Alert archive / Louisiana / Tornado Warnings in 2017

Tornado Warning 71, NWS Shreveport, LA

May 11, 2017Bossier Parish, Caddo Parish, Louisiana

NWS Shreveport, LA issued this tornado warning at May 11, 2017, 8:17 PM CDT for Bossier Parish, Caddo Parish, Louisiana. It was in force for 28 min. 1 report came from inside the area while it was in force.

The area

The outline as issued, with what was reported inside it.

The facts

Issued: May 11, 2017, 8:17 PM CDT (01:17 UTC)
Expired: May 11, 2017, 8:45 PM CDT
In force: 28 min
Issued by: NWS Shreveport, LA
Area: Storm-based polygon
Tornado: Radar indicated
Hail: 1.5 in

Counties Bossier Parish, LA, Caddo Parish, LA

The radar

The Shreveport radar (KSHV), 34 km from the middle of the area, began a volume at 01:21 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 was reported inside it

Time	Report	Where	Remark
May 11, 8:31 PM CDT	TORNADO	3 Sw Gilliam, LA	THIS TORNADO TOUCHED DOWN JUST WEST OF A RIDGE ON THE WEST SIDE OF INTERSTATE 49 JUST NORTH OF BLACK BAYOU, WHERE SEVERAL TREES WERE SNAPPED, WITH ONE OF THE TREES FALLING ON POWER LINES. THE TORNADO CROSSED INTERSTATE 49 SNAPPING ADDITIONAL TREES ADJACENT TO

Local storm reports filed while the alert was in force, from inside its polygon or its counties.

The watch it was issued in

The SPC watch in force over the same counties when this warning went out.

Issued	Product	Office	Lasted
May 11, 2:43 PM CDT	Severe Thunderstorm Watch	SPC	9 hr

The nearest sounding before it

Shreveport, LA (KBAD), launched 00:00Z, 1.3 hours before the alert went out and 34 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: 1602 J/kg
Mixed-layer CIN: -19 J/kg
Mixed-layer LCL: 920 m above ground
0-6 km bulk shear: 38 kt
0-1 km storm-relative helicity: 101 m²/s²
0-3 km storm-relative helicity: 152 m²/s²
Significant tornado parameter: 0.9
Supercell composite: 7.0

Open this sounding in Storm Lab

The text

As transmitted.

569 
WFUS54 KSHV 120117
TORSHV
LAC015-017-120145-
/O.NEW.KSHV.TO.W.0071.170512T0117Z-170512T0145Z/

BULLETIN - EAS ACTIVATION REQUESTED
Tornado Warning
National Weather Service Shreveport LA
817 PM CDT THU MAY 11 2017

The National Weather Service in Shreveport has issued a

* Tornado Warning for...
  Northwestern Caddo Parish in northwestern Louisiana...
  West central Bossier Parish in northwestern Louisiana...

* Until 845 PM CDT
    
* At 817 PM CDT, a severe thunderstorm capable of producing a tornado
  was located over Oil City, or 20 miles northwest of Shreveport,
  moving northeast at 35 mph.

  HAZARD...Tornado and ping pong ball size hail. 

  SOURCE...Radar indicated rotation. 

  IMPACT...Flying debris will be dangerous to those caught without 
           shelter. Mobile homes will be damaged or destroyed. 
           Damage to roofs, windows, and vehicles will occur.  Tree 
           damage is likely. 

* This dangerous storm will be near...
  Belcher around 830 PM CDT. 
  Hosston and Gilliam around 835 PM CDT. 

Other locations impacted by this tornadic thunderstorm include Alden
Bridge, Caddo Lake and Cavett.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 3268 9399 3275 9404 3291 9381 3275 9369
TIME...MOT...LOC 0117Z 237DEG 29KT 3274 9396 

TORNADO...RADAR INDICATED
HAIL...1.50IN

$$

13

2 follow-up statements

578 
WWUS54 KSHV 120124
SVSSHV

Severe Weather Statement
National Weather Service Shreveport LA
824 PM CDT THU MAY 11 2017

LAC015-017-120145-
/O.CON.KSHV.TO.W.0071.000000T0000Z-170512T0145Z/
Caddo LA-Bossier LA-
824 PM CDT THU MAY 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 845 PM CDT FOR
NORTHWESTERN CADDO AND WEST CENTRAL BOSSIER PARISHES...
    
