Weather alerts in Louisiana, 2020
3,718 weather alerts in 2020, from the National Weather Service and the Storm Prediction Center. An alert counts here when it covered any part of the state, so the counties below add up to more than the state.
Weather alerts by county
Each county as a circle sized by its count in 2020. Tap one for its archive.
- Alerts
- 3,718
- Warnings
- 1,581
- Watches
- 123
- Advisories
- 515
- Busiest month
- April615 alerts
- Busiest day
- April 19, 2020102 alerts
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
28 of 188 tornado warnings covering Louisiana in 2020 had a tornado report inside them; 47 of 77 tornado reports fell inside a warning, on average 16 minutes after it went out.
Louisiana, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 188 | 28 | 85% | 77 | 61% | 16 min |
| Severe thunderstorm warnings | 384 | 192 | 50% | 463 | 73% | 24 min |
| Flash flood warnings | 93 | 53 | 43% | 139 | 82% | 123 min |
Each office's whole area, 2020
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Jackson, MS: tornado warnings | 60 | 37 | 38% | 149 | 85% | 26 min |
| NWS Jackson, MS: severe thunderstorm warnings | 423 | 268 | 37% | 898 | 83% | 26 min |
| NWS Jackson, MS: flash flood warnings | 108 | 73 | 32% | 276 | 85% | 87 min |
| NWS Lake Charles, LA: tornado warnings | 91 | 10 | 89% | 37 | 49% | 13 min |
| NWS Lake Charles, LA: severe thunderstorm warnings | 119 | 40 | 66% | 121 | 60% | 21 min |
| NWS Lake Charles, LA: flash flood warnings | 44 | 14 | 68% | 46 | 87% | 172 min |
| NWS New Orleans, LA: tornado warnings | 99 | 10 | 90% | 37 | 49% | 10 min |
| NWS New Orleans, LA: severe thunderstorm warnings | 133 | 30 | 77% | 123 | 49% | 17 min |
| NWS New Orleans, LA: flash flood warnings | 30 | 11 | 63% | 27 | 70% | 77 min |
| NWS Shreveport, LA: tornado warnings | 77 | 29 | 62% | 67 | 63% | 14 min |
| NWS Shreveport, LA: severe thunderstorm warnings | 252 | 186 | 26% | 540 | 79% | 24 min |
| NWS Shreveport, LA: flash flood warnings | 55 | 37 | 33% | 117 | 90% | 105 min |
An office's figures cover every county it serves, including across state lines.
Verified by the Iowa Environmental Mesonet's Cow, which matches each storm-based warning with the local storm reports inside its polygon while it was in force, within 15 km of its edge: a tornado warning counts as verified on a tornado report, a severe thunderstorm warning on hail of 1 inch or more, a gust of 58 mph or more, or wind damage, a flash flood warning on a flash flood report. The false alarm ratio is the share of warnings with no such report; "inside a warning" is the probability of detection, the share of reports that fell inside one; lead time runs from the warning's issue to each report inside it, counting zero for a report that came first. A warning with no report is not proof nothing happened: reports come from spotters, the public and damage surveys, and are thin where few people live.
The alerts
3,718 alerts are too many to list on one page. Narrow it to a product above, to a month in the chart, or to a county.
By product
Every kind of product issued here, grouped by hazard. Each opens the same place narrowed to that product.
By county
Every county with at least one alert. A county page lists each alert that covered it.
- East Baton Rouge Parish213
- Caddo Parish200
- Cameron Parish199
- Bossier Parish195
- Rapides Parish192
- Allen Parish192
- Washington Parish192
- Saint Helena Parish190
- Natchitoches Parish189
- Beauregard Parish188
- Vernon Parish186
- Saint John the Baptist Parish181
- Calcasieu Parish179
- Tangipahoa Parish176
- Evangeline Parish175
- Saint Martin Parish175
- East Feliciana Parish174
- Sabine Parish170
- Iberville Parish170
- West Baton Rouge Parish168
- De Soto Parish168
- Lafayette Parish166
- Saint Tammany Parish166
- Saint James Parish165
- Bienville Parish163
- Winn Parish162
- Saint Landry Parish160
- Webster Parish157
- Saint Bernard Parish156
- West Feliciana Parish154
- Pointe Coupee Parish153
- Grant Parish153
- Red River Parish151
- Assumption Parish149
- Jefferson Davis Parish144
- Orleans Parish143
- Avoyelles Parish142
- Saint Charles Parish140
- LaSalle Parish140
- Caldwell Parish137
24 more counties
- Jefferson Parish133
- Livingston Parish132
- Acadia Parish127
- Ouachita Parish126
- Concordia Parish123
- Tensas Parish123
- Jackson Parish122
- Madison Parish121
- East Carroll Parish119
- Franklin Parish118
- Union Parish117
- Claiborne Parish117
- Vermilion Parish116
- Lincoln Parish116
- Ascension Parish115
- Catahoula Parish109
- Richland Parish107
- West Carroll Parish107
- Morehouse Parish104
- Lafourche Parish100
- Iberia Parish73
- Plaquemines Parish73
- St. Mary Parish69
- Terrebonne Parish61
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20192021
Sources
National Weather Service watches, warnings, advisories and statements from the Iowa Environmental Mesonet's VTEC archive, which reconstructs tornado, severe thunderstorm, flash flood and marine warnings back to 1986 from the NWS text archive. Storm Prediction Center watches and mesoscale discussions from SPC's archive through the Mesonet. County centers from the US Census Bureau. Warning verification from the Mesonet's Cow. Rebuilt daily.