Alert archive / Louisiana / Severe Thunderstorm Warnings in 2012

Severe Thunderstorm Warning 49, NWS Shreveport, LA

March 20, 20124 parishes in Louisiana

NWS Shreveport, LA issued this severe thunderstorm warning at Mar 20, 2012, 12:30 PM CDT for 4 parishes in Louisiana. It was in force for 60 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: Mar 20, 2012, 12:30 PM CDT (17:30 UTC)
Expired: Mar 20, 2012, 1:30 PM CDT
In force: 60 min
Issued by: NWS Shreveport, LA
Area: Storm-based polygon

Counties Grant Parish, LA, Natchitoches Parish, LA, Sabine Parish, LA, Winn Parish, LA

What was reported inside it

Time	Report	Where	Remark
Mar 20, 12:30 PM CDT	TSTM WND DMG	Provencal, LA	TREES DOWN ON HWY 117 NEAR PROVENCAL

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
Mar 20, 9:46 AM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 5.5 hours before the alert went out and 140 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: 395 J/kg
Mixed-layer CIN: -45 J/kg
Mixed-layer LCL: 754 m above ground
0-6 km bulk shear: 40 kt
0-1 km storm-relative helicity: 221 m²/s²
0-3 km storm-relative helicity: 306 m²/s²
Significant tornado parameter: 0.4
Supercell composite: 2.1

Open this sounding in Storm Lab

The text

As transmitted, in the capitals the NWS used until 2016.

992 
WUUS54 KSHV 201730
SVRSHV
LAC043-069-085-127-201830-
/O.NEW.KSHV.SV.W.0049.120320T1730Z-120320T1830Z/

BULLETIN - EAS ACTIVATION REQUESTED
SEVERE THUNDERSTORM WARNING
NATIONAL WEATHER SERVICE SHREVEPORT LA
1230 PM CDT TUE MAR 20 2012

THE NATIONAL WEATHER SERVICE IN SHREVEPORT HAS ISSUED A

* SEVERE THUNDERSTORM WARNING FOR...
  GRANT PARISH IN NORTH CENTRAL LOUISIANA...
  SOUTHERN WINN PARISH IN NORTH CENTRAL LOUISIANA...
  THIS INCLUDES THE CITY OF WINNFIELD...
  SOUTHERN NATCHITOCHES PARISH IN NORTHWEST LOUISIANA...
  THIS INCLUDES THE CITY OF NATCHITOCHES...
  EAST CENTRAL SABINE PARISH IN NORTHWEST LOUISIANA...

* UNTIL 130 PM CDT

* AT 1225 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED A
  LINE OF SEVERE THUNDERSTORMS CAPABLE OF PRODUCING DESTRUCTIVE WINDS
  IN EXCESS OF 70 MPH.  THESE STORMS WERE LOCATED ALONG A LINE
  EXTENDING FROM NATCHITOCHES TO 30 MILES SOUTHWEST OF MONTGOMERY...
  OR ALONG A LINE EXTENDING FROM NATCHITOCHES TO 6 MILES NORTH OF
  SLAGLE...AND MOVING EAST AT 40 MPH.

* OTHER LOCATIONS IN THE WARNING INCLUDE BUT ARE NOT LIMITED TO
  COLFAX...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A TORNADO WATCH REMAINS IN EFFECT FOR THE WARNED AREA. IF A TORNADO
IS SPOTTED... ACT QUICKLY AND MOVE TO A PLACE OF SAFETY IN A STURDY
STRUCTURE...SUCH AS A BASEMENT OR SMALL INTERIOR ROOM.

THIS STORM HAS A HISTORY OF PRODUCING WIDESPREAD WIND DAMAGE ACROSS 
FLORIENE. THIS IS AN EXTREMELY DANGEROUS SITUATION. SEEK SHELTER NOW 
INSIDE A STURDY STRUCTURE AND STAY AWAY FROM WINDOWS!

&&

LAT...LON 3136 9303 3136 9334 3173 9329 3202 9231
      3196 9231 3144 9245 3138 9266 3140 9270
      3144 9269 3151 9272 3134 9295
TIME...MOT...LOC 1730Z 251DEG 33KT 3176 9304 3130 9308

$$

24

The office that day

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

Issued	Product	Office	Counties	Lasted
Mar 19, 8:36 PM CDT	River Flood Warning	SHV	Caddo	6 days
Mar 20, 10:55 AM CDT	Tornado Warning	SHV	De Soto, Sabine	35 min
Mar 20, 11:06 AM CDT	River Flood Warning	SHV	Bossier, Webster	32 days
Mar 20, 11:16 AM CDT	River Flood Warning	SHV	Bienville, Bossier, Webster	12 days
Mar 20, 11:17 AM CDT	River Flood Warning	SHV	Lincoln, Ouachita, Union	7 days
Mar 20, 11:31 AM CDT	Tornado Warning	SHV	De Soto, Natchitoches, Sabine	29 min
Mar 20, 11:35 AM CDT	Severe Thunderstorm Warning	SHV	Natchitoches, Sabine	55 min
Mar 20, 12:10 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, De Soto, Natchitoches, Red River, Sabine	65 min
Mar 20, 12:54 PM CDT	Tornado Warning	SHV	Natchitoches, Winn	36 min
Mar 20, 1:04 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, Jackson, Lincoln, Natchitoches, Red River, Winn	41 min
Mar 20, 1:34 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, Grant, Jackson, Natchitoches, Winn	56 min
Mar 20, 3:03 PM CDT	Flash Flood Warning	SHV	Grant, Natchitoches, Winn	6 hr
Mar 20, 6:24 PM CDT	Flash Flood Warning	SHV	Natchitoches, Sabine	3 hr

Nearby

Severe Thunderstorm Warnings in Louisiana, 2012 Every severe thunderstorm warning in 2012

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.