Alert archive / Louisiana / Severe Thunderstorm Watches in 2012
Severe Thunderstorm Watch 693
The Storm Prediction Center issued this severe thunderstorm watch at Dec 25, 2012, 9:02 AM CST for Ashley County, Chicot County, Union County, Arkansas; 26 parishes in Louisiana; 12 counties in Texas. It was in force for 7 hr.
The area
The outline as issued.
The facts
- Issued
- Dec 25, 2012, 9:02 AM CST (15:02 UTC)
- Expired
- Dec 25, 2012, 4:00 PM CST
- In force
- 7 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2 in
- Strongest gust expected
- 60 kt
All 41 counties
Ashley County, AR, Chicot County, AR, Union County, AR, Bienville Parish, LA, Bossier Parish, LA, Caddo Parish, LA, Caldwell Parish, LA, Catahoula Parish, LA, Claiborne Parish, LA, Concordia Parish, LA, De Soto 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, Red River Parish, LA, Richland Parish, LA, Sabine Parish, LA, Tensas Parish, LA, Union Parish, LA, Webster Parish, LA, West Carroll Parish, LA, Winn Parish, LA, Angelina County, TX, Cherokee County, TX, Gregg County, TX, Harrison County, TX, Marion County, TX, Nacogdoches County, TX, Panola County, TX, Rusk County, TX, Sabine County, TX, San Augustine County, TX, Shelby County, TX, Smith County, TX
The radar
The Shreveport radar (KSHV), 26 km from the middle of the area, began a volume at 15:05 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
- 30%
- One or more gusts of 65 knots or more
- 30%
- Ten or more severe hail reports
- 30%
- One or more hailstones of 2 inches or more
- 20%
- Six or more combined severe hail and wind reports
- 80%
Warnings issued inside it
12 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 25, 9:42 AM CST | Tornado Warning | SHV | Angelina, Cherokee | 18 min |
| Dec 25, 10:12 AM CST | Severe Thunderstorm Warning | SHV | Angelina, Nacogdoches | 33 min |
| Dec 25, 10:37 AM CST | Severe Thunderstorm Warning | SHV | Angelina, Nacogdoches, San Augustine, Shelby | 38 min |
| Dec 25, 11:00 AM CST | Severe Thunderstorm Warning | SHV | Sabine | 45 min |
| Dec 25, 11:22 AM CST | Severe Thunderstorm Warning | SHV | Natchitoches, Red River | 53 min |
| Dec 25, 11:50 AM CST | Flash Flood Warning | JAN | Catahoula, Concordia, Franklin, Madison, Tensas | 4 hr |
| Dec 25, 12:02 PM CST | Severe Thunderstorm Warning | SHV | Bienville, Grant, Jackson, Natchitoches, Winn | 58 min |
| Dec 25, 12:37 PM CST | Severe Thunderstorm Warning | SHV | Caldwell, Grant, LaSalle, Ouachita, Winn | 53 min |
| Dec 25, 1:04 PM CST | Severe Thunderstorm Warning | JAN | Catahoula, Concordia | 56 min |
| Dec 25, 1:09 PM CST | Tornado Warning | JAN | Catahoula, Concordia | 20 min |
| Dec 25, 1:37 PM CST | Severe Thunderstorm Warning | JAN | Catahoula, Concordia | 38 min |
| Dec 25, 1:49 PM CST | Severe Thunderstorm Warning | JAN | Tensas | 41 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
Lake Charles Mun, LA (KLCH), launched 12:00Z, 3.0 hours before the alert went out and 246 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
- 1505 J/kg
- Mixed-layer CIN
- -9 J/kg
- Mixed-layer LCL
- 500 m above ground
- 0-6 km bulk shear
- 54 kt
- 0-1 km storm-relative helicity
- 265 m²/s²
- 0-3 km storm-relative helicity
- 353 m²/s²
- Significant tornado parameter
- 0.0
- Supercell composite
- 10.9
The text
As transmitted, in the capitals the NWS used until 2016.
