Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 1852

August 4, 201114 counties in Alabama; Holmes County, Florida; 5 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2011, 12:09 PM CDT for 14 counties in Alabama; Holmes County, Florida; 5 counties in Mississippi. It was in force for 66 min.

The area

The outline as issued.

The facts

Issued
Aug 4, 2011, 12:09 PM CDT (17:09 UTC)
Expired
Aug 4, 2011, 1:15 PM CDT
In force
66 min
Issued by
the Storm Prediction Center

Counties Butler County, AL, Choctaw County, AL, Clarke County, AL, Coffee County, AL, Conecuh County, AL, Covington County, AL, Crenshaw County, AL, Dale County, AL, Escambia County, AL, Geneva County, AL, Henry County, AL, Houston County, AL, Monroe County, AL, Washington County, AL, Holmes County, FL, Clarke County, MS, Greene County, MS, Jasper County, MS, Jones County, MS, Wayne County, MS

The radar

The Mobile radar (KMOB), 127 km from the middle of the area, began a volume at 17:12 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

Birmingham, AL (KBMX), launched 12:00Z, 5.2 hours before the alert went out and 187 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, Birmingham, AL at 12:00Z on 2011-08-04Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 496 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, Birmingham, AL at 12:00Z on 2011-08-04The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity -34 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
496 J/kg
Mixed-layer CIN
-354 J/kg
Mixed-layer LCL
1432 m above ground
0-6 km bulk shear
9 kt
0-1 km storm-relative helicity
-34 m²/s²
0-3 km storm-relative helicity
-66 m²/s²
Significant tornado parameter
0.0
Supercell composite
0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

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SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Aug 3, 10:52 PM CDTMesoscale DiscussionSPCBibb, Blount, Calhoun, Cherokee, Cleburne, Colbert and 23 more83 min
Aug 3, 11:59 PM CDTSevere Thunderstorm WatchSPCBibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 24 more7 hr
Aug 4, 1:25 AM CDTMesoscale DiscussionSPCBlount, Calhoun, Cherokee, Cleburne, Colbert, Cullman and 18 more95 min
Aug 4, 3:06 PM CDTMesoscale DiscussionSPCColbert, Fayette, Franklin, Lamar, Marion, Pickens54 min
Aug 4, 3:41 PM CDTSevere Thunderstorm WatchSPCFayette, Greene, Lamar, Marion, Pickens, Sumter5 hr
Aug 4, 6:06 PM CDTMesoscale DiscussionSPCColbert, Fayette, Franklin, Greene, Lamar, Lauderdale and 3 more54 min
Aug 4, 8:06 AM CDTSevere Thunderstorm WatchSPCAlcorn, Benton, DeSoto, Itawamba, Lee, Marshall and 5 more4 hr

Nearby

Mesoscale Discussions in Alabama, 2011Mesoscale Discussions in Mississippi, 2011Mesoscale Discussions in Florida, 2011Every mesoscale discussion in 2011

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.