Alert archive / Louisiana / Severe Thunderstorm Watches in 2009
Severe Thunderstorm Watch 754
The Storm Prediction Center issued this severe thunderstorm watch at Oct 1, 2009, 10:24 PM CDT for Ashley County, Chicot County, Arkansas; 17 parishes in Louisiana; 7 counties in Mississippi. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Oct 1, 2009, 10:24 PM CDT (03:24 UTC)
- Expired
- Oct 2, 2009, 3:08 AM CDT
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 60 kt
All 26 counties
Ashley County, AR, Chicot County, AR, Caldwell Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Franklin County, MS, Issaquena County, MS, Jefferson County, MS, Sharkey County, MS, Warren County, MS, Washington County, MS
The radar
The Shreveport radar (KSHV), 154 km from the middle of the area, began a volume at 03:27 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.
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 10%
- One or more EF2 to EF5 tornadoes
- 5%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 20%
- Ten or more severe hail reports
- 20%
- One or more hailstones of 2 inches or more
- 10%
- Six or more combined severe hail and wind reports
- 60%
Warnings issued inside it
4 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 1, 10:44 PM CDT | Severe Thunderstorm Warning | JAN | Chicot | 54 min |
| Oct 1, 11:23 PM CDT | Tornado Warning | SHV | Bienville, Natchitoches, Red River, Winn | 29 min |
| Oct 2, 1:00 AM CDT | Severe Thunderstorm Warning | JAN | Catahoula, Concordia, Franklin, Tensas | 75 min |
| Oct 2, 1:45 AM CDT | Severe Thunderstorm Warning | JAN | Adams | 57 min |
Discussions around it
SPC mesoscale discussions over the same counties from four hours before the watch to its end.
The nearest sounding before it
Shreveport, LA (KSHV), launched 00:00Z, 3.4 hours before the alert went out and 145 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
- 2755 J/kg
- Mixed-layer CIN
- -8 J/kg
- Mixed-layer LCL
- 934 m above ground
- 0-6 km bulk shear
- 44 kt
- 0-1 km storm-relative helicity
- 185 m²/s²
- 0-3 km storm-relative helicity
- 258 m²/s²
- Significant tornado parameter
- 3.8
- Supercell composite
- 15.0
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Oct 1, 8:37 PM CDT | Mesoscale Discussion | SPC | Ashley, Bradley, Calhoun, Clark, Cleveland, Columbia and 14 more | 83 min |
| Oct 1, 9:28 PM CDT | Mesoscale Discussion | SPC | Ashley, Chicot, Desha, Drew, Lincoln | 92 min |
| Oct 1, 11:45 PM CDT | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Concordia and 8 more | 90 min |
| Oct 2, 1:07 AM CDT | Tornado Watch | SPC | Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 21 more | 5 hr |
| Oct 2, 3:11 AM CDT | Mesoscale Discussion | SPC | Acadia, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge and 13 more | 94 min |
Nearby
Severe Thunderstorm Watches in Louisiana, 2009Severe Thunderstorm Watches in Mississippi, 2009Severe Thunderstorm Watches in Arkansas, 2009Every severe thunderstorm watch 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; radar from the NEXRAD Level II archive.