Angeles, CA

August 21, 2023San Luis Obispo County, California

NWS Los Angeles, CA issued this flash flood warning at Aug 21, 2023, 3:52 PM PDT for San Luis Obispo 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 21, 2023, 3:52 PM PDT (22:52 UTC)
Expired
Aug 21, 2023, 5:58 PM PDT
In force
2 hr
Issued by
NWS Los Angeles, CA
Area
Storm-based polygon
Damage threat
Considerable
Flood severity
None

County San Luis Obispo County, CA

The radar

The Vandenberg AFB radar (KVBX), 61 km from the middle of the area, began a volume at 22:55 UTC, the scan nearest the moment this went out.

Open the radar archive at this moment

The archived warnings, watches and discussions in force at that minute are drawn over the scan, this one among them.

The nearest sounding before it

Vandenberg AFB, CA (KVBG), launched 12:00Z, 10.9 hours before the alert went out and 73 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-pSkew-T log-p diagram, Vandenberg AFB, CA at 12:00Z on 2023-08-21Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 0 joules per kilogram.LCL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Vandenberg AFB, CA at 12:00Z on 2023-08-21The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 42 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
959 m above ground
0-6 km bulk shear
23 kt
0-1 km storm-relative helicity
42 m²/s²
0-3 km storm-relative helicity
34 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The office that day

Everything else NWS Los Angeles, CA issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 20, 5:25 PM PDTFlash Flood Warning Considerable damage threatLOXVentura2 hr
Aug 20, 5:48 PM PDTFlash Flood Warning Considerable damage threatLOXVentura117 min
Aug 20, 6:29 PM PDTFlash Flood Warning Considerable damage threatLOXLos Angeles10 hr
Aug 20, 7:44 PM PDTFlash Flood Warning Considerable damage threatLOXVentura7 hr
Aug 21, 2:29 AM PDTWind AdvisoryLOXLos Angeles6 hr
Aug 21, 2:54 AM PDTAreal Flood AdvisoryLOXVentura5 hr
Aug 21, 4:13 AM PDTAreal Flood AdvisoryLOXLos Angeles4 hr
Aug 21, 9:11 AM PDTSmall Craft AdvisoryLOX12 hr
Aug 21, 3:00 PM PDTSpecial Weather StatementLOX60 min

Nearby

Flash Flood Warnings in California, 2023Every flash flood warning in 2023

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; radar from the NEXRAD Level II archive.