Alert archive / Louisiana / Tornado Watches in 2017
Tornado Watch 15
The Storm Prediction Center issued this tornado watch at Jan 21, 2017, 3:29 PM CST for 28 parishes in Louisiana; 20 counties in Mississippi. It was in force for 6 hr.
The area
The outline as issued.
The facts
- Issued
- Jan 21, 2017, 3:29 PM CST (21:29 UTC)
- Expired
- Jan 21, 2017, 9:00 PM CST
- In force
- 6 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 2.5 in
- Strongest gust expected
- 60 kt
All 48 counties
Acadia Parish, LA, Ascension Parish, LA, Avoyelles Parish, LA, Catahoula Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Evangeline Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafayette Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee Parish, LA, Rapides Parish, LA, Saint Bernard Parish, LA, Saint Charles Parish, LA, Saint Helena Parish, LA, Saint James Parish, LA, Saint John the Baptist Parish, LA, Saint Landry Parish, LA, Saint Martin 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, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson 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
What SPC expected
The probabilities SPC published with the watch, for the watch area over its life.
- Two or more tornadoes
- 50%
- One or more EF2 to EF5 tornadoes
- 30%
- Ten or more severe wind reports
- 30%
- One or more gusts of 65 knots or more
- 10%
- Ten or more severe hail reports
- 60%
- One or more hailstones of 2 inches or more
- 40%
- Six or more combined severe hail and wind reports
- 70%
Warnings issued inside it
23 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 21, 4:56 PM CST | Severe Thunderstorm Warning | LIX | Saint Charles | 19 min |
| Jan 21, 5:02 PM CST | Tornado Warning | LIX | Orleans | 13 min |
| Jan 21, 5:11 PM CST | Tornado Warning | LIX | Saint Charles | 7 min |
| Jan 21, 5:16 PM CST | Severe Thunderstorm Warning | LIX | Saint Tammany | 29 min |
| Jan 21, 5:47 PM CST | Severe Thunderstorm Warning | LIX | Pointe Coupee, West Feliciana | 28 min |
| Jan 21, 6:18 PM CST | Severe Thunderstorm Warning | MOB | George | 42 min |
| Jan 21, 6:21 PM CST | Severe Thunderstorm Warning | LIX | Jackson | 24 min |
| Jan 21, 6:50 PM CST | Severe Thunderstorm Warning | LCH | Rapides | 14 min |
| Jan 21, 6:57 PM CST | Severe Thunderstorm Warning | LIX | East Baton Rouge, East Feliciana, Pointe Coupee, West Baton Rouge | 33 min |
| Jan 21, 7:08 PM CST | Severe Thunderstorm Warning | JAN | Catahoula, Concordia | 82 min |
| Jan 21, 7:11 PM CST | Severe Thunderstorm Warning | MOB | George, Greene | 34 min |
| Jan 21, 7:24 PM CST | Tornado Warning | JAN | Catahoula, Concordia | 66 min |
| Jan 21, 7:40 PM CST | Severe Thunderstorm Warning | MOB | George | 28 min |
| Jan 21, 7:49 PM CST | Severe Thunderstorm Warning | JAN | Forrest | 26 min |
| Jan 21, 7:56 PM CST | Severe Thunderstorm Warning | MOB | Perry | 49 min |
| Jan 21, 8:09 PM CST | Severe Thunderstorm Warning | JAN | Jefferson | 36 min |
| Jan 21, 8:18 PM CST | Severe Thunderstorm Warning | JAN | Concordia, Tensas | 57 min |
| Jan 21, 8:28 PM CST | Severe Thunderstorm Warning | MOB | Greene, Perry, Wayne | 47 min |
| Jan 21, 8:31 PM CST | Tornado Warning | JAN | Concordia | 41 min |
| Jan 21, 8:36 PM CST | Tornado Warning | JAN | Copiah, Franklin, Jefferson, Lincoln | 54 min |
| Jan 21, 8:43 PM CST | Tornado Warning | JAN | Catahoula, Concordia | 17 min |
| Jan 21, 8:50 PM CST | Severe Thunderstorm Warning | JAN | Forrest, Lamar | 55 min |
| Jan 21, 8:52 PM CST | Severe Thunderstorm Warning | MOB | Perry, Wayne | 38 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
Slidell Radar S, LA (KSIL), launched 12:00Z, 9.5 hours before the alert went out and 136 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
- 1327 J/kg
- Mixed-layer CIN
- 0 J/kg
- Mixed-layer LCL
- 508 m above ground
- 0-6 km bulk shear
- 51 kt
- 0-1 km storm-relative helicity
- 275 m²/s²
- 0-3 km storm-relative helicity
- 323 m²/s²
- Significant tornado parameter
- 2.4
- Supercell composite
- 11.2
The text
As transmitted.
