Category Archives: Hazards and Threats

Weather Wednesday – First Tornado Captured by Radar

62 years ago this month, April 9, 1953, about 3 miles from where I am sitting, a tornado was caught by radar for the first time. Scientists and electrical engineers at the Illinois State Water Survey at the University of Illinois at Urbana-Champaign had modified a former WWII airborne radar for use in estimating amounts of precipitation falling from storms.

Don Staggs, an electrical engineer, was preparing the radar for later field tests. He started to notice what we now call “hook echo” returns in the scans of the storm. As afternoon turned to evening, a strong thunderstorm developed just north of Champaign, about ten miles from the radar site at the university-owned Willard Airport. The storm image included a pronounced hook on the bottom rear flank much as we see hook echoes on modern Doppler radar.

first radar image of a tornado
Illinois State Water Survey via The News Gazette

Still photos and a 16mm film of the images on the scope captured that moment. A team of meteorologists and technicians were able to study the image capture. Later, Dr. Ted Fujita the creator of the tornado strength measurement scale that bears his name, sketched over 200 of the frames of the film in his own hand. All of this can be seen in a terrific article from Colorado State University.  Note especially the photos of the tornado and the well-developed wall cloud.

We now know that the radar captured the early stages of an F3 tornado that eventually traveled about 160 miles and dissipated near Albany, IN. There were two fatalities and about $4-million in property damage in Illinois. The path of the storm took it across mostly rural areas.

Next week, we’ll discuss current use of radar and what may be the next generation of this important forecast tool.

Weather Wednesday — April 9, 2015 Illinois Tornado Outbreak

On this Tax Day edition of Weather Wednesday, we’ll revisit last week’s tornado outbreak in Illinois. Statewide, 11 tornadoes have been confirmed in the April 9th event. The earliest, which caused very little damage, was reported just northwest of Peoria in the afternoon hours. By early evening, strong thunderstorms were crossing far northern Illinois and eventually spawned the first EF-4 tornadoes ever reported in DeKalb and Ogle Counties (records kept since 1950) and the strongest tornado in the National Weather Service Chicago Office County Warning Area since an EF-5 devastated Plainfield, in the southwest suburbs, in 1990.

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AP

Two people were killed in the unincorporated town of Fairdale where nearly every structure, more than 70 in all counting outbuildings, was either damaged or destroyed. 22 injuries were reported in the outbreak. The tornadoes eventually approached the far western suburbs of Chicago but missed three population centers near their path. Damage was widely scattered in a multi-county area.

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PBrooks Photography

This outbreak was well forecast and there is general agreement there was plenty of warning. The Storm Prediction Center (SPC), as it did with the EF-3 and 4 tornadoes in Illinois on November 17, 2013, mentioned possibly tornadic storms at least four days in advance.

The National Weather Service Chicago Office updated their summary of the tornadoes just this morning. This is one of the most complete such documents I’ve ever read and includes some of the few satellite images of a tornado’s path I’ve ever seen. Read it all the way to the bottom and you’ll see the SPC guidance in the week leading up to the storms.

LarissaSebree_HillcrestIL
Wedge tornado and wall cloud near Hillcrest, Illinois. Larissa Sebree via NOAA.

A couple of these tornadoes were extremely well documented via video (note:  Strong language toward end) and live streaming and some of the visuals of the rotating wall clouds were just about textbook. The low sun angle contributed how well the tornadoes were captured.

There was also a significant side issue involving a motorist by the name of Sam Smith who was shooting video. That footage was widely shown on television and the driver was taken to task for getting too close to the storm, even if accidentally.  (There are now licensing issues with the video so we won’t link to it here.  However, it is widely available on You Tube.)

There were a couple of takeaways from his experience which are good reminders to all of us who may encounter storms. First, if a funnel cloud or tornado does not appear to be moving, it is either headed straight for the observer or dead away from the observer. To be safe, get out of that area immediately by driving at right angles to the storm. Second, this motorist backed up to take shelter in his vehicle under a bridge. Although many people have done that and survived, experts say that is a bad idea because wind speed may actually be amplified as it is compressed into that confined space.  There have been fatalities of people under overpasses.

