Alert archive / Mississippi / Mesoscale Discussions in 2005

Mesoscale Discussion 937

May 20, 200515 counties in Arkansas; 10 parishes in Louisiana; 20 counties in Mississippi

The Storm Prediction Center issued this mesoscale discussion at May 20, 2005, 4:51 PM CDT for 15 counties in Arkansas; 10 parishes in Louisiana; 20 counties in Mississippi. It was in force for 114 min.

The area

The outline as issued.

The facts

Issued: May 20, 2005, 4:51 PM CDT (21:51 UTC)
Expired: May 20, 2005, 6:45 PM CDT
In force: 114 min
Issued by: the Storm Prediction Center

All 45 counties

Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Cleveland County, AR, Columbia County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Hot Spring County, AR, Jefferson County, AR, Lincoln County, AR, Ouachita County, AR, Union County, AR, Claiborne Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Union Parish, LA, West Carroll Parish, LA, Attala County, MS, Bolivar County, MS, Carroll County, MS, Grenada County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Leake County, MS, Leflore County, MS, Madison County, MS, Montgomery County, MS, Rankin County, MS, Scott County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Warren County, MS, Washington County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 174 km from the middle of the area, began a volume at 21:53 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 304May 20, 5:30 PM CDT

The nearest sounding before it

Jackson, MS (KJAN), launched 12:00Z, 9.9 hours before the alert went out and 164 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: 758 J/kg
Mixed-layer CIN: -68 J/kg
Mixed-layer LCL: 1006 m above ground
0-6 km bulk shear: 28 kt
0-1 km storm-relative helicity: 72 m²/s²
0-3 km storm-relative helicity: 116 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 0.6

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
May 20, 4:18 AM CDT	Mesoscale Discussion	SPC	Clay	57 min
May 20, 5:30 PM CDT	Severe Thunderstorm Watch	SPC	Ashley, Bradley, Calhoun, Chicot, Drew	8 hr
May 20, 12:55 PM CDT	Mesoscale Discussion	SPC	Alcorn, Attala, Benton, Calhoun, Carroll, Chickasaw and 43 more	65 min
May 20, 3:10 PM CDT	Severe Thunderstorm Watch	SPC	Calhoun, Chickasaw, Choctaw, Clarke, Clay, Jasper and 14 more	8 hr
May 20, 6:44 PM CDT	Mesoscale Discussion	SPC	Choctaw, Clarke, Clay, Forrest, George, Greene and 15 more	91 min

Nearby

Mesoscale Discussions in Mississippi, 2005 Mesoscale Discussions in Arkansas, 2005 Mesoscale Discussions in Louisiana, 2005 Every mesoscale discussion in 2005

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.