Alert archive / Louisiana / Mesoscale Discussions in 2005

Mesoscale Discussion 331

March 21, 200516 counties in Arkansas; 20 parishes in Louisiana

The Storm Prediction Center issued this mesoscale discussion at Mar 21, 2005, 11:26 PM CST for 16 counties in Arkansas; 20 parishes in Louisiana. It was in force for 94 min.

The area

The outline as issued.

The facts

Issued: Mar 21, 2005, 11:26 PM CST (05:26 UTC)
Expired: Mar 22, 2005, 1:00 AM CST
In force: 94 min
Issued by: the Storm Prediction Center

All 36 counties

Arkansas County, AR, 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, Bienville Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA

The radar

The Shreveport radar (KSHV), 158 km from the middle of the area, began a volume at 05:26 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 00:00Z, 5.4 hours before the alert went out and 197 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: 18 J/kg
Mixed-layer CIN: -88 J/kg
Mixed-layer LCL: 1125 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 31 m²/s²
0-3 km storm-relative helicity: 140 m²/s²
Significant tornado parameter: -0.0
Supercell composite: -0.0

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

000
ACUS11 KWNS 220526
SWOMCD
SPC MCD 220526 
MSZ000-ARZ000-LAZ000-TXZ000-220700-

MESOSCALE DISCUSSION 0331
NWS STORM PREDICTION CENTER NORMAN OK
1126 PM CST MON MAR 21 2005

AREAS AFFECTED...SRN AR AND NRN LA

CONCERNING...TORNADO WATCH 58...

VALID 220526Z - 220700Z

CLUSTER OF VIGOROUS STORMS CONTINUES ACROSS MOST OF THE WRN HALF OF
TORNADO WATCH 58 LATE TONIGHT. TORNADOES...LARGE HAIL...AND ISOLATED
DAMAGING WINDS REMAIN POSSIBLE WITHIN THE WATCH AREA.

LATEST DATA SUGGESTS THAT CONVECTION IS CONTINUING TO FORM WITHIN
WARM CONVEYOR BELT OF DEEP LAYER CYCLONE CENTERED ACROSS NWRN OK.
AIR MASS STREAMING ACROSS THE WARM FRONT...WHILE ONLY MARGINALLY
UNSTABLE...IS SUFFICIENT TO MAINTAIN POTENT STORM UPDRAFTS WITHIN
STRONGLY SHEARED ENVIRONMENT. WITH VERY STRONG DYNAMIC FORCING
EXPECTED TO CONTINUE TO BE FOCUSED ACROSS THE ARKLATEX THROUGH THE
NIGHT...SEVERE STORM POTENTIAL WILL CONTINUE AS WELL. RECENTLY...AN
INTENSE SUPERCELL WITH LONG-LIVED AND STRONG ROTATION MOVED FROM
BIENVILLE TO JACKSON AND LINCOLN PARISHES IN NCNTRL LA. ADDITIONAL
STORMS...WEST OF THIS ACTIVITY...SHOULD CONTINUE TO MOVE ACROSS THE
WATCH IN THE NEXT FEW HOURS.

..CARBIN.. 03/22/2005

...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...

ATTN...WFO...MEG...JAN...LZK...LCH...SHV...

31329160 31329372 34439299 34419088

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Mar 21, 8:29 PM CST	Mesoscale Discussion	SPC	Bradley, Calhoun, Clark, Cleveland, Columbia, Dallas and 11 more	91 min
Mar 21, 9:20 PM CST	Tornado Watch	SPC	Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 11 more	7 hr
Mar 21, 10:12 PM CST	Mesoscale Discussion	SPC	Benton, Boone, Carroll, Crawford, Franklin, Johnson and 8 more	63 min
Mar 21, 10:15 PM CST	Severe Thunderstorm Watch	SPC	Benton, Carroll, Crawford, Franklin, Logan, Madison and 5 more	6 hr
Mar 21, 11:09 PM CST	Mesoscale Discussion	SPC	Hempstead, Howard, Lafayette, Little River, Miller, Pike and 1 more	96 min
Mar 22, 1:45 AM CST	Tornado Watch	SPC	Ashley, Bradley, Chicot, Union	6 hr
Mar 22, 2:20 AM CST	Mesoscale Discussion	SPC	Benton, Carroll, Crawford, Franklin, Logan, Madison and 5 more	85 min
Mar 22, 3:57 AM CST	Mesoscale Discussion	SPC	Ashley, Bradley, Chicot, Union	2 hr
Mar 22, 11:55 AM CST	Mesoscale Discussion	SPC	Arkansas, Chicot, Cleburne, Conway, Crittenden, Cross and 20 more	95 min
Mar 22, 12:55 PM CST	Severe Thunderstorm Watch	SPC	Arkansas, Baxter, Boone, Chicot, Clay, Cleburne and 29 more	7 hr
Mar 22, 2:39 PM CST	Mesoscale Discussion	SPC	Baxter, Cleburne, Craighead, Crittenden, Cross, Faulkner and 19 more	96 min
Mar 22, 4:27 PM CST	Mesoscale Discussion	SPC	Clay, Mississippi	33 min
Mar 22, 12:50 AM CST	Tornado Watch	SPC	De Soto, Sabine	5 hr
Mar 22, 3:00 AM CST	Tornado Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 13 more	5 hr
Mar 22, 3:43 AM CST	Mesoscale Discussion	SPC	De Soto, Sabine	2 hr
Mar 22, 5:59 AM CST	Mesoscale Discussion	SPC	Acadia, Allen, Avoyelles, Calcasieu, Cameron, East Baton Rouge and 14 more	2 hr
Mar 22, 6:55 AM CST	Tornado Watch	SPC	Saint Tammany, Washington	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2005 Mesoscale Discussions in Arkansas, 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.