Weather Wednesday –New Definitions from the Storm Prediction Center

There’s been much talk in recent weeks of a more detailed method of describing the potential for severe weather now being employed by the Storm Prediction Center in its Convective Outlooks. The SPC worked with National Weather Service offices, communications experts and consumers of its products to expand its long time use of the “Slight, Moderate and High” risk categories to “Marginal, Slight, Enhanced, Moderate and High.”

In addition, the chart below describes what the storms might look like under each newly-defined category and what the main threats would be.

Understanding Categories
The Storm Prediction Center has many products that can be used by broadcast meteorologists, emergency managers and the general public to look as far as 8 days ahead. These tools are especially valuable for planning purposes and should never supplant your detailed local forecast.

The Mesoscale Discussions are particularly helpful on days when severe weather is expected. The discussions are issued on an “as needed” basis as storm threats develop. Other tools are updated as often as four times a day. If you’ve never visited the site at spc.noaa.gov, now would be a good time to familiarize yourself with the offerings.

 

Weather Wednesday – Hail

On this April Fools Day, we’ll be discussing hail. Hail is widespread throughout the world, but doesn’t often have the top of mind awareness of other storm-related topics…unless, that is, you’re growing crops or insuring buildings or vehicles. According to the National Weather Service’s hail page, the average loss from hail each year is about a billion dollars. However, in 2001 there was one storm event that eventually stretched from Kansas City to Illinois that caused $2-billion damage on a single day.

Hail is not normally considered a major threat to human life. The last reported fatality in the United States was in 2000 when a Texas man died after being struck by a softball sized hail stone. Two children reportedly perished in Russia in 2014. Livestock losses are reported from time to time.

The National Weather Service rates hail from less than a quarter inch or pea sized to over 4 inches or softball sized. The preferred references are actual measurements or approximations based on fixed sizes such as a quarter or a regulation sized softball. “Grapefruit sized” is a far less precise term. One of the reasons for using common objects as references is it allows storm spotters and others to report the size without venturing out into a storm with its associated risks to take actual measurements.

vivian_hailThe largest hail stone reported in the U.S was over 8 inches in diameter with a circumference of over 18 inches.

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Phil Katz-MSU Extension

Crop loss from hail is a significant risk to producers. Depending on where crops are in the growth cycle and the extent of the damage, growers are often cautioned to have a little patience to determine if the crops can bounce back. Many state extension services can provide more information.

 

hail carDamage to vehicles is usually pretty obvious in terms of dents and broken glass. There are some DIY fixes for smaller dents including letting the vehicle sit in the hot sun so the metal expands a bit. The best advice though is to contact your insurance carrier and/or a competent body shop. A worst case scenario is when a new car dealer’s lot or other parking lot is hit. Damage can easily escalate into six figures or more. Several years ago here in the Champaign-Urbana area, dozens and dozens of cars parked at the local airport were badly damaged.

thHail can also damage roofs constructed of various materials. Again, working with your insurance carrier to arrange for an inspection by a qualified roofer is always a good idea. Some damage may be hard for the untrained eye to see and ladder work is often best left to professionals anyway.

Siding on homes also can be easily damaged. Steel or aluminum siding can be dented and still maintain its structural and weatherproof integrity.Bad_Siding_Hail_Damage Hail can absolutely shred vinyl siding and immediate action to cover exposed underlayment or insulation is necessary to avoid more widespread water damage.

 

 

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NOAA Graphic

One question that is often asked is, does the presence of hail, especially large hail, tell us anything about the structure of a thunderstorm? Since hail is formed when water droplets freeze as they are lifted above the 32-degree line by updrafts, it stands to reason that the presence of ever larger hail stones in a storm reflects the strength of that updraft so it can be an indicator of both the strength and height of a thunderstorm cell. Hail is easily seen on radar because of its dense mass. Many videos shot by storm chasers show large hail as part of some tornadic thunderstorms.

