Alert archive / Mississippi / Mesoscale Discussions in 2011

Mesoscale Discussion 1856

August 4, 20116 counties in Alabama; 20 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Aug 4, 2011, 3:06 PM CDT for 6 counties in Alabama; 20 counties in Mississippi. It was in force for 54 min.

The area

The outline as issued.

The facts

Issued: Aug 4, 2011, 3:06 PM CDT (20:06 UTC)
Expired: Aug 4, 2011, 4:00 PM CDT
In force: 54 min
Issued by: the Storm Prediction Center

All 26 counties

Colbert County, AL, Fayette County, AL, Franklin County, AL, Lamar County, AL, Marion County, AL, Pickens County, AL, Attala County, MS, Calhoun County, MS, Chickasaw County, MS, Choctaw County, MS, Clay County, MS, Itawamba County, MS, Kemper County, MS, Lee County, MS, Lowndes County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Noxubee County, MS, Oktibbeha County, MS, Pontotoc County, MS, Prentiss County, MS, Tishomingo County, MS, Union County, MS, Webster County, MS, Winston County, MS

The radar

The Columbus AFB radar (KGWX), 37 km from the middle of the area, began a volume at 20:09 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 watches that followed

Watches SPC issued over any of the same counties within four hours of this discussion.

Severe Thunderstorm Watch 727Aug 4, 3:45 PM CDT

The nearest sounding before it

Little Rock, AR (KLZK), launched 12:00Z, 8.1 hours before the alert went out and 159 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: 3023 J/kg
Mixed-layer CIN: -175 J/kg
Mixed-layer LCL: 1991 m above ground
0-6 km bulk shear: 12 kt
0-1 km storm-relative helicity: -18 m²/s²
0-3 km storm-relative helicity: 9 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.

Issued	Product	Office	Counties	Lasted
Aug 3, 10:52 PM CDT	Mesoscale Discussion	SPC	Bibb, Blount, Calhoun, Cherokee, Cleburne, Colbert and 23 more	83 min
Aug 3, 11:59 PM CDT	Severe Thunderstorm Watch	SPC	Bibb, Blount, Calhoun, Cherokee, Clay, Cleburne and 24 more	7 hr
Aug 4, 1:25 AM CDT	Mesoscale Discussion	SPC	Blount, Calhoun, Cherokee, Cleburne, Colbert, Cullman and 18 more	95 min
Aug 4, 12:09 PM CDT	Mesoscale Discussion	SPC	Butler, Choctaw, Clarke, Coffee, Conecuh, Covington and 8 more	66 min
Aug 4, 3:41 PM CDT	Severe Thunderstorm Watch	SPC	Fayette, Greene, Lamar, Marion, Pickens, Sumter	5 hr
Aug 4, 6:06 PM CDT	Mesoscale Discussion	SPC	Colbert, Fayette, Franklin, Greene, Lamar, Lauderdale and 3 more	54 min
Aug 4, 8:06 AM CDT	Severe Thunderstorm Watch	SPC	Alcorn, Benton, DeSoto, Itawamba, Lee, Marshall and 5 more	4 hr

Nearby

Mesoscale Discussions in Mississippi, 2011 Mesoscale Discussions in Alabama, 2011 Every 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.