The two maps below break up the US into National Weather Service forecast zones (areas each office is responsible for). It shows how many severe thunderstorm warnings and tornado warnings have been issued so far this year.
Here is a map showing the number of days, since October 1, 2005, that a state has had a Winter Storm and/or Blizzard Warning with a Tornado Watch at the same time in parts of the state.
Notice Iowa has had 3 days with this happening. One of those days was this last Wednesday, March 23rd when northern Iowa had Winter Storm Warnings in place at the same time southwest Iowa had a Tornado Watch.
10:00 AM – Test Tornado Watch issued for Iowa. The test watch will tone alert on NOAA All Hazards Radio.
10:10 AM – NWS Sioux Falls and Omaha issue test tornado warnings for their Iowa counties.
10:15 AM – NWS Des Moines and Quad Cities issue test tornado warnings for their Iowa counties. The test warning will alert on NOAA Weather radio.
10:20 AM – NWS La Crosse issues test tornado warning for their Iowa counties.
10:30-10:35 AM – All Iowa NWS offices issues a Severe Weather Statement to terminate the test warnings.
11:00 AM – Test tornado watch expires.
The average number of tornadoes across Iowa, in a year, is 48. Last year there were 58 tornadoes reported. Almost half of the 58 were reported during the last three months of the year (see chart below). Most of the tornadoes we get are in the spring.
Tornadoes usually occur during the afternoon and evening hours when the atmosphere is the most unstable. Last year was no exception when 78% of the tornadoes occurred between 2PM and 7 PM.
If you look back to last year, there were no tornado watches issued for a few counties in northeast Iowa.
Here is another interesting chart for northeast Iowa, particularly for Allamakee County. The last time any part of Allamakee County was under a Tornado Warning was 2009.
Do you know what to do if you are the path of a storm producing severe weather? You should, and you should have a plan of action. Knowing what to do before hand is very important. So important, it will most likely will save your life.
KNOW YOUR RISK
HAVE A PLAN
Everyone should know where to go either at home, work and/or school if a warning is issued for your location. Take a look at this video below. It will help you with your plan.
Here is the Ready.gov link mentioned in the video above.
After you have a plan…PRACTICE it. Go through the motions so you don’t have to think about what to do. You might not have enough time to think about what to do. During days of potential severe weather, you should be aware of your weather surroundings. Some days a sunny afternoon can quickly turn into a dangerous situation.
Now that we know the difference between a watch and warning, how do you get this information so that you can take action? There are many ways to get this information. TV
KWWL is staffed 24 hours a day when there is a risk for strong or severe storms. We are constantly tracking the potential for any severe weather. Any time a warning is issued, day or night, we will break into programming. We will have continuous coverage when a tornado warning is issued. We also will have a map and crawl on the screen until the warning is over. RADIO
Pick your favorite radio station. NOAA WEATHER RADIO
It is a great tool for when you are sleeping and severe weather is heading in your direction. Here is link for the information to program your weather radio.
http://www.nws.noaa.gov/nwr/coverage/ccov.php?State=IA OUTDOOR WARNING SIREN
When the siren goes off you should head inside and seek more information. The siren has different meanings. Some counties will sound the siren for tornadoes, while other will sound the siren for extreme damaging winds (70 mph or stronger) and tornadoes. The siren has and is only in place for those outside. It was never meant for warning people in buildings/homes. CELL PHONE/MOBILE DEVICES
You can sign up for KWWL text alerts. You will be alerted to any watches or warnings you have signed up for to your cell phone or mobile device. Here is the link to sign up. It is located on the right-hand side of the web page…just scroll down a little bit (near the 7 day forecast)
There is also the Wireless Emergency Alerts (WEA). This is automatically on your newer phones. The warnings we would get from this service in Iowa is a Tornado Warning and Flash Flood Warning.
Click on this link to learn more about his service. http://www.nws.noaa.gov/com/weatherreadynation/wea.html INTERNET
As soon as any weather alert is issued from the National Weather Service, the alert will be scrolling across the top our web page at KWWL.com. Just click on the county you are interested in and it will give you more information.
OK, so now you have many ways to get weather alerts and take appropriate action.
The week of March 21 through March 25 has been designated as Severe Weather Awareness Week by Iowa Governor Terry Branstad. Each day this week a different severe weather topic will be covered. The idea is to get people thinking about severe weather again. We will also try and teach you a few tidbits about weather as well.
Today we will discuss Severe Thunderstorms. First let’s take a look at what the difference is between a WATCH and a WARNING. If you don’t know, don’t worry. I come across many people each year that don’t know the difference.
A Severe Thunderstorm WARNING would be issued if the storm is or about to produce either large hail (1” in diameter or larger) or strong winds (58 mph or stronger).
A WATCH is issued when weather conditions are favorable for severe weather during the next few hours. Typically the watches are issued for 6 hours for large sections of states or portions of a few states. When a WATCH is issued you should be aware of your weather surroundings and have a plan to take action if a WARNING was issued.
Now a WARNING means severe weather is occurring and take shelter NOW. The warning lasts between 20 minutes to as long as an hour for slow moving storms. They only cover portions of counties and give you only minutes advance notice to take shelter.
There are three things every thunderstorm needs:
-Moisture (this is needed to form clouds and then rain)
-Unstable Air (this is warm air that can rise quickly)
-A lifting mechanism (something to cause the warm air to lift…like a cold front or the sun’s heating of the day)
Thunderstorms are relatively small compared to hurricanes and winter storms. An average size storm has a diameter of 15 miles and only last about 30 minutes. Now keep in mind this is average. Some storms are much larger and last longer as well as the other direction…smaller and don’t last very long.
At any time, there are about 1,800 thunderstorms around the world….this adds up to about 16 million a year. Florida has the most thunderstorms, per year, in the nation. The map below shows the average number of days each year thunderstorms occur.