Alert archive / Mississippi / Tornado Watches in 2017

Tornado Watch 181

April 30, 201720 parishes in Louisiana; 48 counties in Mississippi

The Storm Prediction Center issued this tornado watch at Apr 30, 2017, 7:32 AM CDT for 20 parishes in Louisiana; 48 counties in Mississippi. It was in force for 7 hr.

The area

The outline as issued.

The facts

Issued
Apr 30, 2017, 7:32 AM CDT (12:32 UTC)
Expired
Apr 30, 2017, 3:00 PM CDT
In force
7 hr
Issued by
the Storm Prediction Center
Largest hail expected
2 in
Strongest gust expected
60 kt
All 68 counties

Ascension Parish, LA, Assumption 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, 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, Amite County, MS, Attala County, MS, Carroll County, MS, Choctaw County, MS, Clarke County, MS, Clay County, MS, Copiah County, MS, Covington County, MS, Forrest County, MS, George County, MS, Greene County, MS, Grenada County, MS, Hancock County, MS, Harrison County, MS, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Jackson County, MS, Jasper County, MS, Jefferson Davis County, MS, Jones County, MS, Kemper County, MS, Lamar County, MS, Lauderdale County, MS, Lawrence County, MS, Leake County, MS, Lincoln County, MS, Lowndes County, MS, Madison County, MS, Marion County, MS, Montgomery County, MS, Neshoba County, MS, Newton County, MS, Noxubee County, MS, Oktibbeha 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, Webster County, MS, Winston County, MS, Yazoo County, MS

The radar

The Jackson/Brandon,MS radar (KDGX), 42 km from the middle of the area, began a volume at 12:34 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
60%
One or more EF2 to EF5 tornadoes
20%
Ten or more severe wind reports
40%
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
80%

