Alert archive / Mississippi / Tornado Watches in 2017

Tornado Watch 10

January 20, 201723 parishes in Louisiana; 35 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Jan 20, 2017, 11:00 PM CST for 23 parishes in Louisiana; 35 counties in Mississippi. It was in force for 8 hr.

The area

The outline as issued.

The facts

Issued: Jan 20, 2017, 11:00 PM CST (05:00 UTC)
Expired: Jan 21, 2017, 7:00 AM CST
In force: 8 hr
Issued by: the Storm Prediction Center
Largest hail expected: 2 in
Strongest gust expected: 60 kt

All 58 counties

Ascension Parish, LA, Assumption Parish, LA, Concordia Parish, LA, East Baton Rouge Parish, LA, East Feliciana Parish, LA, Iberville Parish, LA, Jefferson Parish, LA, Lafourche Parish, LA, Livingston Parish, LA, Orleans Parish, LA, Plaquemines Parish, LA, Pointe Coupee 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 Tammany Parish, LA, Tangipahoa Parish, LA, Terrebonne Parish, LA, Washington Parish, LA, West Baton Rouge Parish, LA, West Feliciana Parish, LA, Adams County, MS, Amite County, MS, Clarke County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, Franklin County, MS, George County, MS, Greene County, MS, Hancock County, MS, Harrison County, MS, Jackson County, MS, Jasper County, MS, Jefferson County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Lincoln County, MS, Marion County, MS, Neshoba County, MS, Newton County, MS, Pearl River County, MS, Perry County, MS, Pike County, MS, Rankin County, MS, Scott County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Wayne 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: 60%
One or more EF2 to EF5 tornadoes: 20%
Ten or more severe wind reports: 50%
One or more gusts of 65 knots or more: 10%
Ten or more severe hail reports: 30%
One or more hailstones of 2 inches or more: 30%
Six or more combined severe hail and wind reports: 90%

Warnings issued inside it

42 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.

Issued	Product	Office	Counties	Lasted
Jan 20, 11:01 PM CST	Severe Thunderstorm Warning	LIX	Pointe Coupee, West Feliciana	29 min
Jan 20, 11:15 PM CST	Tornado Warning	LIX	Pointe Coupee, West Feliciana	30 min
Jan 20, 11:43 PM CST	Tornado Warning	LIX	West Feliciana	32 min
Jan 21, 12:12 AM CST	Severe Thunderstorm Warning	LIX	Wilkinson	33 min
Jan 21, 12:24 AM CST	Severe Thunderstorm Warning	JAN	Adams, Franklin	66 min
Jan 21, 12:26 AM CST	Tornado Warning	LIX	Amite, Wilkinson	14 min
Jan 21, 12:51 AM CST	Severe Thunderstorm Warning	JAN	Concordia	54 min
Jan 21, 1:06 AM CST	Severe Thunderstorm Warning	LIX	Pointe Coupee, West Feliciana	24 min
Jan 21, 1:14 AM CST	Tornado Warning	LIX	Wilkinson	31 min
Jan 21, 1:19 AM CST	Severe Thunderstorm Warning	JAN	Copiah, Lincoln	56 min
Jan 21, 1:29 AM CST	Severe Thunderstorm Warning	LIX	Wilkinson	31 min
Jan 21, 1:38 AM CST	Severe Thunderstorm Warning	JAN	Franklin	52 min
Jan 21, 1:41 AM CST	Severe Thunderstorm Warning	LIX	Pointe Coupee, West Feliciana	34 min
Jan 21, 2:02 AM CST	Severe Thunderstorm Warning	JAN	Rankin, Simpson	58 min
Jan 21, 2:14 AM CST	Severe Thunderstorm Warning	LIX	East Baton Rouge, East Feliciana, Pointe Coupee, Saint Helena, West Feliciana	46 min
Jan 21, 2:20 AM CST	Tornado Warning	LIX	Livingston, Saint Helena, Tangipahoa	25 min
Jan 21, 2:22 AM CST	Severe Thunderstorm Warning	JAN	Lawrence, Lincoln	53 min
Jan 21, 2:28 AM CST	Severe Thunderstorm Warning	LIX	Tangipahoa, Washington	32 min
Jan 21, 2:29 AM CST	Severe Thunderstorm Warning	JAN	Covington, Jefferson Davis, Marion	61 min
Jan 21, 2:48 AM CST	Tornado Warning	LIX	East Baton Rouge, East Feliciana, Saint Helena	10 min
Jan 21, 2:57 AM CST	Severe Thunderstorm Warning	LIX	Washington	33 min
Jan 21, 2:57 AM CST	Severe Thunderstorm Warning	LIX	Saint Helena, Tangipahoa, Washington	48 min
Jan 21, 2:57 AM CST	Tornado Warning	JAN	Lamar, Marion	63 min
Jan 21, 3:02 AM CST	Tornado Warning	LIX	Washington	13 min
Jan 21, 3:04 AM CST	Tornado Warning	LIX	Washington	15 min
Jan 21, 3:07 AM CST	Severe Thunderstorm Warning	MOB	Wayne	23 min
Jan 21, 3:12 AM CST	Tornado Warning	JAN	Covington, Jasper, Jones, Smith	48 min
Jan 21, 3:20 AM CST	Flash Flood Warning	JAN	Adams, Claiborne, Copiah, Franklin, Jefferson, Lincoln	3 hr
Jan 21, 3:32 AM CST	Severe Thunderstorm Warning	JAN	Jones	43 min
Jan 21, 3:36 AM CST	Tornado Warning	JAN	Forrest, Jones, Lamar	54 min
Jan 21, 3:38 AM CST	Severe Thunderstorm Warning	JAN	Jefferson Davis, Marion	25 min
Jan 21, 3:52 AM CST	Tornado Warning Tornado observed	MOB	Perry, Wayne	38 min
Jan 21, 3:57 AM CST	Tornado Warning	JAN	Lamar	38 min
Jan 21, 4:03 AM CST	Severe Thunderstorm Warning	MOB	Wayne	42 min
Jan 21, 4:09 AM CST	Severe Thunderstorm Warning	JAN	Jasper	51 min
Jan 21, 4:24 AM CST	Severe Thunderstorm Warning	JAN	Forrest, Jones	42 min
Jan 21, 4:24 AM CST	Tornado Warning	JAN	Clarke	41 min
Jan 21, 4:24 AM CST	Tornado Warning	MOB	Wayne	51 min
Jan 21, 4:24 AM CST	Tornado Warning	MOB	Wayne	21 min
Jan 21, 4:31 AM CST	Flash Flood Warning	JAN	Covington, Forrest, Jefferson Davis, Jones, Lamar, Marion	4 hr
Jan 21, 5:22 AM CST	Severe Thunderstorm Warning	LIX	Saint Tammany, Washington	38 min
Jan 21, 6:08 AM CST	Severe Thunderstorm Warning	LIX	Jefferson, Orleans	37 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 00:00Z, 5.0 hours before the alert went out and 87 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.

