Friday: Flooding and Flash Flooding

Severe Weather Awareness Week in Iowa ends today, but the important lessons continue. Today’s topics are Flooding and Flash Flooding.

There is a difference between “flooding” and “flash flooding”.  Both involve a lot of water, of course, where it shouldn’t be running.

Flooding usually occurs over a long stretch of time and can affect a very large area. The river floods of 1993 and 2008 are examples of “flooding”.

Flash floods are just as they sound… they happen in a flash! They typically occur over a relatively small area and can sometimes occur in a matter of minutes, and streams will usually be back within their banks within an hour or so.

Both are dangerous and should never be taken lightly.

If you were living in Iowa in 1993 or 2008, you remember the major flooding that occurred.

Downtown Cedar Rapids, 2008 photo taken by Iowa Civil Patrol

 

 

Coralville flooding in 2008- photo by U.S. Geological Survey

 

 

Union Pacific Railroad Bridge- photo Waterloo Courier via National Weather Service Des Moines

 

 

River flooding generally takes a lot of time to get to those levels. Saturated soil and heavy rainfall over many days will lead to flooding.

Flash flooding is much faster. In our area it is usually caused by a lot of rainfall in a short period of time. This causes rapid rises on creeks and streams which will then rush into rivers and work downstream in a sort of large wave of water.

 

 

It may only take 6 inches of fast-moving water to knock you off of your feet.

 

 

Never walk through flooded streets- manhole covers may no longer be there and you will drop under the water quickly.

Never drive through flooded roadways. As mentioned in the graphic above, it only takes a little bit of water to wash your car away. And, your road may no longer be there.

Highway 6 near the Cedar River at Atalissa, 2008- photo by Iowa Department of Transportation

 

 

 

 

 

 

 

 

Never drive around barriers. They are there for a reason. Be very careful driving at night.

 

 

To learn more about flood safety in Iowa, click here.  The National Weather Service also provides a lot of information here.

 

Share

Posted under Education, Flooding, Rivers, Severe Weather

This post was written by Schnack on March 30, 2018

Thursday: Family Preparedness

Today’s topic is FAMILY PREPAREDNESS. Nobody knows when a disaster will happen to you. Don’t have the …it won’t happen to me…attitude. If you are prepared the disaster will be easier to handle. You need to have a plan for you and your family. It is best to make a plan now and know what to do when severe approaches and what to do after the storm. HAVE A PLAN. These four steps can help you.

Step 1: Answer these questions…

1) How are we going to receive watches and warnings? (Check back to the Tuesday topic to help you with that information.)

2) Where will I take shelter?

3) Evacuation route?

4) What is the communication plan?

Step 2: What are the needs for each member of your house? Don’t forget your pets needs.

Step 3: Write out the plan on paper. This link will help you.

Step 4: Practice…go through the motions on what you will do and here you will go. Practice the plan.

This link has more details on the above steps.

 

Click on the image below to get a printable list of items you should have before a disaster occurs.

The three videos below are what you should do before, during and after a tornado in your area.

 

Share

Posted under Education, NOAA, Severe Weather, Video

This post was written by Schnack on March 29, 2018

Wednesday: Tornadoes

The topic today is all about tornadoes.

Earlier this morning tornado was a tornado drill. A test watch and warning were sent. This test was not going to activate the Wireless Emergency Alert (WES) messaging system on cell phones. 3rd party mobile and desktop applications varied in behavior and performance based upon coding within the application.

They are one of the most violent forms of weather we have here on Earth. They can destroy lives and livelihoods in a matter of seconds.

Let’s start with what is a tornado? The official definition from the National Severe Storms Laboratory is A tornado is a narrow, violently rotating column of air that extends from the base of a thunderstorm to the ground. Because wind is invisible, it is hard to see a tornado unless it forms a condensation funnel made up of water droplets, dust and debris. Tornadoes are the most violent of all atmospheric storms.

Tornadoes occur in many parts of the world. The United States has more tornadoes than any other part of the world. Argentina and Bangladesh are the next two countries with the highest concentration of tornadoes. The map below shows areas that are more favorable to see tornadoes.

Here in Iowa, tornadoes can occur any time of the year. Here is a chart showing the number of tornadoes for each month of the year from 1980-2016.  It shows zero for January and February, but before 1980 there were some in those months. June is the month with the most tornadoes followed behind with May. April and July are a distant 3rd and 4th.

Each year, about 1,200 tornadoes hit the United States. Official records have only been kept since 1950. There are a lot more storm chasers and public reports in the last 10-20 years observing them. This helps in keeping accurate tornado records. Iowa had 55  tornadoes in 2017, just above average.

Here is the break down in the EF-scale rating from the 2017 Iowa torandoes.

Most of the tornadoes were the weaker ones (EF0 and EF1)…this is typical. Not very often does Iowa or the rest of the U.S. see EF4 or EF5 tornados. Tornadoes are ranked on an EF Scale (Enhanced Fujita) based on the damage it has done.

The video below shows the birth of a tornado in May 2013 in Oklahoma.

 

The video below is a look behind the scenes at the Storm Prediction Center on the forecast process of a severe weather outbreak.

During tornado coverage you might hear terms you are unfamiliar with. Here are just a few you might hear. Hopefully we don’t have to talk about the first or third one in real-time.

Here is a link to commonly asked questions about tornadoes.

Another link with more facts and figures about tornadoes.

When there is chance of severe weather and tornadoes, you need to pay attention to your weather surroundings. Tornadoes can move as fast as 60 mph. On the other hand some move less than 5 mph. The average speed is 10-20 mph. Make sure you have a plan on what to do before severe weather threatens you. This will be the topic tomorrow. Severe weather preparedness.

Share

Posted under Education, Severe Weather

This post was written by Schnack on March 28, 2018

Tuesday: Receiving Warning Information

It’s Severe Weather Awareness Week in Iowa, and each day we are talking about an important topic to prepare for severe weather.  Today we look into receiving warning information.

First, it’s important to know the difference between a watch and warning.  Whether it be a severe thunderstorm, tornado or flash flood, a WATCH indicates conditions are favorable severe within the next few hours (up to 6, generally).  A WARNING means severe weather is imminent, and you need to take action immediately.

In order to get those warnings, you should have multiple ways of receiving severe weather alerts.

Of course, in the event of severe weather, KWWL will be first on the air to bring you the latest updates.  When a Severe Thunderstorm or Tornado Watch is in effect, we will have updates at least every half hour on TV.  Once a warning is issued, we will be on air immediately with the latest track and have important information to keep you safe.  Once a Tornado Warning is issued, KWWL will be wall-to-wall on KWWL 7.1, CW 7.2 and MeTV 7.3.  We will also be streaming live on the KWWL News App, as well as the KWWL Facebook page.

The watches and warnings will also scroll across the top of our website, KWWL.com, and will go directly to the KWWL Facebook and Storm Track 7 Facebook pages, as well as Storm Track 7 Twitter.

As you are probably aware, the Wireless Emergency Alerts on your phone will alert you, based on where you are located.  This is also the case with the FREE Storm Track 7 weather app.  Click here to learn more about the app, and download it today.

One of the best ways to keep you up-to-date on severe weather, is getting a NOAA Weather Radio.  They can generally be found at your local hardware store and some grocery stores.  Once you purchase it, you can program the radio to any county you want to receive warnings for, and for any weather event you want to be alerted about (severe thunderstorms, tornadoes, flash flooding, winter storm, etc.)

Here’s a video on how to program a NOAA Weather Radio.

Wednesday’s blog post will be all about tornadoes, and how common the are in Iowa.

Share

Posted under Education, Severe Weather

This post was written by Schnack on March 26, 2018

Monday: Severe Thunderstorms

Iowa Governor Kim Reynolds, Iowa Homeland Security and Emergency Management, and the National Weather Service have designated March 26 through March 30 as Severe Weather Awareness Week 2018. Each day, Monday through Friday, we will focus on one aspect of severe weather.

The first topic of the week is severe thunderstorms (of which there are none expected today). This is nothing new to Iowans. During the spring and summer months, we see numerous severe thunderstorm alerts. But first, how does a thunderstorm develop?

As mentioned in the video above, we are most likely to get severe weather when the storm is in its “mature” stage. For more information on thunderstorms, you can visit the NWS learning page here.

While all storms have the potential to cause damage, severe thunderstorms must meet certain criteria:

A storm must produce hail at least one inch in diameter and/or straight line winds of at least 58 mph. A thunderstorm that produces a tornado is considered severe but will cause a Tornado Warning to be issued. A high amount of lightning strikes is not a criteria for a Severe Thunderstorm Warning.

The National Weather Service office in Des Moines issued more than 200 Severe Thunderstorm Warnings in 2017.