Weather Wednesday – Spring Outlook

NOAA’s Climate Center has issued its 2015 Spring Outlook covering flood potential, precipitation, temperature and drought through the April-June period. The flood outlook is for mid-March to Mid-May.

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NOAA Climate Center

According to the outlook, the greatest potential for Spring flooding is in the Northeast along with a portion of the lower Missouri River and other nearby rivers and streams in parts of southern Illinois, southwest Indiana and far northern Kentucky. The near term potential is being driven by snow melt. That melt will also influence the somewhat longer term in that soil moisture will be above average to far above average in those areas.

NOAA Climate Center
NOAA Climate Center

As for temperatures, much of the eastern two-thirds of the nation will experience near-normal temperatures with the West Coast being much above normal. Only portions of Texas and New Mexico are forecast to be below normal.

The outlook calls for above-normal precipitation in the Southeast and the Four-corners area with below normal precipitation in the Pacific Northwest and parts of Minnesota and Wisconsin. The rest of the country will be near normal.

NOAA Climate Center
NOAA Climate Center

Drought conditions will continue or worsen in much of the western third of the country and drought may also spread from Minnesota into Wisconsin.  The drought will improve in eastern New Mexico and Oklahoma.  40% of California is already in an exceptional drought and the predicted hot temperatures and lack of precipitation will exacerbate that situation.

The precipitation and drought outlooks bode ill for the upcoming fire season.

As always, the long term outlook comes with a caveat that specific weather systems can always cause additional flooding and other impacts so readers should always stay alert.

Weather Wednesday – Flood Awareness Week

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This week has been designated Flood Awareness Week by the National Weather Service. Each year flooding is responsible for the deaths of dozens of people in the United States and thousands worldwide.

2014 was a relatively safe year in the United States because of a lack of tropical storms and hurricanes, yet 41 people were killed by flooding. We’ve all heard the phrase “Turn around, Don’t drown!” That is well-taken advice because of the 41 fatalities last year, 27 were in vehicles. Just a few inches of water can sweep a car away. Never drive into a flooded area.Slideshow1 Even if you think you know the street or highway well, it is possible some of the pavement was washed away by the tremendous force of flood waters. Driving into water at night and during other periods of low visibility such as heavy rain is especially dangerous.

We’ll talk about preparation and recovery in later posts, but this awareness week is a good time to talk about protecting lives. The 2014 fatalities were fairly evenly split between areas east and west of the Mississippi River. More males than females died and Texas’ six fatalities were the most of any state. In the first two months of 2015, five people have been killed by flooding.

The National Weather Service has a robust flood safety web site.

There are three major types of flooding…flash floods, river floods and coastal floods. All cause fatalities each year and it would be difficult to consider one more dangerous than another, although, by its very nature, flash flooding can catch its victims unaware. The National Weather Service issues advisories, watches and warnings for each of the types.
During this time of year, river flooding is common and while it is usually well forecast and expected, the force of that flooding needs to be respected. River status maps such as the one below and forecast maps are available through the Weather Service.Clip1These maps are also part of a suite of tools available as part of the Next48 project of the Extension Disaster Education Network which was created by Tom Priddy and colleagues at the University of Kentucky.. You can customize the maps you want to see in your state by visiting the Next48 web site.

There are also special considerations for people living downstream from known hazards such as large dams and other types of impoundments. Be aware of these threats and know how local authorities intend to issue warnings should a dangerous situation occur.

There have been many tragic incidents over the years where campers and cabin dwellers have been washed away by flash flooding. Never camp in unapproved areas. It is tempting to set up camp along a river or stream. If you do, be aware of weather upstream that might cause a rapid rise in water levels. Have an exit strategy. Plan how to get to higher ground in a hurry. If authorities order an urgent evacuation, leave your belongings behind and leave immediately.

Slideshow2Floods are a known and common threat. With a little common sense and advance planning, you can avoid becoming a number in the 2015 statistics.

 

Weather Wednesday – Lightning

This is Severe Weather Preparedness Week in several states. Others may have just observed the week and still others may be doing so soon. Over the next several posts, we’ll cover several topics related to severe weather in greater depth.

