Alert archive / Montana / Tornado Warnings
Tornado Warnings in Montana, 2013
25 tornado warnings in 2013. An alert counts here when it covered any part of the state, so the counties below add up to more than the state. The archive of tornado warnings reaches back to 1986.
Tornado Warnings by county
Each county as a circle sized by its count in 2013. Tap one for its archive.
- Tornado Warnings
- 25
- Busiest month
- May10 tornado warnings
- Busiest day
- May 27, 20135 tornado warnings
Over time
By month
Warning verification
How often warnings here had a storm report inside them, and how much warning the reports had.
6 of 25 tornado warnings covering Montana in 2013 had a tornado report inside them; 7 of 11 tornado reports fell inside a warning, on average 11 minutes after it went out.
Montana, 2013
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| Tornado warnings | 25 | 6 | 76% | 11 | 64% | 11 min |
Each office's whole area, 2013
| Warnings | With a report | False alarm ratio | Reports | Inside a warning | Mean lead time | |
|---|---|---|---|---|---|---|
| NWS Great Falls, MT: tornado warnings | 2 | 0 | 100% | 0 | ||
| NWS Glasgow, MT: tornado warnings | 8 | 4 | 50% | 5 | 100% | 12 min |
| NWS Missoula, MT: tornado warnings | 0 | 1 | 0% | |||
| NWS Billings, MT: tornado warnings | 15 | 2 | 87% | 5 | 40% | 7 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
Every alert, in the order issued. Times are local, Mountain Time. Each opens its own page with the text, the map, the radar and the sounding.
| Issued | Product | Office | Counties | Lasted |
|---|---|---|---|---|
| May 25, 4:07 PM MDT | Tornado Warning | BYZ | Carter | 23 min |
| May 25, 4:29 PM MDT | Tornado Warning | BYZ | Carter | 31 min |
| May 25, 5:00 PM MDT | Tornado Warning | BYZ | Carter | 30 min |
| May 25, 6:46 PM MDT | Tornado Warning | BYZ | Carter | 29 min |
| May 25, 7:13 PM MDT | Tornado Warning | BYZ | Carter | 32 min |
| May 26, 6:39 PM MDT | Tornado Warning | BYZ | Powder River | 51 min |
| May 26, 6:45 PM MDT | Tornado Warning | BYZ | Musselshell, Rosebud, Treasure, Yellowstone | 45 min |
| May 26, 8:50 PM MDT | Tornado Warning | BYZ | Treasure, Yellowstone | 40 min |
| May 26, 8:59 PM MDT | Tornado Warning | BYZ | Rosebud | 31 min |
| May 26, 9:31 PM MDT | Tornado Warning | BYZ | Rosebud, Treasure | 44 min |
| Jun 13, 5:30 PM MDT | Tornado Warning | BYZ | Golden Valley, Stillwater, Sweet Grass | 45 min |
| Jun 19, 3:15 PM MDT | Tornado Warning | TFX | Broadwater, Gallatin, Meagher | 30 min |
| Jun 22, 1:25 PM MDT | Tornado Warning | BYZ | Golden Valley, Stillwater | 35 min |
| Jul 8, 2:40 PM MDT | Tornado Warning | TFX | Fergus | 35 min |
| Jul 8, 5:21 PM MDT | Tornado Warning | BYZ | Rosebud, Treasure | 24 min |
| Jul 15, 3:45 PM MDT | Tornado Warning | GGW | Roosevelt | 30 min |
| Jul 15, 3:58 PM MDT | Tornado Warning | GGW | Roosevelt | 32 min |
| Jul 15, 4:25 PM MDT | Tornado Warning | GGW | Roosevelt | 35 min |
| Jul 15, 4:53 PM MDT | Tornado Warning | GGW | Roosevelt | 37 min |
| Jul 20, 6:57 PM MDT | Tornado Warning | GGW | Dawson, McCone | 33 min |
| Jul 20, 7:25 PM MDT | Tornado Warning | GGW | Dawson | 35 min |
| Jul 20, 7:43 PM MDT | Tornado Warning | GGW | Dawson | 32 min |
| Jul 20, 8:29 PM MDT | Tornado Warning | GGW | Dawson, Prairie | 31 min |
| Aug 3, 7:23 PM MDT | Tornado Warning | BYZ | Powder River | 22 min |
| Aug 3, 7:44 PM MDT | Tornado Warning | BYZ | Powder River | 31 min |
By county
Every county with at least one alert. A county page lists each alert that covered it.
The busiest days
Days with the most alerts issued, by UTC date.
Nearby
Alerts in force nowTornadoes on recordThe radar archive20122014
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.