171
WWUS20 KWNS 212126
SEL5
SPC WW 212126
LAZ000-MSZ000-CWZ000-220300-
URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 15
NWS Storm Prediction Center Norman OK
330 PM CST Sat Jan 21 2017
The NWS Storm Prediction Center has issued a
* Tornado Watch for portions of
Southeast Louisiana
Southern Mississippi
Coastal Waters
* Effective this Saturday afternoon and evening from 330 PM until
900 PM CST.
* Primary threats include...
A few tornadoes and a couple intense tornadoes possible
Scattered large hail likely with isolated very large hail events
to 2.5 inches in diameter possible
Isolated damaging wind gusts to 70 mph possible
SUMMARY...Thunderstorms are expected to develop over southeast LA
this afternoon and spread northeastward across the watch area.
Large hail and damaging winds are possible in this area, but the
risk of a few tornadoes should increase by early evening.
The tornado watch area is approximately along and 70 statute miles
north and south of a line from 10 miles south of Alexandria LA to 35
miles east southeast of Gulfport MS. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU5).
PRECAUTIONARY/PREPAREDNESS ACTIONS...
REMEMBER...A Tornado Watch means conditions are favorable for
tornadoes and 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.
&&
OTHER WATCH INFORMATION...CONTINUE...WW 13...WW 14...
AVIATION...Tornadoes and a few severe thunderstorms with hail
surface and aloft to 2.5 inches. Extreme turbulence and surface wind
gusts to 60 knots. A few cumulonimbi with maximum tops to 450. Mean
storm motion vector 24030.
...HartSPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Jan 20, 6:37 PM CST | Mesoscale Discussion | SPC | Acadia, Allen, Beauregard, Calcasieu, Cameron, Evangeline and 3 more | 113 min |
| Jan 20, 7:32 PM CST | Tornado Watch | SPC | Acadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 9 more | 6 hr |
| Jan 20, 10:04 PM CST | Mesoscale Discussion | SPC | Acadia, Allen, Avoyelles, Calcasieu, Cameron, Evangeline and 7 more | 116 min |
| Jan 20, 10:44 PM CST | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more | 61 min |
| Jan 20, 11:00 PM CST | Tornado Watch | SPC | Ascension, Assumption, Concordia, East Baton Rouge, East Feliciana, Iberville and 17 more | 8 hr |
| Jan 21, 1:41 AM CST | Mesoscale Discussion | SPC | Acadia, Avoyelles, Cameron, Evangeline, Iberia, Jefferson Davis and 5 more | 64 min |
| Jan 21, 2:55 AM CST | Mesoscale Discussion | SPC | Ascension, Assumption, East Baton Rouge, East Feliciana, Iberville, Jefferson and 16 more | 2 hr |
| Jan 21, 6:35 AM CST | Mesoscale Discussion | SPC | Jefferson, Lafourche, Orleans, Plaquemines, Saint Bernard, Saint Charles and 1 more | 55 min |
| Jan 21, 2:33 PM CST | Mesoscale Discussion | SPC | Bienville, Bossier, Caddo, Claiborne, De Soto, Jackson and 8 more | 2 hr |
| Jan 21, 2:34 PM CST | Mesoscale Discussion | SPC | Allen, Ascension, Avoyelles, Catahoula, Concordia, East Baton Rouge and 16 more | 2 hr |
| Jan 21, 3:41 PM CST | Tornado Watch | SPC | Bienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more | 7 hr |
| Jan 21, 5:32 PM CST | Mesoscale Discussion | SPC | Avoyelles, Bienville, Bossier, Caddo, Caldwell, Catahoula and 23 more | 118 min |
Nearby
Tornado Watches in Louisiana, 2017Tornado Watches in Mississippi, 2017Every tornado watch 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.