Alert archive / Louisiana / Tornado Watches in 2017
Tornado Watch 473
The Storm Prediction Center issued this tornado watch at Aug 28, 2017, 1:51 AM CDT for 6 parishes in Louisiana; 5 counties in Texas. It was in force for 10 hr.
The area
The outline as issued.
The facts
- Issued
- Aug 28, 2017, 1:51 AM CDT (06:51 UTC)
- Expired
- Aug 28, 2017, 12:17 PM CDT
- In force
- 10 hr
- Issued by
- the Storm Prediction Center
- Strongest gust expected
- 60 kt
Counties Acadia Parish, LA, Calcasieu Parish, LA, Cameron Parish, LA, Iberia Parish, LA, Jefferson Davis Parish, LA, Vermilion Parish, LA, Chambers County, TX, Hardin County, TX, Jefferson County, TX, Liberty County, TX, Orange County, TX
The radar
The Lake Charles radar (KLCH), 51 km from the middle of the area, began a volume at 06:49 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
- 50%
- One or more EF2 to EF5 tornadoes
- 20%
- Ten or more severe wind reports
- 5%
- One or more gusts of 65 knots or more
- 5%
- 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
18 tornado, severe thunderstorm and flash flood warnings for its counties while it was in force.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 28, 2:10 AM CDT | Tornado Warning | HGX | Chambers, Galveston | 20 min |
| Aug 28, 3:42 AM CDT | Tornado Warning | LCH | Jefferson | 38 min |
| Aug 28, 5:10 AM CDT | Severe Thunderstorm Warning | LCH | Cameron | 35 min |
| Aug 28, 5:42 AM CDT | Flash Flood Warning | LCH | Hardin, Jasper, Jefferson, Orange | 12 hr |
| Aug 28, 6:53 AM CDT | Tornado Warning | LCH | Acadia | 37 min |
| Aug 28, 7:34 AM CDT | Flash Flood Warning | LCH | Acadia | 5 hr |
| Aug 28, 7:43 AM CDT | Tornado Warning | LCH | Allen, Jefferson Davis | 47 min |
| Aug 28, 7:52 AM CDT | Tornado Warning | LCH | Cameron, Vermilion | 38 min |
| Aug 28, 7:54 AM CDT | Flash Flood Warning | LCH | Beauregard, Calcasieu, Cameron, Jefferson Davis | 11 hr |
| Aug 28, 8:14 AM CDT | Flash Flood Warning | LCH | Allen, Beauregard, Jefferson Davis, Vernon | 11 hr |
| Aug 28, 8:27 AM CDT | Tornado Warning | LCH | Cameron, Vermilion | 33 min |
| Aug 28, 8:28 AM CDT | Tornado Warning | LCH | Cameron, Vermilion | 32 min |
| Aug 28, 8:40 AM CDT | Tornado Warning | LCH | Iberia, St. Mary | 35 min |
| Aug 28, 9:00 AM CDT | Tornado Warning | LCH | Calcasieu | 17 min |
| Aug 28, 9:37 AM CDT | Flash Flood Warning | LCH | Acadia, Iberia, Lafayette, Saint Landry, Saint Martin, St. Mary and 1 more | 13 hr |
| Aug 28, 9:50 AM CDT | Flash Flood Warning | HGX | Brazoria, Chambers, Fort Bend, Galveston, Harris | 115 min |
| Aug 28, 11:35 AM CDT | Flash Flood Warning | HGX | Chambers, Galveston, Liberty | 115 min |
| Aug 28, 12:05 PM CDT | Tornado Warning | LCH | Iberia, Saint Martin, St. Mary | 25 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 00:00Z, 6.9 hours before the alert went out and 52 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
- 311 J/kg
- Mixed-layer CIN
- -31 J/kg
- Mixed-layer LCL
- 714 m above ground
- 0-6 km bulk shear
- 36 kt
- 0-1 km storm-relative helicity
- 148 m²/s²
- 0-3 km storm-relative helicity
- 253 m²/s²
- Significant tornado parameter
- 0.2
- Supercell composite
- 1.4
The text
As transmitted.
125 WWUS20 KWNS 280648 SEL3 SPC WW 280648 LAZ000-TXZ000-CWZ000-281800- URGENT - IMMEDIATE BROADCAST REQUESTED Tornado Watch Number 473 NWS Storm Prediction Center Norman OK 145 AM CDT Mon Aug 28 2017 The NWS Storm Prediction Center has issued a * Tornado Watch for portions of South-central and southwestern Louisiana Southeast Texas Coastal Waters * Effective this Monday morning and afternoon from 145 AM until 100 PM CDT. * Primary threats include... A few tornadoes possible SUMMARY...The lingering threat for supercells and a few tornadoes with Harvey is slowly shifting eastward as its path curves back toward the middle Texas coast, and is forecast by NHC to shift further eastward through today. Relatively stable air away from the coast will continue to limit the inland extent of the risk through midday. The tornado watch area is approximately along and 85 statute miles east and west of a line from 35 miles north northeast of Port Arthur TX to 45 miles south southeast of Lake Charles LA. For a complete depiction of the watch see the associated watch outline update (WOUS64 KWNS WOU3). 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...This tornado watch replaces tornado watch number 471. Watch number 471 will not be in effect after 145 AM CDT. AVIATION...TORNADOES and A FEW SEVERE THUNDERSTORMS WITH EXTREME TURBULENCE and SURFACE WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM MOTION VECTOR 16030. ...Edwards
SPC that day
Everything else SPC issued on the same UTC day.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| Aug 27, 9:50 PM CDT | Mesoscale Discussion | SPC | Acadia, Calcasieu, Cameron, Jefferson Davis, Vermilion | 115 min |
| Aug 28, 11:37 AM CDT | Mesoscale Discussion | SPC | Acadia, Ascension, Assumption, Calcasieu, Cameron, Iberia and 13 more | 83 min |
| Aug 28, 12:16 PM CDT | Tornado Watch | SPC | Acadia, Ascension, Assumption, Calcasieu, Cameron, East Baton Rouge and 20 more | 12 hr |
| Aug 28, 3:58 PM CDT | Mesoscale Discussion | SPC | Acadia, Calcasieu, Cameron, Iberia, Jefferson Davis, Lafayette and 3 more | 92 min |
| Aug 28, 6:49 PM CDT | Mesoscale Discussion | SPC | Acadia, Ascension, Assumption, Calcasieu, Cameron, Iberia and 16 more | 116 min |
| Aug 27, 7:45 PM CDT | Mesoscale Discussion | SPC | Carson, Dallam, Hansford, Hartley, Hutchinson, Moore and 3 more | 2 hr |
| Aug 28, 3:00 AM CDT | Mesoscale Discussion | SPC | Jefferson | 60 min |
Nearby
Tornado Watches in Louisiana, 2017Tornado Watches in Texas, 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.