Alert archive / Louisiana / Mesoscale Discussions in 2011

Mesoscale Discussion 583

April 26, 20117 parishes in Louisiana; 5 counties in Texas

The Storm Prediction Center issued this mesoscale discussion at Apr 26, 2011, 1:34 AM CDT for 7 parishes in Louisiana; 5 counties in Texas. It was in force for 86 min.

The area

The outline as issued.

The facts

Issued: Apr 26, 2011, 1:34 AM CDT (06:34 UTC)
Expired: Apr 26, 2011, 3:00 AM CDT
In force: 86 min
Issued by: the Storm Prediction Center

Counties Allen Parish, LA, Beauregard Parish, LA, Calcasieu Parish, LA, Evangeline Parish, LA, Jefferson Davis Parish, LA, Rapides Parish, LA, Vernon Parish, LA, Hardin County, TX, Jasper County, TX, Newton County, TX, San Jacinto County, TX, Tyler County, TX

The radar

The Lake Charles radar (KLCH), 76 km from the middle of the area, began a volume at 06:35 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 212Apr 26, 1:55 AM CDT

The nearest sounding before it

Lake Charles Mun, LA (KLCH), launched 00:00Z, 6.6 hours before the alert went out and 77 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: 2759 J/kg
Mixed-layer CIN: 0 J/kg
Mixed-layer LCL: 581 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 86 m²/s²
0-3 km storm-relative helicity: 133 m²/s²
Significant tornado parameter: 1.5
Supercell composite: 8.4

Open this sounding in Storm Lab

The text

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

132 
ACUS11 KWNS 260634
SWOMCD
SPC MCD 260634 
LAZ000-TXZ000-260800-

MESOSCALE DISCUSSION 0583
NWS STORM PREDICTION CENTER NORMAN OK
0134 AM CDT TUE APR 26 2011

AREAS AFFECTED...SERN TX THROUGH SWRN LA

CONCERNING...SEVERE THUNDERSTORM WATCH 210...

VALID 260634Z - 260800Z

THE SEVERE WEATHER THREAT FOR SEVERE THUNDERSTORM WATCH 210
CONTINUES.

SEVERE STORMS EXPECTED TO PERSIST THROUGH SERN TX AND SWRN LA NEXT
FEW HOURS. MAIN THREAT APPEARS TO BE TRANSITIONING TO DAMAGING WIND
AND LARGE HAIL. STORM ON SWRN FLANK ARE NOT IN WW AND ACTIVITY MAY
ALSO CONTINUE ALL THE WAY TO THE COAST. CURRENT PLANS ARE TO REPLACE
TORNADO WATCH 210 WITH A SEVERE THUNDERSTORM WATCH SOON.

CLUSTER OF STORMS WITH EMBEDDED SUPERCELLS CONTINUE THROUGH SWRN LA
AND SERN TX AT 20-25 KT. RUC PFC DATA SHOW MODEST CAPPING INVERSION
AROUND 850 MB. THE ATMOSPHERE REMAINS MODERATELY UNSTABLE IN WARM
SECTOR SOUTH OF THE ACTIVITY. CONVERGENCE ALONG GUST FRONT AND 30-35
KT STORM RELATIVE INFLOW MAY SUSTAIN THE STORMS ALL THE WAY TO THE
COAST. SHEAR/INSTABILITY PARAMETER SPACE WILL SUPPORT EMBEDDED
SUPERCELL AND BOWING STRUCTURES AS ACTIVITY DEVELOPS SWD.

..DIAL.. 04/26/2011

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

ATTN...WFO...LCH...HGX...

LAT...LON   30669535 31059370 31379269 31089215 30529226 30219266
            30169355 30229465 30249527 30669535

SPC that day

Everything else SPC issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
Apr 25, 7:34 PM CDT	Mesoscale Discussion	SPC	Bossier, Claiborne, Lincoln, Union, Webster	116 min
Apr 25, 9:23 PM CDT	Tornado Watch	SPC	Caldwell, East Carroll, Franklin, Madison, Morehouse, Ouachita and 2 more	7 hr
Apr 25, 9:37 PM CDT	Mesoscale Discussion	SPC	De Soto, Sabine	83 min
Apr 25, 10:47 PM CDT	Tornado Watch	SPC	Allen, Beauregard, Evangeline, Rapides, Sabine, Vernon	5 hr
Apr 25, 11:05 PM CDT	Mesoscale Discussion	SPC	East Carroll, Morehouse, West Carroll	115 min
Apr 26, 1:52 AM CDT	Severe Thunderstorm Watch	SPC	Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 7 more	5 hr
Apr 26, 1:11 PM CDT	Mesoscale Discussion	SPC	Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 5 more	2 hr
Apr 26, 1:44 PM CDT	Tornado Watch PDS	SPC	Bossier, Caddo, Claiborne, Union, Webster	10 hr
Apr 26, 3:59 PM CDT	Mesoscale Discussion	SPC	Bossier, Caddo, Claiborne, Union, Webster	91 min
Apr 26, 4:56 PM CDT	Tornado Watch	SPC	Beauregard, Bienville, Caldwell, De Soto, Grant, Jackson and 9 more	5 hr
Apr 26, 6:43 PM CDT	Mesoscale Discussion	SPC	Beauregard, Bienville, Bossier, Caddo, Caldwell, Claiborne and 13 more	2 hr
Apr 26, 3:01 PM CDT	Mesoscale Discussion	SPC	Atascosa, Austin, Bastrop, Bee, Bexar, Blanco and 22 more	89 min
Apr 26, 3:15 PM CDT	Mesoscale Discussion	SPC	Archer, Baylor, Childress, Clay, Collingsworth, Cottle and 16 more	90 min
Apr 26, 3:43 PM CDT	Severe Thunderstorm Watch	SPC	Archer, Baylor, Clay, Foard, Hardeman, Knox and 2 more	6 hr

Nearby

Mesoscale Discussions in Louisiana, 2011 Mesoscale Discussions in Texas, 2011 Every 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.