Alert archive / Louisiana / Mesoscale Discussions in 2017
Mesoscale Discussion 906
The Storm Prediction Center issued this mesoscale discussion at May 28, 2017, 5:01 PM CDT for 15 parishes in Louisiana; 7 counties in Texas. It was in force for 59 min.
The area
The outline as issued.
The facts
- Issued
- May 28, 2017, 5:01 PM CDT (22:01 UTC)
- Expired
- May 28, 2017, 6:00 PM CDT
- In force
- 59 min
- Issued by
- the Storm Prediction Center
- Chance of a watch
- 80%
All 22 counties
Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Claiborne Parish, LA, De Soto Parish, LA, Jackson Parish, LA, Lincoln Parish, LA, Morehouse Parish, LA, Ouachita Parish, LA, Red River Parish, LA, Richland Parish, LA, Union Parish, LA, Webster Parish, LA, Winn Parish, LA, Gregg County, TX, Harrison County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Shelby County, TX
The radar
The Shreveport radar (KSHV), 44 km from the middle of the area, began a volume at 22:01 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 (KBAD), launched 12:00Z, 10.0 hours before the alert went out and 35 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
- 0 J/kg
- Mixed-layer CIN
- No buoyant parcel
- Mixed-layer LCL
- 1753 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- -304 m²/s²
- 0-3 km storm-relative helicity
- -56 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.6
The text
As transmitted.
294 ACUS11 KWNS 282201 SWOMCD SPC MCD 282201 LAZ000-TXZ000-282300- Mesoscale Discussion 0906 NWS Storm Prediction Center Norman OK 0501 PM CDT Sun May 28 2017 Areas affected...Northeast TX...Northern LA Concerning...Severe potential...Watch likely Valid 282201Z - 282300Z Probability of Watch Issuance...80 percent SUMMARY...Strong thunderstorms will spread across northeast TX into northern LA this evening. Scattered storms will likely attain severe levels with damaging winds and large hail the expected threats. DISCUSSION...A narrow corridor of strong boundary-layer heating has contributed to an axis of strong instability across east TX into extreme western LA. Surface-3km lapse rates are now on the order of 7 C/km reflective of afternoon temperatures in the mid 80s. Over the last hour or so an upward evolving complex of storms has slowly matured over northeast TX. This activity should spread/develop eastward along an ill-defined outflow boundary draped across northern LA. Damaging winds and large hail can be expected with this convection. ..Darrow/Guyer.. 05/28/2017 ...Please see www.spc.noaa.gov for graphic product... ATTN...WFO...JAN...SHV... LAT...LON 32939482 32999221 32679143 31879191 31579505 32939482
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 28, 2:53 AM CDT | Mesoscale Discussion | SPC | Bossier, Caddo, Claiborne, Lincoln, Union, Webster | 2 hr |
| May 28, 10:59 AM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Calcasieu, Cameron, Iberia, Iberville and 15 more | 2 hr |
| May 28, 5:19 PM CDT | Severe Thunderstorm Watch | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more | 4 hr |
| May 27, 7:12 PM CDT | Mesoscale Discussion | SPC | Dallam, Hansford, Hartley, Ochiltree, Sherman | 2 hr |
| May 27, 9:07 PM CDT | Mesoscale Discussion | SPC | Hansford, Hemphill, Hutchinson, Lipscomb, Ochiltree, Roberts and 1 more | 53 min |
| May 27, 11:47 PM CDT | Mesoscale Discussion | SPC | Clay, Cooke, Fannin, Grayson, Lamar, Montague and 1 more | 58 min |
| May 28, 12:06 AM CDT | Severe Thunderstorm Watch | SPC | Bowie, Collin, Cooke, Denton, Fannin, Grayson and 4 more | 5 hr |
| May 28, 4:59 AM CDT | Mesoscale Discussion | SPC | Bowie, Camp, Cass, Collin, Delta, Denton and 7 more | 2 hr |
| May 28, 1:34 PM CDT | Mesoscale Discussion | SPC | Bastrop, Bell, Bexar, Blanco, Burnet, Caldwell and 18 more | 56 min |
| May 28, 3:09 PM CDT | Severe Thunderstorm Watch | SPC | Anderson, Atascosa, Austin, Bandera, Bastrop, Bell and 58 more | 8 hr |
| May 28, 6:03 PM CDT | Mesoscale Discussion | SPC | Anderson, Bandera, Bastrop, Bell, Bexar, Blanco and 40 more | 57 min |
Nearby
Mesoscale Discussions in Louisiana, 2017Mesoscale Discussions in Texas, 2017Every mesoscale discussion in 2017
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.