Alert archive / Arkansas / Mesoscale Discussions in 2004

Mesoscale Discussion 418

April 21, 200431 counties in Arkansas

The Storm Prediction Center issued this mesoscale discussion at Apr 21, 2004, 6:29 PM CDT for 31 counties in Arkansas. It was in force for 91 min.

The area

The outline as issued.

The facts

Issued: Apr 21, 2004, 6:29 PM CDT (23:29 UTC)
Expired: Apr 21, 2004, 8:00 PM CDT
In force: 91 min
Issued by: the Storm Prediction Center

All 31 counties

Arkansas County, AR, Baxter County, AR, Benton County, AR, Boone County, AR, Carroll County, AR, Chicot County, AR, Clark County, AR, Cleburne County, AR, Fulton County, AR, Garland County, AR, Grant County, AR, Hempstead County, AR, Hot Spring County, AR, Howard County, AR, Independence County, AR, Izard County, AR, Little River County, AR, Madison County, AR, Marion County, AR, Miller County, AR, Montgomery County, AR, Nevada County, AR, Newton County, AR, Pike County, AR, Polk County, AR, Pulaski County, AR, Saline County, AR, Scott County, AR, Searcy County, AR, Sevier County, AR, Stone County, AR

The radar

The Little Rock radar (KLZK), 70 km from the middle of the area, began a volume at 23:32 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

Springfield, MO (KSGF), launched 12:00Z, 11.5 hours before the alert went out and 231 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: 297 J/kg
Mixed-layer CIN: -107 J/kg
Mixed-layer LCL: 855 m above ground
0-6 km bulk shear: 50 kt
0-1 km storm-relative helicity: 49 m²/s²
0-3 km storm-relative helicity: -7 m²/s²
Significant tornado parameter: 0.0
Supercell composite: 0.2

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.

Issued	Product	Office	Counties	Lasted
Apr 20, 7:22 PM CDT	Mesoscale Discussion	SPC	Benton, Madison, Washington	23 min
Apr 20, 7:50 PM CDT	Tornado Watch	SPC	Benton, Carroll, Crawford, Madison, Washington	5 hr
Apr 20, 8:57 PM CDT	Mesoscale Discussion	SPC	Benton, Carroll, Crawford, Madison, Washington	2 hr
Apr 20, 10:39 PM CDT	Mesoscale Discussion	SPC	Crawford, Franklin, Scott, Sebastian	3 hr
Apr 20, 10:57 PM CDT	Mesoscale Discussion	SPC	Benton, Carroll, Crawford, Madison, Washington	93 min
Apr 21, 2:13 PM CDT	Mesoscale Discussion	SPC	Baxter, Boone, Clark, Cleburne, Cleveland, Conway and 30 more	92 min
Apr 21, 2:40 PM CDT	Tornado Watch	SPC	Arkansas, Ashley, Baxter, Benton, Boone, Bradley and 52 more	6 hr
Apr 21, 4:40 PM CDT	Mesoscale Discussion	SPC	Arkansas, Ashley, Baxter, Benton, Boone, Bradley and 52 more	95 min

Nearby

Mesoscale Discussions in Arkansas, 2004 Every mesoscale discussion in 2004

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.