|Severe Weather Awareness
NWS La Crosse
Tornado and Severe Weather Awareness Week is coming! In cooperation with state emergency management agencies, the National Weather Service (NWS) uses this week to remind people about the dangers of severe weather, including thunderstorms, flash flooding, and tornadoes. It is important you know what to do when severe weather strikes. A Tornado Drill is also done during the week in order to test warning dissemination methods and communication.
|STATE||DATE||Tornado Drill Day|
|National||March 2-8, 2014||No National Drill|
|Iowa||March 24-28, 2014||March 26 (10:20 a.m.) - Using live TOR EAS Code|
|Minnesota||April 21-25, 2014||April 24 (1:45 p.m. and 6:55 p.m.) - Using live TOR EAS Code|
|Wisconsin||April 21-25, 2014||April 24 (1:45 p.m.) - Using live TOR EAS Code|
A variety of topics will be covered during each week, including:
Contact Todd Shea, Warning Coordination Meteorologist, for an interview or additional information.
Hazardous Weather Outlook (HWO)
Severe Thunderstorm Watch
Flash Flood Watch
Severe Thunderstorm Warning (SVR)
Flash Flood Warning (FFW)
Tornado Warning (TOR)
A thunderstorm is defined as severe if it produces damaging wind gusts (58 mph or higher), large hail (one inch or larger in diameter), a tornado, or a combination of these elements. Of course thunderstorms also produce deadly lightning and heavy rains. Most thunderstorms do not become severe, but for the smaller percentage that do - Severe Thunderstorm Warnings are issued.
Severe thunderstorms can occur at any time of the year, day or night. The peak season for thunderstorms is from April through September, and during the afternoon or evening hours.
The most common type of severe weather is damaging thunderstorm wind, also known as "straight line wind". Strong thunderstorm wind gusts can reach hurricane force and in extreme cases - 100+ mph. Wind damage can be extensive and affect entire counties instead of narrow tracks like tornadoes. Objects like branches, trees, barns, outbuildings, high-profile vehicles, and power lines/poles can be toppled or destroyed, but as wind gusts increase you can have damage to roofs, windows, or homes. Some extreme examples from June 1998 include entire homes destroyed in Nashua, IA or swaths of flattened trees in western Wisconsin.
Large hail is also common and can produce tremendous property damage. Usually large hail does not become life threatening unless people are stuck outdoors without shelter. Hail is considered severe when it reaches the size of a quarter or larger. Baseball size hail fell at the La Crosse NWS office in June 2001.
Have a good source of weather information. When a severe thunderstorm moves into your area, or a warning is issued for your county, take action to protect yourself and property:
For a full link to Flood Safety, click here.
Flash flooding, one of the leading thunderstorm killers, is a rapid rise in small creeks or streams, usually from excessive thunderstorm rains. Flash flooding can also occur with ice jams on rivers or if a dam fails. A mudslide, like what hit Cassville, WI in 2002, can also indicate flash flooding and can be just as dangerous.
How bad can flash flooding be? This question was answered in August of 2007 when over a foot of rainfall hit parts of southeast Minnesota and southwest Wisconsin. Flash flooding was significant. There were eight fatalities directly related to the flash flooding (7 of them involved automobiles). Property damage was tremendous and terrain was changed. Even though scientists feel this may have been a 1-in-2000 year flood, lessons learned from this flash flood will not soon be forgotten by those impacted.
In 2004, there were two deaths in our area from flooding. One was in Vernon Co., WI when a woman drove into a flash flood late at night - click here to see this summary. The second case was from the river flooding in Austin, MN when days of heavy rain caused the Cedar River to overflow and a 20-year old man tried to cross it on foot.
Most people don't respect or understand the force of flowing water. Many automobiles become bouyant in as little as 2 feet of water, and you can lose control of your vehicle in as little as 6 inches. Even pickup trucks or SUVs may begin to float in relatively shallow water given the size of the tire. Most flash flood related deaths occur from people driving into high water. This is especially dangerous at night when people may not see the flooding and simply drive into it.
When flash flooding is observed, or a warning is issued for your county, take action to protect yourself and property:
A tornado is a violently rotating column of air in contact with the ground. The peak tornado months are May and June (July is 3rd), but tornadoes can occur any time of year if conditions are right. Peak tornado time is 3:00 to 9:00 PM, but they can occur day or night, and may be hard to spot or wrapped in rain at times. Tornadoes are not always visible and can form with little advance warning.
While larger tornadoes are somewhat rare in the region, we have had several in the last 6 years. An F3 tornado hit the Iowa-Minnesota state line on June 11, 2004. We've had two F2 tornadoes in our area since 1997 include Lewiston, MN (Winona County) in 1999, and Gilman, WI (Taylor County) in 2002.
Have a good source of weather information. Consider NOAA Weather Radio. If a tornado or funnel cloud is spotted, or a warning is issued for your county, take action to protect yourself.
Minnesota Tornado Outbreaks
1. June 16, 1992: 27 tornadoes
2. July 1, 1997: 18 tornadoes
3. June 11, 2001: 16 tornadoes
3. June 13, 2001: 16 tornadoes
5. June 28, 1979: 15 tornadoes
5. June 24, 2003: 15 tornadoes
7. July 21, 1995: 14 tornadoes
7. October 26, 1996: 14 tornadoes
7. March 29, 1998: 14 tornadoes
7. July 25, 2000: 14 tornadoes
Wisconsin Tornado Outbreaks
1. August 18, 2005: 27 tornadoes
2. May 8, 1988: 24 tornadoes
3. July 3, 1983: 22 tornadoes
4. June 8, 1993: 18 tornadoes
5. June 23, 2004: 17 tornadoes
Lightning is also a top killer. On average, 55 people in the U.S. are killed by lightning each year (30-year avg.). Like flash flooding, people do not respect lightning and will often dangerously continue outdoor activities as thunderstorms approach. Lightning is common to all thunderstorms so the threat is always there, with or without a severe weather warning. It only takes one lightning strike to kill or injure. Do not take chances!
You do not have to be directly under the storm, or where the heaviest rain is falling to get struck. Lightning strikes can occur many miles away from the parent thunderstorm. If you are near a storm or hear thunder, you are potentially close enough to get struck.
For additional Lightning Safety guidelines, click here.
With lightning in the area:
Staying informed of hazardous and life threatening weather is key to severe weather survival. NOAA Weather Radio is an excellent source of weather information directly from the National Weather Service.
Every school should have and monitor a NOAA Weather Radio!
NOAA Weather Radio broadcasts 24 hours a day - 7 days a week. At the touch of a button you can hear the:
To visit our main NOAA Weather Radio page, click here.
The National Weather Service in La Crosse currently operates 9 transmitters. (Soon to be 10!)
|Rochester, MN||WXK41||162.475 MHz|
|La Crosse, WI
|Black River Falls, WI||WNG564||162.500 MHz|
|Prairie du Chien, WI
Richland Center, WI
|Withee, WI||KZZ77||162.425 MHz|
|Ridgeville, WI (Tomah)||KE2XKP||162.525 MHz|
Ever wonder how accurate severe weather warnings are?
For local tornado and severe weather climatology: