Alert archive / California / Mesoscale Discussions in 2021

Mesoscale Discussion 1723

September 9, 2021Kern County, San Bernardino County, California

The Storm Prediction Center issued this mesoscale discussion at Sep 9, 2021, 2:44 PM PDT for Kern County, San Bernardino County, California. It was in force for 2 hr.

The area

The outline as issued.

The facts

Issued
Sep 9, 2021, 2:44 PM PDT (21:44 UTC)
Expired
Sep 9, 2021, 4:45 PM PDT
In force
2 hr
Issued by
the Storm Prediction Center
Concerning
Severe potential...watch unlikely
Chance of a watch
5%

Counties Kern County, CA, San Bernardino County, CA

The radar

The Edwards AFB radar (KEYX), 62 km from the middle of the area, began a volume at 21:47 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

Las Vegas, NV (KVEF), launched 12:00Z, 9.7 hours before the alert went out and 215 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, Las Vegas, NV at 12:00Z on 2021-09-09Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 353 joules per kilogram.LCLLFCEL10008507005003002001001 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, Las Vegas, NV at 12:00Z on 2021-09-09The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 27 square meters per square second.1939Sfc1 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
353 J/kg
Mixed-layer CIN
-332 J/kg
Mixed-layer LCL
3002 m above ground
0-6 km bulk shear
28 kt
0-1 km storm-relative helicity
27 m²/s²
0-3 km storm-relative helicity
39 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted.

638 
ACUS11 KWNS 092144
SWOMCD
SPC MCD 092144 
CAZ000-092345-

Mesoscale Discussion 1723
NWS Storm Prediction Center Norman OK
0444 PM CDT Thu Sep 09 2021

Areas affected...Southern California

Concerning...Severe potential...Watch unlikely 

Valid 092144Z - 092345Z

Probability of Watch Issuance...5 percent

SUMMARY...Gusty winds are possible with convection across interior
southern CA into the early evening.

DISCUSSION...Latest satellite imagery suggests a weak mid-level
short-wave trough is located near coastal southern CA, lifting
slowly north around the western periphery of the southwestern US
ridge. This feature appears to be partly responsible for drawing
higher-PW values across the lower CO River valley into southern
interior CA. Strong boundary-layer heating has effectively removed
what inhibition was noted across this region and deep convection is
now evolving within an air mass characterized by up to 1000 J/kg
MLCAPE with cloud bases just above 3km AGL. With PW values near 1.3
inches, local downbursts appear possible given the steep low-level
lapse rates. Isolated strong storms should continue to develop over
the higher terrain and drift north-northwest, aided in part by the
coastal short wave. Strongest convection should remain well
interior.

..Darrow/Grams.. 09/09/2021

...Please see www.spc.noaa.gov for graphic product...

ATTN...WFO...PSR...VEF...SGX...HNX...LOX...

LAT...LON   33781603 34451722 35311874 36061861 35941720 34461490
            33781603

Nearby

Mesoscale Discussions in California, 2021Every mesoscale discussion in 2021

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.