054
WWUS20 KWNS 251459
SEL3
SPC WW 251459
ARZ000-LAZ000-MSZ000-TXZ000-252200-
URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 693
NWS STORM PREDICTION CENTER NORMAN OK
855 AM CST TUE DEC 25 2012
THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF
EXTREME SOUTHERN ARKANSAS
NORTHERN LOUISIANA
EXTREME WESTERN MISSISSIPPI
NORTHEAST TEXAS
EFFECTIVE THIS TUESDAY MORNING AND AFTERNOON FROM 855 AM UNTIL
400 PM CST.
HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.
THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 60
STATUTE MILES NORTH AND SOUTH OF A LINE FROM 50 MILES SOUTHWEST
OF LONGVIEW TEXAS TO 55 MILES EAST OF MONROE LOUISIANA. FOR A
COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE
UPDATE (WOUS64 KWNS WOU3).
REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.
OTHER WATCH INFORMATION...CONTINUE...WW 691...WW 692...
DISCUSSION...SVR TSTMS WITH HAIL AND ISOLATED GUSTS SHOULD INCREASE
IN COVERAGE AND SHIFT ENEWD ACROSS WW AREA THROUGH AFTN...N OF SFC
WARM FRONT OVER SE TX AND SRN LA. 40-50 KT EFFECTIVE SHEAR
MAGNITUDES AND ELEVATED MUCAPE UP TO 1000 J/KG WILL SUPPORT TSTM
ORGANIZATION.
AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT
TO 2 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60
KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 450. MEAN STORM
MOTION VECTOR 24040.
...EDWARDSSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Dec 25, 12:11 PM CST | Mesoscale Discussion | SPC | Cleburne, Conway, Crawford, Faulkner, Franklin, Garland and 20 more | 5 hr |
| Dec 25, 12:23 PM CST | Mesoscale Discussion | SPC | Ashley, Chicot | 67 min |
| Dec 25, 1:00 PM CST | Mesoscale Discussion | SPC | Columbia, Hempstead, Lafayette, Little River, Miller, Nevada | 5 hr |
| Dec 25, 2:14 PM CST | Mesoscale Discussion | SPC | Baxter, Boone, Carroll, Clay, Craighead, Cross and 10 more | 4 hr |
| Dec 25, 3:22 PM CST | Mesoscale Discussion | SPC | Chicot | 53 min |
| Dec 25, 1:01 AM CST | Mesoscale Discussion | SPC | Allen, Beauregard, Sabine, Vernon | 59 min |
| Dec 25, 1:37 AM CST | Severe Thunderstorm Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, De Soto and 9 more | 7 hr |
| Dec 25, 5:56 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, De Soto and 10 more | 94 min |
| Dec 25, 7:00 AM CST | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Assumption, Beauregard, Calcasieu and 24 more | 60 min |
| Dec 25, 7:28 AM CST | Tornado Watch | SPC | Acadia, Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia and 19 more | 6 hr |
| Dec 25, 8:46 AM CST | Mesoscale Discussion | SPC | Allen, Avoyelles, Beauregard, Bienville, Calcasieu, Caldwell and 21 more | 59 min |
| Dec 25, 9:17 AM CST | Tornado Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 10 more | 8 hr |
| Dec 25, 12:19 PM CST | Mesoscale Discussion | SPC | Acadia, Allen, Ascension, Assumption, Avoyelles, Beauregard and 35 more | 71 min |
| Dec 25, 12:58 PM CST | Tornado Watch | SPC | Ascension, Assumption, Catahoula, Concordia, East Baton Rouge, East Feliciana and 20 more | 9 hr |
| Dec 25, 3:44 PM CST | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberia, Iberville and 19 more | 91 min |
| Dec 25, 9:31 AM CST | Mesoscale Discussion | SPC | Archer, Baylor, Clay, Cooke, Denton, Hood and 10 more | 5 hr |
| Dec 25, 11:02 AM CST | Mesoscale Discussion | SPC | Wichita, Wilbarger | 4 hr |
| Dec 25, 2:50 PM CST | Mesoscale Discussion | SPC | Clay, Wichita, Wilbarger | 4 hr |
Nearby
Severe Thunderstorm Watches in Louisiana, 2012Severe Thunderstorm Watches in Texas, 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.