NOAA
NOAA

As outdoor baseball and soccer practice, along other activities such as golf, gardening, boating will be on the upswing in coming weeks, we’ll start our coverage with lightning. Of course, the threat of being struck by lightning has been known for centuries. The History Channel recounts a particularly devastating lightning strike that killed 300 people.

The National Weather Service has a very good lightning resource page including actions you should take to protect yourself and others.

As our understanding of how lightning works, the different kinds of lightning and other aspects of the science involved improves, best practices have been refined and much more attention is being given to protecting participants and fans at outdoor sporting events.

NOAA
NOAA

The National Collegiate Athletic Association (NCAA) has developed some guidelines for when to clear the practice field and when to ask fans to leave a stadium. Some institutions have modified these to be even more conservative based on estimates of how long it would take to empty a stadium of fans and where the closest safer shelter is. During the 2014 football season lightning delays and even suspensions were fairly common.

Many states require the installation of lightning alarms at recreational facilities and sports venues. Participants and fans should follow the local guidelines when those alarms are triggered. However, as always, alarms are never a substitute for personal responsibility. There are a variety of smartphone apps that link to databases of recent lightning strikes. They can be a good tool, but be aware that there may be a delay in the process of detecting the strikes, assembling the data and posting in the app. So it is best to assume that the data may be a few minutes old and act accordingly.

As mentioned in the content in the links above, a good rule of thumb is that a 30-second lag between sighting the lightning bolt and hearing the thunder means the bolt was roughly six miles away. And at six miles, you should be headed to a safer place immediately.

Additional resources from eXtension.org are good reads.

Weather Wednesday: When the Great Lakes Freeze

Satellite image of Great Lakes February 2015. NOAA.

 

As of February 25, 2015, the Great Lakes are over 85% ice covered and the coverage is growing weekly.  glsea_curOther than the obvious impact to shipping, what does this really mean?

When the Great Lakes experience heavy ice cover as they have in the winters of 2014 and 2015 there are a multitude of impacts.  Some are beneficial and some are problematic and some are both.

For example, evaporation takes place over open water even in the winter time.  At least partially because evaporation was inhibited in the winter of 2014-15, Lake Michigan water levels last summer increased dramatically over the summer of 2013.  Some of the impacts included reduced usable recreational beach areas. On the positive side, the higher water levels mitigated some of the need to dredge channels and harbor entrances especially along the eastern shore of the lake.  As of February 25, the water level on Lake Michigan was a whopping 21-inches higher than a year earlier and was 8 inches higher than the long term average.  Snow melt and rainfall also are a factor, but the reduced evaporation plays a role. lighthouse

Snowfall amounts are also affected when the lakes freeze.  Lake Effect Snow basically shuts down once the lakes freeze over, a welcomed break for motorists in the Great Lakes snow belt areas.

Heavy ice cover also tends to influence spring and even summer weather in areas close to the lakes.  The temperatures in communities near Lake Michigan were noticeably cooler than inland communities in the spring and summer of 2014, far cooler than the usually welcomed moderating effect of the lake.  One benefit of the late spring is to fruit growers.  The cooler weather delays the blossoming of fruit trees to the extent that the threat of frost damage from isolated cold snaps is mitigated.  And the normal micro-climate of shoreline communities is more pronounced in years when the lakes are ice-covered.

Arcadia, MI. Cool summer of 2014. Author.

Long lasting ice cover also affects the water temperature of the Great Lakes.   Even the normally more moderate lakes remained quite cool for swimming and other warm weather recreation in the summer of 2014.  It is worth noting that there was still visible ice on Lake Superior into June of 2014 and some water temperatures in Lake Michigan were still in the upper-30 degree range on Memorial Day weekend!!  The reduced water temperatures impact how anglers approach their prey.  And the development of algae can also be affected.

It is likely that the ice cover of the lakes will continue to expand for at least a few more weeks this year.