Skew-T log-p

Temperature in red, dew point in green, the mixed-layer parcel dashed.

Hodograph

The wind turning with height, colored by layer: ground to 1 km, 1 to 3 km, 3 to 6 km, 6 to 10 km.

Mixed-layer CAPE: 628 J/kg
Mixed-layer CIN: -28 J/kg
Mixed-layer LCL: 857 m above ground
0-6 km bulk shear: 45 kt
0-1 km storm-relative helicity: 85 m²/s²
0-3 km storm-relative helicity: 150 m²/s²
Significant tornado parameter: 0.2
Supercell composite: 1.6

Open this sounding in Storm Lab

The text

As transmitted.

553 
WWUS20 KWNS 210458
SEL0  
SPC WW 210458
LAZ000-MSZ000-CWZ000-211300-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 10
NWS Storm Prediction Center Norman OK
1100 PM CST Fri Jan 20 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southeastern Louisiana
  Southern Mississippi
  Coastal Waters

* Effective this Friday night and Saturday morning from 1100 PM
  until 700 AM CST.

* Primary threats include...
  A few tornadoes likely
  Scattered damaging wind gusts to 70 mph possible
  Isolated very large hail events to 2 inches in diameter possible

SUMMARY...An expanding area of thunderstorms is expected to move
east-northeastward across this watch through the overnight hours,
into a favorably destabilizing and inland-spreading Gulf air mass. 
Other, more isolated activity is possible ahead of the main complex
as well.  Forecast ingredients support all modes of severe weather
including a tornado threat.  See SPC mesoscale discussion 83 for
initial meteorological details.

The tornado watch area is approximately along and 100 statute miles
north and south of a line from 40 miles southwest of Baton Rouge LA
to 60 miles east southeast of Pine Belt MS. For a complete depiction
of the watch see the associated watch outline update (WOUS64 KWNS
WOU0).

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 9...

AVIATION...Tornadoes and 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 25030.

...Edwards

SPC 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 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, 3:29 PM CST	Tornado Watch	SPC	Acadia, Ascension, Avoyelles, Catahoula, Concordia, East Baton Rouge and 22 more	6 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 Mississippi, 2017 Tornado Watches in Louisiana, 2017 Every 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.