Alert archive / Louisiana / Mesoscale Discussions in 2011
Mesoscale Discussion 972
The Storm Prediction Center issued this mesoscale discussion at May 25, 2011, 7:45 PM CDT for 15 parishes in Louisiana; 4 counties in Texas. It was in force for 60 min.
The area
The outline as issued.
The facts
- Issued
- May 25, 2011, 7:45 PM CDT (00:45 UTC)
- Expired
- May 25, 2011, 8:45 PM CDT
- In force
- 60 min
- Issued by
- the Storm Prediction Center
Counties Bienville Parish, LA, Caldwell Parish, LA, De Soto Parish, LA, Grant Parish, LA, Jackson 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, West Carroll Parish, LA, Winn Parish, LA, Angelina County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX
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, 0.8 hours before the alert went out and 96 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
- 1872 J/kg
- Mixed-layer CIN
- -61 J/kg
- Mixed-layer LCL
- 1613 m above ground
- 0-6 km bulk shear
- 49 kt
- 0-1 km storm-relative helicity
- 131 m²/s²
- 0-3 km storm-relative helicity
- 182 m²/s²
- Significant tornado parameter
- 0.5
- Supercell composite
- 10.7
The text
As transmitted, in the capitals the NWS used until 2016.
041
ACUS11 KWNS 260046
SWOMCD
SPC MCD 260045
LAZ000-TXZ000-260145-
MESOSCALE DISCUSSION 0972
NWS STORM PREDICTION CENTER NORMAN OK
0745 PM CDT WED MAY 25 2011
AREAS AFFECTED...E CNTRL TX...NRN LA...SRN AR
CONCERNING...TORNADO WATCH 374...
VALID 260045Z - 260145Z
THE SEVERE WEATHER THREAT FOR TORNADO WATCH 374 CONTINUES.
ONGOING SUPERCELLS ACROSS THE WW AREA WILL REMAIN CAPABLE OF
PRODUCING LARGE HAIL...DMGG WINDS...AND TORNADOES.
DEEP LAYER WINDS HAVE PRIMARILY BECOME UNIDIRECTIONAL WITH THE SRN
EXTENT OF THE WATCH...WITH STRAIGHT-LINE HODOGRAPHS SUPPORTING
SPLITTING SUPERCELLS. SURFACE CONVERGENCE REMAINS SOMEWHAT WEAKER
ACROSS THE SRN EXTENT OF THE WATCH...BUT APPEARS TO BE SUFFICIENT
FOR THE MAINTENANCE OF CONVECTION...PRIMARILY IN ASSOCIATION WITH A
NEARLY STATIONARY FRONT EXTENDING THROUGH ERN AR AND SWWD THROUGH
NWRN LA AND INTO CNTRL TX. STEEP LAPSE RATE ENVIRONMENT REPRESENTED
ON THE 00Z SHV SOUNDING WITH MID LEVEL LAPSE RATES IN EXCESS OF 6.5
C/KM AND VERY UNSTABLE AIR MASS WILL CONTINUE TO SUPPORT RAPID
DEVELOPMENT...WITH LARGE HAIL...DMGG WINDS...AND TORNADOES ALL
POSSIBLE.
..HURLBUT.. 05/26/2011
...PLEASE SEE WWW.SPC.NOAA.GOV FOR GRAPHIC PRODUCT...
ATTN...WFO...JAN...LCH...SHV...
LAT...LON 31199316 31249479 31709442 32349342 32819267 32989188
32939130 32239180 31689224 31199316SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 25, 7:22 PM CDT | Mesoscale Discussion | SPC | Union | 53 min |
| May 25, 9:43 PM CDT | Tornado Watch | SPC | Avoyelles, Caldwell, Catahoula, Concordia, East Carroll, Franklin and 14 more | 5 hr |
| May 26, 2:05 AM CDT | Mesoscale Discussion | SPC | Ascension, East Baton Rouge, East Feliciana, Iberville, Livingston, Orleans and 10 more | 85 min |
| May 26, 5:18 PM CDT | Mesoscale Discussion | SPC | Orleans, Saint Bernard, Saint Tammany | 57 min |
| May 26, 2:01 AM CDT | Severe Thunderstorm Watch | SPC | Calhoun, DeWitt, Goliad, Jackson, Lavaca, Matagorda and 3 more | 4 hr |
Nearby
Mesoscale Discussions in Louisiana, 2011Mesoscale Discussions in Texas, 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.