Alert archive / Louisiana / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 688
The Storm Prediction Center issued this severe thunderstorm watch at Dec 20, 2012, 1:07 AM CST for 5 states. It was in force for 5 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 20, 2012, 1:07 AM CST (07:07 UTC)
- Expired
- Dec 20, 2012, 6:28 AM CST
- In force
- 5 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 1 in
- Strongest gust expected
- 65 kt
All 85 counties
Arkansas County, AR, Ashley County, AR, Bradley County, AR, Calhoun County, AR, Chicot County, AR, Cleveland County, AR, Crittenden County, AR, Cross County, AR, Dallas County, AR, Desha County, AR, Drew County, AR, Grant County, AR, Jefferson County, AR, Lee County, AR, Lincoln County, AR, Lonoke County, AR, Monroe County, AR, Ouachita County, AR, Phillips County, AR, Prairie County, AR, St. Francis County, AR, Union County, AR, White County, AR, Woodruff County, AR, Avoyelles Parish, LA, Bienville Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, Franklin Parish, LA, Grant Parish, LA, Jackson Parish, LA, LaSalle Parish, LA, Lincoln Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Natchitoches Parish, LA, Ouachita Parish, LA, Rapides Parish, LA, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, Vernon Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Adams County, MS, Benton County, MS, Bolivar County, MS, Carroll County, MS, Claiborne County, MS, Coahoma County, MS, DeSoto County, MS, Grenada County, MS, Holmes County, MS, Humphreys County, MS, Issaquena County, MS, Jefferson County, MS, Lafayette County, MS, Leflore County, MS, Marshall County, MS, Panola County, MS, Quitman County, MS, Sharkey County, MS, Sunflower County, MS, Tallahatchie County, MS, Tate County, MS, Tunica County, MS, Warren County, MS, Washington County, MS, Yalobusha County, MS, Yazoo County, MS, Fayette County, TN, Hardeman County, TN, Shelby County, TN, Angelina County, TX, Jasper County, TX, Newton County, TX, Sabine County, TX, San Augustine County, TX, Tyler County, TX
The radar
The Shreveport radar (KSHV), 135 km from the middle of the area, began a volume at 07:09 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
- 20%
- One or more EF2 to EF5 tornadoes
- 10%
- Ten or more severe wind reports
- 50%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 5%
- One or more hailstones of 2 inches or more
- 5%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 20, 1:12 AM CST | Severe Thunderstorm Warning | SHV | Columbia, Union | 63 min |
| Dec 20, 1:37 AM CST | Severe Thunderstorm Warning | LZK | Arkansas, Grant, Jefferson, Lonoke | 38 min |
| Dec 20, 1:51 AM CST | Severe Thunderstorm Warning | SHV | Bienville, De Soto, Grant, Jackson, Natchitoches, Red River and 2 more | 54 min |
| Dec 20, 2:04 AM CST | Severe Thunderstorm Warning | JAN | Ashley | 71 min |
| Dec 20, 2:04 AM CST | Severe Thunderstorm Warning | SHV | Union | 56 min |
| Dec 20, 2:11 AM CST | Severe Thunderstorm Warning | LZK | Arkansas, Desha, Jefferson, Lincoln, Monroe | 49 min |
| Dec 20, 2:39 AM CST | Tornado Warning | LZK | Arkansas, Monroe | 36 min |
| Dec 20, 2:44 AM CST | Severe Thunderstorm Warning | SHV | Caldwell, Grant, Jackson, LaSalle, Natchitoches, Winn | 61 min |
| Dec 20, 2:59 AM CST | Severe Thunderstorm Warning | JAN | Chicot | 76 min |
| Dec 20, 3:10 AM CST | Severe Thunderstorm Warning | JAN | East Carroll, Franklin, Morehouse, Richland, West Carroll | 50 min |
| Dec 20, 3:42 AM CST | Severe Thunderstorm Warning | JAN | East Carroll, Madison | 78 min |
| Dec 20, 3:45 AM CST | Severe Thunderstorm Warning | JAN | Humphreys, Leflore, Sunflower | 45 min |
| Dec 20, 3:49 AM CST | Severe Thunderstorm Warning | MEG | Crittenden | 41 min |
| Dec 20, 3:54 AM CST | Severe Thunderstorm Warning | JAN | Catahoula, Concordia, Tensas | 66 min |
| Dec 20, 4:03 AM CST | Severe Thunderstorm Warning | MEG | DeSoto, Marshall | 42 min |
| Dec 20, 4:18 AM CST | Severe Thunderstorm Warning | JAN | Holmes, Yazoo | 72 min |
| Dec 20, 4:25 AM CST | Severe Thunderstorm Warning | JAN | Carroll, Grenada, Leflore, Montgomery | 80 min |
| Dec 20, 4:34 AM CST | Severe Thunderstorm Warning | JAN | Adams, Claiborne, Franklin, Jefferson | 71 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, 7.1 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
- 237 J/kg
- Mixed-layer CIN
- -56 J/kg
- Mixed-layer LCL
- 943 m above ground
- 0-6 km bulk shear
- 55 kt
- 0-1 km storm-relative helicity
- 385 m²/s²
- 0-3 km storm-relative helicity
- 445 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 1.5
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 19, 7:07 PM CST | Mesoscale Discussion | SPC | Baxter, Benton, Boone, Carroll, Conway, Crawford and 24 more | 53 min |
| Dec 19, 7:36 PM CST | Tornado Watch | SPC | Baxter, Benton, Boone, Carroll, Clark, Cleburne and 36 more | 6 hr |
| Dec 19, 10:22 PM CST | Mesoscale Discussion | SPC | Baxter, Boone, Carroll, Clark, Cleburne, Conway and 29 more | 83 min |
| Dec 19, 11:55 PM CST | Mesoscale Discussion | SPC | Ashley, Chicot | 95 min |
| Dec 20, 12:50 AM CST | Mesoscale Discussion | SPC | Arkansas, Ashley, Bradley, Calhoun, Chicot, Cleveland and 23 more | 55 min |
| Dec 20, 4:08 AM CST | Mesoscale Discussion | SPC | Chicot, Crittenden | 67 min |
| Dec 19, 9:56 PM CST | Severe Thunderstorm Watch | SPC | Bossier, Caddo, De Soto | 5 hr |
| Dec 20, 4:23 AM CST | Tornado Watch | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Livingston and 9 more | 9 hr |
| Dec 20, 7:09 AM CST | Mesoscale Discussion | SPC | Saint James, Saint John the Baptist, Saint Tammany, Tangipahoa, Washington | 96 min |
| Dec 20, 9:56 AM CST | Mesoscale Discussion | SPC | Ascension, East Baton Rouge, East Feliciana, Iberville, Livingston, Saint Helena and 6 more | 64 min |
| Dec 19, 9:00 PM CST | Mesoscale Discussion | SPC | Anderson, Camp, Cherokee, Dallas, Ellis, Falls and 19 more | 2 hr |
Nearby
Severe Thunderstorm Watches in Louisiana, 2012Severe Thunderstorm Watches in Mississippi, 2012Severe Thunderstorm Watches in Arkansas, 2012Every severe thunderstorm watch in 2012
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.