Warnings issued inside it

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

IssuedProductOfficeCountiesLasted
Apr 30, 7:35 AM CDTSevere Thunderstorm WarningJANCopiah, Franklin, Lincoln40 min
Apr 30, 7:42 AM CDTTornado WarningLIXEast Baton Rouge, East Feliciana, West Baton Rouge33 min
Apr 30, 7:56 AM CDTSevere Thunderstorm WarningLIXEast Feliciana, Saint Helena34 min
Apr 30, 7:56 AM CDTSevere Thunderstorm WarningJANCopiah, Hinds, Madison, Rankin, Simpson64 min
Apr 30, 7:57 AM CDTTornado WarningJANHinds48 min
Apr 30, 7:59 AM CDTTornado WarningLIXEast Baton Rouge, Livingston, Saint Helena, Tangipahoa31 min
Apr 30, 8:01 AM CDTTornado WarningJANCopiah, Hinds, Rankin44 min
Apr 30, 8:05 AM CDTTornado WarningLIXEast Baton Rouge, East Feliciana, Saint Helena25 min
Apr 30, 8:06 AM CDTSevere Thunderstorm WarningJANHumphreys, Yazoo54 min
Apr 30, 8:12 AM CDTFlash Flood WarningJANFranklin, Lincoln3 hr
Apr 30, 8:13 AM CDTTornado WarningJANHinds, Madison, Warren, Yazoo62 min
Apr 30, 8:20 AM CDTTornado WarningJANHolmes, Humphreys, Yazoo55 min
Apr 30, 8:26 AM CDTTornado WarningLIXAscension, East Baton Rouge, East Feliciana, Iberville, Livingston, Saint Helena and 1 more34 min
Apr 30, 8:31 AM CDTTornado WarningJANHinds, Madison59 min
Apr 30, 8:53 AM CDTTornado WarningLIXSaint Helena, Tangipahoa, Washington37 min
Apr 30, 8:57 AM CDTSevere Thunderstorm WarningLIXAscension, Assumption, Lafourche, Livingston, Saint Helena, Saint James and 4 more33 min
Apr 30, 8:59 AM CDTSevere Thunderstorm WarningJANRankin, Scott, Simpson, Smith61 min
Apr 30, 9:00 AM CDTFlash Flood WarningJANHumphreys, Issaquena, Sharkey, Warren, Yazoo3 hr
Apr 30, 9:05 AM CDTTornado Warning Tornado observedJANAttala, Holmes, Madison, Yazoo55 min
Apr 30, 9:09 AM CDTSevere Thunderstorm WarningJANCarroll, Holmes, Humphreys, Leflore66 min
Apr 30, 9:18 AM CDTTornado WarningJANScott42 min
Apr 30, 9:28 AM CDTTornado WarningLIXWashington32 min
Apr 30, 9:30 AM CDTFlash Flood WarningJANAttala, Holmes, Humphreys, Madison3 hr
Apr 30, 9:31 AM CDTSevere Thunderstorm WarningLIXSaint Tammany, Tangipahoa, Washington44 min
Apr 30, 9:37 AM CDTTornado WarningJANCarroll, Holmes, Montgomery53 min
Apr 30, 9:48 AM CDTTornado Warning Tornado observedJANLeake, Neshoba, Newton, Scott57 min
Apr 30, 9:50 AM CDTSevere Thunderstorm WarningJANGrenada, Leflore40 min
Apr 30, 9:50 AM CDTSevere Thunderstorm WarningJANCovington, Jefferson Davis, Lamar, Marion55 min
Apr 30, 9:53 AM CDTSevere Thunderstorm WarningJANAttala, Montgomery, Webster52 min
Apr 30, 9:54 AM CDTFlash Flood WarningJANCopiah, Covington, Jefferson Davis, Lawrence, Simpson, Smith3 hr
Apr 30, 10:05 AM CDTTornado WarningJANMontgomery, Webster27 min
Apr 30, 10:07 AM CDTSevere Thunderstorm WarningJANKemper, Lauderdale, Neshoba, Newton38 min
Apr 30, 10:16 AM CDTSevere Thunderstorm WarningJANGrenada, Montgomery22 min
Apr 30, 10:22 AM CDTTornado WarningJANGrenada23 min
Apr 30, 10:31 AM CDTTornado WarningLIXSaint Tammany, Tangipahoa14 min
Apr 30, 10:33 AM CDTSevere Thunderstorm WarningJANNoxubee, Winston57 min
Apr 30, 10:43 AM CDTSevere Thunderstorm WarningJANCovington, Forrest, Jones, Lamar62 min
Apr 30, 10:45 AM CDTSevere Thunderstorm WarningJANKemper, Lauderdale, Noxubee60 min
Apr 30, 10:59 AM CDTTornado WarningJANKemper, Noxubee43 min
Apr 30, 11:12 AM CDTFlash Flood WarningJANCovington, Forrest, Jones, Lamar, Marion3 hr
Apr 30, 11:24 AM CDTSevere Thunderstorm WarningJANLowndes36 min
Apr 30, 11:33 AM CDTFlash Flood WarningJANCovington, Forrest, Jones3 hr
Apr 30, 11:34 AM CDTSevere Thunderstorm WarningMOBGreene, Perry, Wayne41 min
Apr 30, 11:42 AM CDTTornado WarningJANLowndes8 min
Apr 30, 12:16 PM CDTSevere Thunderstorm WarningMOBGeorge, Greene, Perry, Stone44 min
Apr 30, 12:29 PM CDTTornado WarningLIXHancock, Harrison31 min
Apr 30, 12:31 PM CDTSevere Thunderstorm WarningJANForrest, Jones34 min
Apr 30, 12:40 PM CDTSevere Thunderstorm WarningLIXJefferson, Lafourche20 min
Apr 30, 1:02 PM CDTSevere Thunderstorm WarningMOBGeorge, Greene, Perry, Stone58 min
Apr 30, 1:06 PM CDTSevere Thunderstorm WarningMOBWayne39 min
Apr 30, 1:46 PM CDTSevere Thunderstorm WarningMOBGreene, Wayne59 min
Apr 30, 2:00 PM CDTSevere Thunderstorm WarningMOBGeorge, Greene, Perry, Stone60 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

Jackson, MS (KJAN), launched 12:00Z, 0.5 hours before the alert went out and 49 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-pSkew-T log-p diagram, Jackson, MS at 12:00Z on 2017-04-30Temperature and dew point through the depth of the atmosphere, with the mixed-layer parcel. CAPE 647 joules per kilogram.LCLLFCEL10008507005003002001001 km2 km3 km6 km9 km12 km15 km-30°-20°-10°0°10°20°30°40°
Temperature in red, dew point in green, the mixed-layer parcel dashed.
HodographHodograph, Jackson, MS at 12:00Z on 2017-04-30The wind through the lowest 10 kilometers. Zero to 1 km storm-relative helicity 221 square meters per square second.19395878Sfc1 km3 km6 km9 kmRMLM
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
647 J/kg
Mixed-layer CIN
-84 J/kg
Mixed-layer LCL
920 m above ground
0-6 km bulk shear
32 kt
0-1 km storm-relative helicity
221 m²/s²
0-3 km storm-relative helicity
398 m²/s²
Significant tornado parameter
0.7
Supercell composite
3.0

Open this sounding in Storm Lab

The text

As transmitted.

950 
WWUS20 KWNS 301228
SEL1  
SPC WW 301228
LAZ000-MSZ000-CWZ000-302000-

URGENT - IMMEDIATE BROADCAST REQUESTED
Tornado Watch Number 181
NWS Storm Prediction Center Norman OK
730 AM CDT Sun Apr 30 2017

The NWS Storm Prediction Center has issued a

* Tornado Watch for portions of 
  Southeast Louisiana
  Central and southern Mississippi
  Coastal Waters

* Effective this Sunday morning and afternoon from 730 AM until
  300 PM CDT.

* 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...Bands of severe storms will continue east-northeastward
through the morning and early afternoon hours across much of
Mississippi and east/southeast Louisiana. Strong low-level shear and
moist air mass will support the possibility of tornadoes along with
damaging winds and some hail.

The tornado watch area is approximately along and 60 statute miles
east and west of a line from 85 miles north northwest of Meridian MS
to 30 miles south of New Orleans LA. For a complete depiction of the
watch see the associated watch outline update (WOUS64 KWNS WOU1).

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 180...

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 600. Mean
storm motion vector 23035.

...Guyer

SPC that day

Everything else SPC issued on the same UTC day.

IssuedProductOfficeCountiesLasted
Apr 29, 9:38 PM CDTMesoscale DiscussionSPCBossier, Caddo, De Soto, Sabine, Webster67 min
Apr 29, 10:23 PM CDTSevere Thunderstorm WatchSPCBienville, Bossier, Caddo, Caldwell, Claiborne, De Soto and 11 more8 hr
Apr 29, 11:37 PM CDTMesoscale DiscussionSPCBienville, Bossier, Caddo, Claiborne, De Soto, Lincoln and 5 more53 min
Apr 30, 1:14 AM CDTMesoscale DiscussionSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Caldwell and 20 more91 min
Apr 30, 1:49 AM CDTTornado WatchSPCAcadia, Allen, Avoyelles, Beauregard, Calcasieu, Cameron and 21 more7 hr
Apr 30, 3:36 AM CDTMesoscale DiscussionSPCCaldwell, Grant, Jackson, LaSalle, Lincoln, Natchitoches and 3 more84 min
Apr 30, 5:41 AM CDTMesoscale DiscussionSPCUnion64 min
Apr 30, 6:12 AM CDTMesoscale DiscussionSPCAcadia, Avoyelles, Concordia, East Baton Rouge, East Carroll, East Feliciana and 16 more93 min
Apr 30, 6:59 AM CDTMesoscale DiscussionSPCAscension, Assumption, East Baton Rouge, East Feliciana, Jefferson, Lafourche and 12 more2 hr
Apr 30, 12:54 AM CDTMesoscale DiscussionSPCBolivar, Coahoma, DeSoto, Panola, Quitman, Sunflower and 3 more96 min
Apr 30, 1:10 AM CDTSevere Thunderstorm WatchSPCDeSoto, Tunica6 hr
Apr 30, 2:58 AM CDTMesoscale DiscussionSPCDeSoto, Marshall, Tate, Tunica92 min
Apr 30, 10:06 AM CDTMesoscale DiscussionSPCChickasaw, Itawamba, Lee, Monroe, Pontotoc, Prentiss and 2 more84 min
Apr 30, 10:36 AM CDTTornado WatchSPCAlcorn, Benton, Calhoun, Chickasaw, Itawamba, Lafayette and 9 more8 hr

Nearby

Tornado Watches in Mississippi, 2017Tornado Watches in Louisiana, 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; radar from the NEXRAD Level II archive.