Alert archive / Texas / Mesoscale Discussions in 2011
Mesoscale Discussion 581
The Storm Prediction Center issued this mesoscale discussion at Apr 25, 2011, 9:37 PM CDT for De Soto Parish, Sabine Parish, Louisiana; 32 counties in Texas. It was in force for 83 min.
The area
The outline as issued.
The facts
- Issued
- Apr 25, 2011, 9:37 PM CDT (02:37 UTC)
- Expired
- Apr 25, 2011, 11:00 PM CDT
- In force
- 83 min
- Issued by
- the Storm Prediction Center
All 34 counties
De Soto Parish, LA, Sabine Parish, LA, Anderson County, TX, Angelina County, TX, Cherokee County, TX, Ellis County, TX, Freestone County, TX, Gregg County, TX, Henderson County, TX, Hopkins County, TX, Houston County, TX, Jasper County, TX, Kaufman County, TX, Leon County, TX, Limestone County, TX, Madison County, TX, Nacogdoches County, TX, Navarro County, TX, Newton County, TX, Panola County, TX, Polk County, TX, Rains County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, San Jacinto County, TX, Shelby County, TX, Smith County, TX, Trinity County, TX, Tyler County, TX, Upshur County, TX, Van Zandt County, TX, Walker County, TX, Wood County, TX
The radar
The Shreveport radar (KSHV), 118 km from the middle of the area, began a volume at 02:38 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
Shreveport, LA (KSHV), launched 00:00Z, 2.6 hours before the alert went out and 127 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.
- Mixed-layer CAPE
- 782 J/kg
- Mixed-layer CIN
- -155 J/kg
- Mixed-layer LCL
- 1445 m above ground
- 0-6 km bulk shear
- 45 kt
- 0-1 km storm-relative helicity
- 262 m²/s²
- 0-3 km storm-relative helicity
- 553 m²/s²
- Significant tornado parameter
- 0.4
- Supercell composite
- 15.0
The text
As transmitted, in the capitals the NWS used until 2016.
388
ACUS11 KWNS 260238
SWOMCD
SPC MCD 260237
LAZ000-TXZ000-260400-
MESOSCALE DISCUSSION 0581
NWS STORM PREDICTION CENTER NORMAN OK
0937 PM CDT MON APR 25 2011
AREAS AFFECTED...N-CENTRAL THROUGH E TX...WRN LA.
CONCERNING...TORNADO WATCH 204...205...
VALID 260237Z - 260400Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 204...205...CONTINUES.
CLUSTER OF STG-SVR TSTMS...WITH EMBEDDED SUPERCELLS BEARING
TORNADO/HAIL/WIND DAMAGE RISK...CONTINUES TO MOVE ESEWD ACROSS
E-CENTRAL TX TOWARD LFK AREA. ACTIVITY WILL BE IN SOME COUNTIES OF
WW 204 AFTER SCHEDULED 03Z EXPIRATION...AND STILL MAY BE UNDERWAY
NEAR 04Z EXPIRATION OF WW 205. THEREFORE EITHER WW MAY BE EXTENDED
IN TIME FOR AREAS STILL TO BE AFFECTED BY THIS ACTIVITY.
CONVECTIVE/INSTABILITY TRENDS WILL BE MONITORED FOR POSSIBILITY OF
ADDITIONAL WW OVER SE TX AND ADJACENT PORTIONS LA.
ENVIRONMENTAL MLCINH IS INCREASING WITHIN 50-75 NM AHEAD OF THESE
TSTMS...BASED ON MODIFIED LCH/SHV RAOBS AND RUC SOUNDINGS.
HOWEVER...UPDRAFT ENHANCEMENTS DUE TO INTERNAL DYNAMICS OF THESE
TSTMS MAY OVERCOME SUBCLOUD STABILIZATION...AND FORCE LIFTED PARCELS
TO REMAIN ROOTED NEAR SFC. IF THIS KEEPS OCCURRING UNTIL ACTIVITY
REACHES CONSIDERABLY MORE MOIST AIR MASS OVER PORTIONS SE TX AND
SWRN/W-CENTRAL LA...COMPLEX MAY PERSIST FOR SEVERAL MORE HOURS.
OVER SABINE RIVER REGION...SFC COOLING WILL BE MORE GRADUAL GIVEN
DEW POINTS NEAR 70 F...WITH MLCINH UNDER 50 J/KG. VERTICAL WIND
PROFILES WILL REMAIN FAVORABLE WITH 45-50 KT EFFECTIVE SHEAR
MAGNITUDES. BLEND OF POE VWP...LDB PROFILER AND RUC FCST WINDS
SUGGESTS LLJ ENHANCEMENT WILL LEAD TO 0-1 KM SRH 300-400 J/KG FOR
ANY CONVECTION THAT CAN PERSIST INTO JAS/POE REGION. TSTM
DEVELOPMENT STILL IS POSSIBLE ALONG DRYLINE NEAR I-35...AND COLD
FRONT INTERACTING WITH IT FROM N-S...HOWEVER STRENGTHENING MLCINH
APPEARS TO BE REDUCING PROBABILITY OF SUCH ADDITIONAL DEVELOPMENT
WITH TIME.
..EDWARDS.. 04/26/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...LCH...SHV...HGX...FWD...
LAT...LON 32109336 31829317 30829335 30539487 30639603 31599719
32649667 33339564 32789501 32109336SPC 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, 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, 1:34 AM CDT | Mesoscale Discussion | SPC | Allen, Beauregard, Calcasieu, Evangeline, Jefferson Davis, Rapides and 1 more | 86 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 | 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 Texas, 2011Mesoscale Discussions in Louisiana, 2011Every 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.