Alert archive / Mississippi / Mesoscale Discussions in 2012

Mesoscale Discussion 1860

September 1, 201210 counties in Arkansas; 12 counties in Mississippi; 5 counties in Tennessee

The Storm Prediction Center issued this mesoscale discussion at Sep 1, 2012, 9:59 PM CDT for 10 counties in Arkansas; 12 counties in Mississippi; 5 counties in Tennessee. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Sep 1, 2012, 9:59 PM CDT (02:59 UTC)
Expired: Sep 1, 2012, 11:30 PM CDT
In force: 91 min
Issued by: the Storm Prediction Center

All 27 counties

Calhoun County, AR, Clark County, AR, Cleveland County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Hot Spring County, AR, Lincoln County, AR, Ouachita County, AR, Alcorn County, MS, Benton County, MS, Bolivar County, MS, Coahoma County, MS, Lafayette County, MS, Marshall County, MS, Panola County, MS, Quitman County, MS, Tallahatchie County, MS, Tippah County, MS, Union County, MS, Yalobusha County, MS, Chester County, TN, Decatur County, TN, Hardeman County, TN, Henderson County, TN, McNairy County, TN

The radar

The Little Rock radar (KLZK), 131 km from the middle of the area, began a volume at 02:59 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

Little Rock, AR (KLZK), launched 00:00Z, 3.0 hours before the alert went out and 95 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: 2103 J/kg
Mixed-layer CIN: -34 J/kg
Mixed-layer LCL: 1167 m above ground
0-6 km bulk shear: 27 kt
0-1 km storm-relative helicity: 121 m²/s²
0-3 km storm-relative helicity: 137 m²/s²
Significant tornado parameter: 0.7
Supercell composite: 7.0

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
Sep 1, 7:08 PM CDT	Severe Thunderstorm Watch	SPC	Phillips	6 hr
Sep 2, 3:42 PM CDT	Tornado Watch	SPC	Crittenden, Lee, Phillips, St. Francis	7 hr
Sep 2, 2:20 PM CDT	Mesoscale Discussion	SPC	Alcorn, Benton, Marshall, Tippah, Tishomingo	115 min
Sep 1, 7:56 PM CDT	Mesoscale Discussion	SPC	Carroll, Henry, Weakley	94 min
Sep 2, 2:49 PM CDT	Tornado Watch	SPC	Bedford, Bledsoe, Cannon, Cheatham, Clay, Coffee and 36 more	7 hr
Sep 2, 5:13 PM CDT	Mesoscale Discussion	SPC	Bradley, Hamilton, Loudon, McMinn, Meigs, Monroe and 2 more	62 min
Sep 2, 5:33 PM CDT	Severe Thunderstorm Watch	SPC	Bradley, Hamilton, McMinn, Meigs, Monroe, Polk and 1 more	5 hr
Sep 2, 6:35 PM CDT	Mesoscale Discussion	SPC	Bedford, Cannon, Clay, Coffee, Davidson, DeKalb and 23 more	85 min

Nearby

Mesoscale Discussions in Mississippi, 2012 Mesoscale Discussions in Arkansas, 2012 Mesoscale Discussions in Tennessee, 2012 Every mesoscale discussion in 2012

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.