Weather Wednesday: Just what the heck is going on with this winter?

first snow 2013 003The wild winter weather continues this week with snow and ice stretching all the way down into the Deep South.  Brutal wind chills have been common in many areas of the north.  Here in Champaign, we’ve had a fresh snow pack and because of that, little wind and clear skies, our overnight temperature fell to 12-below, 10 degrees below the forecast and 10-degrees below the previous record low for this date in late February.  So what’s going on?

Meteorologist Tom Skilling and his staff at WGN-TV in Chicago have been researching the topic and posted a rather extensive article, the link to which is here.

Skilling’s Facebook posts are always informative and, if you are a weather fan, you may want to like him on Facebook even if you’re not from the Chicago area.

Weather Wednesday: Freezing Rain, Ice Storms and Black Ice

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NOAA graphic

Winter weather certainly has remained in the news this post-Valentine’s Day week. It’s been another major snow event in the Northeast, heavy snow from southern Illinois and Missouri to the south into Kentucky and adjacent states and freezing rain and ice, especially in Georgia, North Carolina and other states in the southeast. Multiple highway fatalities have occurred and over 100,000 people have lost power, mostly due to ice. Bitterly cold temperatures are plunging far into the south on the date this is posted, February 18, 2015.

We’ve written about heavy snow several times and we’ll revisit the topic of how climate change may affect that snowfall, but today we’ll focus on freezing rain, ice storms and “black ice,” all of which are being experienced in parts of the south and southeast this week.

According to the National Weather Service freezing rain and sleet occur when raindrops in a layer of warm air well above the surface fall into a layer of freezing air at and near ground level. Whether the liquid ends up as freezing rain or sleet is determined by the thickness of the layer of freezing air. When that layer is thin, the raindrops don’t have time to freeze so the water freezes on contact with the surface, coating streets, sidewalks, power lines, tree limbs and whatever else is exposed and below freezing. Complicating the situation this week is bitter cold temperatures to follow the snow and ice.

A freezing rain event is escalated to an Ice Storm Warning when ice accumulations of ¼ inch or more are expected. The National Weather Service considers ice storms to be high impact events and if you’ve lived through one or more, you know that to be true. Ice storms can occur across a wide area of the United States and can be very devastating. The single most destructive weather event ever to occur here in Champaign-Urbana, Illinois was the Valentine’s Day ice storm of 1990. The 25th anniversary of the event passed largely unobserved last weekend. Seemingly no one wants to relive that week.

The storm began during a home basketball game at the University of Illinois and ice quickly accumulated. The lights in the Assembly Hall flickered, but stayed on. I was the public address announcer that night and I vividly recall being handed a series of announcements to be read if the main power went off. The final announcement I did read was that game attendees should expect that many traffic signals would be out of commission across town after the game. When I left the Hall I could see the flashes and hear the explosions as electrical transformers failed.

I drove the few blocks to the radio station where I worked at the time. It was operating on generator power. We started to cover the event and things just got worse during the overnight. At one point around 2:00AM I decided to go check on my family and home. I followed a snowplow down a main street as it pushed trees and branches out of the road so emergency vehicles could get through. I turned down my street as limbs were falling behind me and decided to just keep going back to work before the street was completely blocked. Some areas of town were without power for a week. Damage to utility infrastructure, trees, traffic signs and signals and buildings and homes reached into the millions of dollars not counting the loss of productivity and dumpster loads of ruined refrigerated and frozen food.

I relate that account not because it was unusual, but rather because it is typical of major ice events. They can be extremely destructive and expensive.

Finally today I want to mention “black ice.”Black Ice accident Black ice can be every bit as dangerous as a heavy snow or ice storm. It is a very thin layer of ice that is nearly transparent. It frequently forms on bridges and overpasses because that pavement temperature may be colder as the cold air circulates above and below the pavement. Black ice often occurs when snow melts during the day and then the water refreezes at night. Or the temperature drops below freezing after a rainy day. Unlike during an ice storm, black ice is a much greater threat to pedestrians and vehicles than to structures. Multi-vehicle accidents are common when the pavement refreezes and emergency rooms are kept busy treating pedestrians who slip and fall.

Ice storm threats include: