Alert archive / Mississippi / Tornado Watches in 2017
Tornado Watch 475
The Storm Prediction Center issued this tornado watch at Aug 30, 2017, 10:22 AM CDT for 14 parishes in Louisiana; 46 counties in Mississippi. It was in force for 8 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 30, 2017, 10:22 AM CDT (15:22 UTC)
- Expired
- Aug 30, 2017, 6:00 PM CDT
- In force
- 8 hr
- Issued by
- the Storm Prediction Center
- Largest hail expected
- 0.5 in
- Strongest gust expected
- 55 kt
All 60 counties
Catahoula Parish, LA, Concordia Parish, LA, East Carroll Parish, LA, East Feliciana Parish, LA, Franklin Parish, LA, Madison Parish, LA, Morehouse Parish, LA, Richland Parish, LA, Saint Helena Parish, LA, Saint Tammany Parish, LA, Tangipahoa Parish, LA, Tensas Parish, LA, Washington Parish, LA, West Carroll Parish, LA, Adams County, MS, Amite County, MS, Attala County, MS, Claiborne 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, Hinds County, MS, Holmes County, MS, Humphreys County, MS, Issaquena 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, Leake County, MS, Lincoln County, MS, Madison 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, Sharkey County, MS, Simpson County, MS, Smith County, MS, Stone County, MS, Walthall County, MS, Warren County, MS, Wayne County, MS, Wilkinson County, MS, Yazoo County, MS
The radar
The Jackson/Brandon,MS radar (KDGX), 89 km from the middle of the area, began a volume at 15:25 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
- 30%
- Ten or more severe wind reports
- 20%
- One or more gusts of 65 knots or more
- 10%
- 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
- 30%
Warnings issued inside it
19 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 30, 10:26 AM CDT | Tornado Warning | MOB | Stone | 19 min |
| Aug 30, 10:38 AM CDT | Tornado Warning | JAN | Forrest, Lamar | 52 min |
| Aug 30, 10:43 AM CDT | Tornado Warning | JAN | Covington, Forrest, Jones, Lamar | 62 min |
| Aug 30, 11:34 AM CDT | Tornado Warning | MOB | George | 26 min |
| Aug 30, 11:47 AM CDT | Tornado Warning | LIX | Jackson | 28 min |
| Aug 30, 11:49 AM CDT | Tornado Warning | MOB | Perry | 41 min |
| Aug 30, 11:50 AM CDT | Tornado Warning | JAN | Forrest, Jones | 25 min |
| Aug 30, 11:55 AM CDT | Tornado Warning | JAN | Covington, Jefferson Davis, Marion | 65 min |
| Aug 30, 11:59 AM CDT | Tornado Warning | MOB | George, Greene | 46 min |
| Aug 30, 12:14 PM CDT | Tornado Warning | LIX | Jackson | 31 min |
| Aug 30, 12:18 PM CDT | Tornado Warning | JAN | Forrest, Jones | 57 min |
| Aug 30, 12:33 PM CDT | Severe Thunderstorm Warning | MOB | George | 42 min |
| Aug 30, 12:55 PM CDT | Severe Thunderstorm Warning | JAN | Claiborne, Copiah, Franklin, Jefferson, Lincoln | 50 min |
| Aug 30, 12:59 PM CDT | Tornado Warning | MOB | Greene | 22 min |
| Aug 30, 1:06 PM CDT | Severe Thunderstorm Warning | MOB | Greene | 39 min |
| Aug 30, 1:14 PM CDT | Severe Thunderstorm Warning | JAN | Forrest | 46 min |
| Aug 30, 1:20 PM CDT | Severe Thunderstorm Warning | MOB | Perry, Stone | 40 min |
| Aug 30, 1:27 PM CDT | Severe Thunderstorm Warning | LIX | Harrison | 33 min |
| Aug 30, 2:45 PM CDT | Tornado Warning | JAN | Hinds, Warren | 33 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, 3.4 hours before the alert went out and 95 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
- 273 J/kg
- Mixed-layer CIN
- -30 J/kg
- Mixed-layer LCL
- 523 m above ground
- 0-6 km bulk shear
- 31 kt
- 0-1 km storm-relative helicity
- 235 m²/s²
- 0-3 km storm-relative helicity
- 218 m²/s²
- Significant tornado parameter
- 0.3
- Supercell composite
- 3.0
The text
As transmitted.
197 WWUS20 KWNS 301519 SEL5 SPC WW 301519 LAZ000-MSZ000-302300- URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 475 NWS Storm Prediction Center Norman OK 1020 AM CDT Wed Aug 30 2017 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of Eastern Louisiana Central and southern Mississippi * Effective this Wednesday morning and evening from 1020 AM until 600 PM CDT. * Primary threats include... A few tornadoes likely with a couple intense tornadoes possible Isolated damaging wind gusts to 65 mph possible SUMMARY...Multiple convective bands associated with Tropical Cyclone Harvey will offer a risk for brief tornadoes into this evening. The tornado watch area is approximately along and 80 statute miles either side of a line from 50 miles east of Pine Belt MS to 45 miles northwest of Natchez 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. && AVIATION...Tornadoes and a few severe thunderstorms with hail surface and aloft to 0.5 inches. Extreme turbulence and surface wind gusts to 55 knots. A few cumulonimbi with maximum tops to 450. Mean storm motion vector 19030. ...Grams
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 30, 1:00 AM CDT | Mesoscale Discussion | SPC | Orleans, Saint Bernard, Saint John the Baptist, Saint Tammany, Tangipahoa, Washington | 90 min |
| Aug 30, 9:51 AM CDT | Mesoscale Discussion | SPC | Catahoula, Concordia, East Feliciana, Franklin, LaSalle, Saint Helena and 4 more | 114 min |
| Aug 30, 2:55 PM CDT | Mesoscale Discussion | SPC | East Carroll, Madison | 2 hr |
| Aug 30, 5:50 PM CDT | Mesoscale Discussion | SPC | Avoyelles, Catahoula, Concordia, East Carroll, East Feliciana, Franklin and 8 more | 55 min |
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.