Monday, April 15, 2013

Minnesota Severe Weather Awareness Week 2013

This week is Severe Weather Awareness Week in Minnesota.  While we have been plagued by snow and cold lately, now is a good time to prepare for severe thunderstorms as we head towards the summer months.  On Thursday, there will be a statewide afternoon and evening tornado drill at 1:45 and 6:55 p.m., respectively.

An understanding of basic terminology is fundamental for severe weather safety.  Here are some terms you will see in the media, from the National Weather Service, and on this blog:

The Storm Prediction Center issues an outlook leading up to when dangerous weather is likely.  These outlooks may be issued as far out as eight days prior to the event.  For a better understanding of these outlooks, this post does an excellent job explaining the Storm Prediction Center products in-depth.

When conditions become favorable for organized severe thunderstorms and/or tornadoes to develop, a watch is issued by the Storm Prediction Center.  It means weather conditions are favorable for dangerous weather to occur. In other words, a "watch" means watch out for what the weather could do, and be ready to act accordingly. You may wish to alter or have a back-up plan for any outdoor activities or travel.  A typical watch duration is six to seven hours, but it may be cancelled, replaced, or re-issued as required.

A warning is issued by the local National Weather Service office when the weather event is imminent or occurring somewhere in the defined warning area, and that people need to take shelter as soon as possible.  These warnings can last as long as 45 minutes to an hour.  New to 2013 is the use of “impact based warnings” by the National Weather Service to emphasize threat and impacts to improve public response.  More information can be found in the video below:

Do you have enough “safety nets” in place for receiving these weather alerts?  Every person should have multiple means other than the outdoor warning sirens for being aware of approaching severe weather.  As I have stated many times before, sirens are only meant to be heard OUTDOORS as a means to get inside a sturdy structure when sirens are sounded.  In addition to the outdoor siren, conventional NOAA Weather Radio should be in every home, much like smoke detectors.  These radios can be set to alert you in standby mode to all or certain hazards within a county or counties, especially during hours of sleep.  It also provides general weather information 24 hours a day, seven days a week.

Many cell phones now feature the ability to receive Wireless Emergency Alerts (WEA), which allow push notifications when the user is within range of an affected hazard area. There are still compatibility issues with this system, mainly with AT&T’s new high-speed LTE network, so I can not recommend this system at this time until it works with all of the phones on the market.  For those who are unable to benefit from WEA, here are a couple apps which work nicely:

I personally prefer iMap Weather Radio as it allows selectable alerts from virtually every weather hazard possible.  Another benefit is that it uses GPS tracking to only alert when the phone is within the watch, warning, or advisory boundaries, unlike NOAA Weather Radio, which is currently limited to entire counties.  This app also features basic radar and Storm Prediction Center outlooks.  For $9.99, it is a bargain in my opinion considering the cost of weather radios run $30 or more.

Some tornado statistics.  From 1950 to 2010, Minnesota averaged 27 tornadoes a year.  Over 75% of the tornadoes during that period occurred in the months of May, June, and July.  The majority of tornadoes happen between 4 and 6 p.m.  When it comes to tornado intensity, Minnesota tornadoes tend to be on the low-end, with more than half being F/EF-0 and F/EF-1 strength.  The last F/EF-5 tornado in the state was in June 1992, affecting the southwestern town of Chandler.  An Enhanced Fujita scale table is found here.

If you have any severe weather or safety questions, please post them below!


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