Alert archive / Mississippi / Mesoscale Discussions in 2011

Mesoscale Discussion 639

April 27, 201128 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at Apr 27, 2011, 6:27 PM CDT for 28 counties in Mississippi. It was in force for 33 min.

The area

The outline as issued.

The facts

Issued
Apr 27, 2011, 6:27 PM CDT (23:27 UTC)
Expired
Apr 27, 2011, 7:00 PM CDT
In force
33 min
Issued by
the Storm Prediction Center
All 28 counties

Clarke County, MS, Clay County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Lowndes County, MS, Marion County, MS, Monroe County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Walthall County, MS, Winston County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 46 km from the middle of the area, began a volume at 23:31 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, 11.5 hours before the alert went out and 55 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 DiscussionSPCAlcorn, Attala, Calhoun, Carroll, Chickasaw, Choctaw and 26 more2 hr
Apr 26, 9:13 PM CDTMesoscale DiscussionSPCBenton, Bolivar, Coahoma, DeSoto, Marshall, Panola and 3 more62 min
Apr 26, 9:33 PM CDTTornado Watch PDSSPCAlcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 41 more7 hr
Apr 26, 9:58 PM CDTTornado WatchSPCDeSoto, Tunica7 hr
Apr 26, 11:33 PM CDTMesoscale DiscussionSPCAlcorn, Attala, Benton, Bolivar, Calhoun, Carroll and 42 more117 min
Apr 27, 1:56 AM CDTMesoscale DiscussionSPCClarke, Copiah, Covington, Jasper, Jefferson Davis, Kemper and 11 more64 min
Apr 27, 2:26 AM CDTTornado WatchSPCAdams, Alcorn, Attala, Calhoun, Chickasaw, Choctaw and 38 more6 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, 8:08 AM CDTTornado WatchSPCAlcorn, Calhoun, Carroll, Chickasaw, Choctaw, Clay and 16 more6 hr
Apr 27, 9:48 AM CDTMesoscale DiscussionSPCClaiborne, Issaquena, Washington27 min
Apr 27, 10:45 AM CDTMesoscale DiscussionSPCAdams, Attala, Benton, Calhoun, Carroll, Chickasaw and 53 more90 min
Apr 27, 11:02 AM CDTTornado Watch PDSSPCAdams, Alcorn, Attala, Benton, Bolivar, Calhoun and 63 more8 hr
Apr 27, 1:42 PM CDTTornado Watch PDSSPCGreene, Perry, Wayne8 hr
Apr 27, 2:56 PM CDTMesoscale DiscussionSPCAlcorn, Attala, Calhoun, Chickasaw, Choctaw, Clarke and 35 more2 hr
Apr 27, 5:01 PM CDTMesoscale DiscussionSPCAttala, Chickasaw, Choctaw, Clarke, Clay, Covington and 26 more89 min
Apr 27, 6:42 PM CDTTornado WatchSPCClarke, Covington, Forrest, Jasper, Jefferson Davis, Jones and 13 more3 hr

Nearby

Mesoscale Discussions in Mississippi, 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.