Alert archive / Alabama / Mesoscale Discussions in 2011

Mesoscale Discussion 634

April 27, 201144 counties in Alabama; 4 counties in Georgia; 32 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 5:01 PM CDT for 44 counties in Alabama; 4 counties in Georgia; 32 counties in Mississippi. It was in force for 89 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 5:01 PM CDT (22:01 UTC)
Expired
Apr 27, 2011, 6:30 PM CDT
In force
89 min
Issued by
the Storm Prediction Center
All 80 counties

Autauga County, AL, Bibb County, AL, Blount County, AL, Butler County, AL, Calhoun County, AL, Cherokee County, AL, Chilton County, AL, Choctaw County, AL, Clarke County, AL, Clay County, AL, Cleburne County, AL, Conecuh County, AL, Coosa County, AL, Cullman County, AL, Dallas County, AL, DeKalb County, AL, Elmore County, AL, Etowah County, AL, Fayette County, AL, Franklin County, AL, Greene County, AL, Hale County, AL, Jefferson County, AL, Lamar County, AL, Lawrence County, AL, Lowndes County, AL, Marengo County, AL, Marion County, AL, Marshall County, AL, Monroe County, AL, Morgan County, AL, Perry County, AL, Pickens County, AL, Randolph County, AL, Shelby County, AL, St. Clair County, AL, Sumter County, AL, Talladega County, AL, Tallapoosa County, AL, Tuscaloosa County, AL, Walker County, AL, Washington County, AL, Wilcox County, AL, Winston County, AL, Bartow County, GA, Floyd County, GA, Haralson County, GA, Polk County, GA, Attala County, MS, Chickasaw County, MS, Choctaw County, MS, Clarke County, MS, Clay County, MS, Covington County, MS, Itawamba County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lee County, MS, Lowndes County, MS, Madison County, MS, Monroe County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Pontotoc County, MS, Prentiss County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Wayne County, MS, Webster County, MS, Winston County, MS

The radar

The Columbus AFB radar (KGWX), 121 km from the middle of the area, began a volume at 22:01 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.

The nearest sounding before it

Jackson, MS (KJAN), launched 12:00Z, 10.0 hours before the alert went out and 154 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, Jackson, MS at 12:00Z on 2011-04-27Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 890 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, Jackson, MS at 12:00Z on 2011-04-27The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 449 square meters per square second.1939587897Sfc1 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
890 J/kg
Mixed-layer CIN
-102 J/kg
Mixed-layer LCL
609 m above ground
0-6 km bulk shear
61 kt
0-1 km storm-relative helicity
449 m²/s²
0-3 km storm-relative helicity
786 m²/s²
Significant tornado parameter
0.0
Supercell composite
21.2

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
Apr 26, 7:59 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lamar, Lauderdale, Lawrence, Limestone and 1 more2 hr
Apr 26, 9:33 PM CDTTornado Watch PDSSPCColbert, Franklin, Lauderdale7 hr
Apr 26, 11:33 PM CDTMesoscale DiscussionSPCColbert, Franklin, Lamar, Lauderdale, Marion117 min
Apr 27, 1:56 AM CDTMesoscale DiscussionSPCBibb, Blount, Cullman, Fayette, Greene, Hale and 12 more64 min
Apr 27, 2:26 AM CDTTornado WatchSPCBibb, Blount, Calhoun, Cherokee, Chilton, Clay and 29 more6 hr
Apr 27, 8:08 AM CDTTornado WatchSPCColbert, Cullman, DeKalb, Fayette, Franklin, Jackson and 10 more6 hr
Apr 27, 10:45 AM CDTMesoscale DiscussionSPCGreene, Lamar, Marion, Pickens, Sumter90 min
Apr 27, 11:39 AM CDTMesoscale DiscussionSPCCullman, DeKalb, Jackson, Madison, Marshall, Morgan66 min
Apr 27, 1:05 PM CDTMesoscale DiscussionSPCBibb, Blount, Calhoun, Cherokee, Chilton, Choctaw and 27 more85 min
Apr 27, 1:42 PM CDTTornado Watch PDSSPCAutauga, Bibb, Blount, Butler, Calhoun, Cherokee and 41 more8 hr
Apr 27, 2:56 PM CDTMesoscale DiscussionSPCBibb, Blount, Calhoun, Cherokee, Chilton, Choctaw and 33 more2 hr
Apr 27, 5:41 PM CDTMesoscale DiscussionSPCBarbour, Bullock, Chambers, Crenshaw, Elmore, Lee and 6 more34 min
Apr 27, 5:52 PM CDTTornado Watch PDSSPCBarbour, Bullock, Chambers, Elmore, Lee, Macon and 5 more9 hr
Apr 27, 6:39 PM CDTMesoscale DiscussionSPCAutauga, Bibb, Blount, Calhoun, Cherokee, Chilton and 26 more66 min
Apr 27, 6:19 AM CDTMesoscale DiscussionSPCBartow, Carroll, Chattooga, Cherokee, Clayton, Cobb and 22 more56 min
Apr 27, 6:48 AM CDTTornado WatchSPCBartow, Butts, Carroll, Catoosa, Chattooga, Cherokee and 36 more2 hr
Apr 26, 9:13 PM CDTMesoscale DiscussionSPCBenton, Bolivar, Coahoma, DeSoto, Marshall, Panola and 3 more62 min
Apr 26, 9:58 PM CDTTornado WatchSPCDeSoto, Tunica7 hr
Apr 27, 4:53 AM CDTSevere Thunderstorm WatchSPCBolivar, Sunflower, Washington5 hr
Apr 27, 6:25 AM CDTMesoscale DiscussionSPCAlcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 33 more65 min
Apr 27, 9:48 AM CDTMesoscale DiscussionSPCClaiborne, Issaquena, Washington27 min
Apr 27, 11:02 AM CDTTornado Watch PDSSPCAdams, Alcorn, Attala, Benton, Bolivar, Calhoun and 63 more8 hr
Apr 27, 6:27 PM CDTMesoscale DiscussionSPCClarke, Clay, Copiah, Covington, Forrest, Jasper and 22 more33 min
Apr 27, 6:42 PM CDTTornado WatchSPCClarke, Covington, Forrest, Jasper, Jefferson Davis, Jones and 13 more3 hr

Nearby

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