The La Crosse, Wisconsin office issued 184 Severe Thunderstorm Warnings. There were 197 Severe Thunderstorm Warnings issued from the office in Davenport.

Severe Thunderstorm Warnings are the most frequently issued weather alert by the Des Moines weather service office.

The office issued at least 100 warnings per year for severe thunderstorms every year since 1996.

Most of the warnings come during the spring and summer months. Over the last 30 years, the bulk of the warnings are sent out during the months of May and June, with June seeing the most warnings from the Des Moines office. The graph below breaks down Severe Thunderstorm Warnings by week issued by the National Weather Service in Des Moines from 1986 – 2017. The top graph shows how many years at least one warning was issued during a particular week of the month. The bottom graph shows how many warnings were issued during each week of the year.

The National Weather Service is continuing to hold storm spotter training in eastern Iowa and southwest Wisconsin through early next week.

If you are interested in attending, it is free. However, if you either don’t live in those counties or unavailable at those times, there are online training sessions, as well. The La Crosse, Wisconsin office hosts their online webinars on April 6 (1:00pm – 3:00pm) and April 16 (7:00pm – 9:00pm). You can email todd.shea@noaa.gov for more information on accessing those sessions.

The Des Moines office hosts online training on April 4 (7:00 PM – 8:30pm) and April 18 (7:00pm – 8:30pm).
Go to: www.join.me/nws-desmoines
Dial: 1-866-231-8384 and enter 515-270-2614
iPhone/iPad and Android phone: Join.Me applications can be downloaded at www.join.me
Smartphone user access is: nws-desmoines
Contact Information: NWS Des Moines Phone: 515-270-2614

If you would like to watch a past storm spotter training, you can view a playlist by clicking here.

For more information on the storm spotter program, click here and choose your county.

The next blog will feature information on how to receive warning information.

Share

Posted under Education, Severe Weather

This post was written by Schnack on March 26, 2018

Rivers Visible

There is snow all over Iowa and with a clear sky this afternoon we have a great view of the rivers across the state.  Darker areas on the map are the rivers.

Share

Posted under Education, Rivers, Winter Weather

This post was written by Schnack on February 13, 2018

Evening Sounding

Here is a temp profile of the atmosphere this evening. At the ground it is cold, about 7° F and only about 5,000 ft up it warms to near 32° F

Share

Posted under Education

This post was written by Schnack on January 11, 2018

Sunglint

The new GOES-16 satellite is AMAZING. There are so many things we can see and so much more clear than the older satellites. This afternoon at the bottom of the image below you can see the sunglint.

Share

Posted under Education

This post was written by Schnack on March 30, 2017

Narrow snow band

Friday morning and into early afternoon, a narrow band of snow produced a few inches of snow in western Illinois. The snow developed similarly to the type of snow in areas around the Great Lakes. The first image below shows the band of snow just south of Davenport extending southeast.

KWWL 2015 MAX Storm ED

The visible satellite below shows the snow on the ground from today.

11

 

Andy Ervin, Senior Forecaster at the National Weather Service in Davenport, has more information about this type of situation. The paper below was originally written in 2006.

Click on the text below to enlarge.

9

 

 

Share

Posted under Education, Winter Weather

This post was written by Schnack on January 27, 2017

Precipitation Type

Here is a look at how the different precipitation types form. Way up in the sky the air is below freezing (below 32°F or 0°C). In some cases there is a warm layer closer to the ground. Exactly how thick that warm layer is and how close to the ground impacts the type of precipitation we receive.

I will start with snow (left side of the graphic below). As the snowflake above falls toward the ground, the temperature through out the travel toward the ground remains below freezing not allowing it to melt. So the snowflake stays a snowflake from top to bottom.

Now for sleet. The snowflake falls through a warm layer (above freezing) and the snow melts and turns to a raindrop. The raindrop than falls through a pretty thick layer of cold air. This allows the raindrop to freeze. By the time it reaches the ground it is sleet.

Compare that with freezing rain. That same warm layer is now thicker leaving a very small layer near the ground below freezing. There is less time for the raindrop to freeze and turn to sleet so it falls as rain and freezes on impact to anything on the ground.

Now if that layer is above freezing all the way to the ground it stays as rain and doesn’t freeze. The air closest to the ground is above freezing and the ground is above freezing. The result would be rain.

Precip Type

Share

Posted under Education, Educational, Ice, Winter Weather

This post was written by Schnack on January 12, 2017