Alert archive / Louisiana / Severe Thunderstorm Warnings in 2021

Severe Thunderstorm Warning 121, NWS Shreveport, LA

May 4, 2021Grant Parish, LaSalle Parish, Winn Parish, Louisiana

NWS Shreveport, LA issued this severe thunderstorm warning at May 4, 2021, 12:48 PM CDT for Grant Parish, LaSalle Parish, Winn Parish, Louisiana. It was in force for 57 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 4, 2021, 12:48 PM CDT (17:48 UTC)
Expired: May 4, 2021, 1:45 PM CDT
In force: 57 min
Issued by: NWS Shreveport, LA
Area: Storm-based polygon
Hail: 0.75 in
Wind: 60.0 mph

Counties Grant Parish, LA, LaSalle Parish, LA, Winn Parish, LA

The radar

The Ft Polk radar (KPOE), 58 km from the middle of the area, began a volume at 17:50 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 4, 12:50 PM CDT	TSTM WND DMG	6 Ssw Atlanta, LA	TREE DOWN ON HWY 471 NEAR THE GRANT PARISH LINE.

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 4, 10:52 AM CDT	Tornado Watch	SPC	7 hr

The nearest sounding before it

Shreveport, LA (KSHV), launched 12:00Z, 5.8 hours before the alert went out and 159 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: 2618 J/kg
Mixed-layer CIN: -96 J/kg
Mixed-layer LCL: 873 m above ground
0-6 km bulk shear: 44 kt
0-1 km storm-relative helicity: 208 m²/s²
0-3 km storm-relative helicity: 182 m²/s²
Significant tornado parameter: 1.3
Supercell composite: 6.0

Open this sounding in Storm Lab

The text

As transmitted.

745 
WUUS54 KSHV 041748
SVRSHV
LAC043-059-127-041845-
/O.NEW.KSHV.SV.W.0121.210504T1748Z-210504T1845Z/

BULLETIN - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Warning
National Weather Service Shreveport LA
1248 PM CDT Tue May 4 2021

The National Weather Service in Shreveport has issued a

* Severe Thunderstorm Warning for...
  Grant Parish in north central Louisiana...
  La Salle Parish in north central Louisiana...
  Southern Winn Parish in north central Louisiana...

* Until 145 PM CDT.

* At 1247 PM CDT, a severe thunderstorm was located over Colfax, or 7
  miles northeast of Lena, moving east at 40 mph.

  HAZARD...60 mph wind gusts.

  SOURCE...Radar indicated.

  IMPACT...Expect damage to roofs, siding, and trees.

* Locations impacted include...
  Jena, Colfax, Montgomery, Midway, Pollock, Dry Prong, Tullos,
  Georgetown, Atlanta, Nebo, Rogers, Catahoula Lake, Bentley,
  Rochelle, Zenoria, Lake Iatt, Fishville, Williana, St. Maurice and
  Aloha.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Tornado Watch remains in effect until 600 PM CDT for north central
and northwestern Louisiana.

For your protection move to an interior room on the lowest floor of a
building.

Torrential rainfall is occurring with this storm, and may lead to
flash flooding. Do not drive your vehicle through flooded roadways.

&&

LAT...LON 3133 9201 3134 9204 3132 9208 3135 9208
      3141 9215 3148 9218 3139 9266 3141 9267
      3140 9269 3145 9268 3145 9270 3147 9269
      3152 9272 3160 9280 3162 9290 3168 9293
      3168 9297 3177 9297 3182 9294 3181 9200
TIME...MOT...LOC 1747Z 269DEG 33KT 3154 9270 

HAIL...<.75IN
WIND...60MPH
 
$$

05

The office that day

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

Issued	Product	Office	Counties	Lasted
May 4, 10:44 AM CDT	Special Weather Statement	SHV	Bossier, Caddo	46 min
May 4, 10:54 AM CDT	Special Weather Statement	SHV	Caddo	66 min
May 4, 11:07 AM CDT	Severe Thunderstorm Warning	SHV	De Soto	38 min
May 4, 11:10 AM CDT	Severe Thunderstorm Warning	SHV	Bienville, Bossier, Caddo, De Soto, Webster	50 min
May 4, 11:14 AM CDT	Severe Thunderstorm Warning	SHV	Bossier, Caddo, De Soto	31 min
May 4, 11:24 AM CDT	Severe Thunderstorm Warning	SHV	Bienville, Claiborne, Jackson, Lincoln	51 min
May 4, 11:45 AM CDT	Special Weather Statement	SHV	Natchitoches	45 min
May 4, 11:48 AM CDT	Special Weather Statement	SHV	Ouachita	42 min
May 4, 12:05 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, De Soto, Natchitoches, Red River, Sabine	40 min
May 4, 12:17 PM CDT	Severe Thunderstorm Warning	SHV	Natchitoches, Sabine	43 min
May 4, 12:25 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, Jackson, Lincoln, Ouachita, Union	65 min
May 4, 12:28 PM CDT	Severe Thunderstorm Warning	SHV	Caldwell, Jackson, Ouachita, Union, Winn	47 min
May 4, 12:41 PM CDT	Severe Thunderstorm Warning	SHV	Bienville, Jackson, Natchitoches, Winn	64 min
May 4, 12:53 PM CDT	Severe Thunderstorm Warning	SHV	Caldwell, Jackson, LaSalle	52 min

Nearby

Severe Thunderstorm Warnings in Louisiana, 2021 Every severe thunderstorm warning in 2021

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.