Alert archive / Louisiana / Mesoscale Discussions in 2009
Mesoscale Discussion 795
The Storm Prediction Center issued this mesoscale discussion at May 11, 2009, 2:20 PM CDT for 19 parishes in Louisiana; 17 counties in Mississippi. It was in force for 55 min.
The area
The outline as issued.
The facts
- Issued
- May 11, 2009, 2:20 PM CDT (19:20 UTC)
- Expired
- May 11, 2009, 3:15 PM CDT
- In force
- 55 min
- Issued by
- the Storm Prediction Center
All 36 counties
Allen Parish, LA, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Grant Parish, LA, LaSalle Parish, LA, Livingston Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Helena Parish, LA, Saint Landry Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Hancock County, MS, Jefferson County, MS, Lamar County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Stone County, MS, Walthall County, MS, Wilkinson County, MS
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 12:00Z, 7.3 hours before the alert went out and 188 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
- 339 J/kg
- Mixed-layer CIN
- -90 J/kg
- Mixed-layer LCL
- 611 m above ground
- 0-6 km bulk shear
- 30 kt
- 0-1 km storm-relative helicity
- 57 m²/s²
- 0-3 km storm-relative helicity
- 106 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 0.0
The text
As transmitted, in the capitals the NWS used until 2016.
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</html>SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 10, 7:29 PM CDT | Mesoscale Discussion | SPC | Concordia, Grant | 61 min |
| May 10, 7:50 PM CDT | Severe Thunderstorm Watch | SPC | Catahoula, Concordia, Tensas | 5 hr |
| May 11, 1:05 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 11 more | 85 min |
| May 11, 2:52 PM CDT | Severe Thunderstorm Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 21 more | 5 hr |
| May 11, 6:15 PM CDT | Mesoscale Discussion | SPC | Ascension, Assumption, Iberville, Livingston, Saint Charles, Saint James and 2 more | 90 min |
Nearby
Mesoscale Discussions in Louisiana, 2009Mesoscale Discussions in Mississippi, 2009Every mesoscale discussion in 2009
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.