At 822 PM CDT, a severe thunderstorm capable of producing a tornado 
was located 3 miles east northeast of Oil City, moving northeast at 
30 mph. Embedded in the line is another developing tornado 5 miles 
northwest of Oil City, moving southeast near 25 mph. 

HAZARD...Tornado and ping pong ball size hail. 

SOURCE...Radar indicated rotation. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely. 

This dangerous storm will be near...
  Belcher around 830 PM CDT. 
  Hosston and Gilliam around 835 PM CDT. 

Other locations impacted by this tornadic thunderstorm include Alden
Bridge, Caddo Lake and Cavett.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 3268 9399 3275 9404 3291 9381 3275 9369
TIME...MOT...LOC 0122Z 236DEG 27KT 3276 9392 

TORNADO...RADAR INDICATED
HAIL...1.50IN

$$

13

855 
WWUS54 KSHV 120132
SVSSHV

Severe Weather Statement
National Weather Service Shreveport LA
832 PM CDT THU MAY 11 2017

LAC015-017-120145-
/O.CON.KSHV.TO.W.0071.000000T0000Z-170512T0145Z/
Caddo LA-Bossier LA-
832 PM CDT THU MAY 11 2017

...A TORNADO WARNING REMAINS IN EFFECT UNTIL 845 PM CDT FOR
NORTHWESTERN CADDO AND WEST CENTRAL BOSSIER PARISHES...
    
At 832 PM CDT, a severe thunderstorm capable of producing a tornado
was located over Gilliam, or 23 miles northwest of Bossier City,
moving east at 15 mph.

HAZARD...Tornado and ping pong ball size hail. 

SOURCE...Radar indicated rotation. 

IMPACT...Flying debris will be dangerous to those caught without 
         shelter. Mobile homes will be damaged or destroyed. Damage 
         to roofs, windows, and vehicles will occur.  Tree damage is 
         likely. 

This dangerous storm will be near...
  Belcher around 840 PM CDT. 
  Gilliam around 845 PM CDT. 

Other locations impacted by this tornadic thunderstorm include Alden
Bridge and Cavett.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

TAKE COVER NOW! Move to a basement or an interior room on the lowest
floor of a sturdy building. Avoid windows. If you are outdoors, in a
mobile home, or in a vehicle, move to the closest substantial shelter
and protect yourself from flying debris.

Heavy rainfall may hide this tornado. Do not wait to see or hear the
tornado. TAKE COVER NOW!

&&

LAT...LON 3273 9392 3279 9399 3291 9381 3275 9369
TIME...MOT...LOC 0132Z 264DEG 14KT 3280 9388 

TORNADO...RADAR INDICATED
HAIL...1.50IN

$$

13

The office that day

Everything else NWS Shreveport, LA issued on the same UTC day.

Issued	Product	Office	Counties	Lasted
May 11, 8:11 PM CDT	Severe Thunderstorm Warning	SHV	Bossier, Caddo	64 min
May 11, 8:52 PM CDT	Tornado Warning	SHV	Bossier, Webster	18 min
May 11, 9:17 PM CDT	Severe Thunderstorm Warning	SHV	De Soto, Sabine	43 min
May 12, 4:32 AM CDT	Lake Wind Advisory	SHV	Bossier, Caddo, De Soto, Sabine	13 hr

Nearby

Tornado Warnings in Louisiana, 2017 Every tornado warning in 2017 Tornadoes 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; local storm reports from the same archive; the sounding from the Mesonet's radiosonde archive; radar from the NEXRAD Level II archive.