 On Sunday, May 27th, Ellicott City, Maryland experienced a flash flood caused by a line of thunderstorms that created much devastation in the city. CBS news reported that this flood was so severe that cars floated down Main Street in Ellicott City, Md. There was also a report on Sunday that someone had been missing since being washed away by the flood on Main Street after assisting with water rescues. Unfortunately, on Tuesday the 29th, he was found deceased. This shows how devastating, dangerous, and life-threatening floods can be. The water receded the day after the flood. Overall it is estimated that there were about 15 inches of rain in Catonsville (a town next to Ellicott City). Although the water had receded, The Weather Channel stated that on Tuesday the 29th authorities issued a “precautionary health alert” after a sewer spewed about 500,000 gallons of raw sewage about 2 miles from downtown Ellicott City. The geography of Ellicott City makes it flood-prone. The Washington Post explained that the area is located downhill next to the Patapsco River. Several streams flow downhill towards Ellicott City and Patapsco River, which makes the city susceptible to floods. This is the second time within two years that Ellicott City had a major flood. They had just recovered from a flood in 2016. Hopefully, with much support, the city can make a quick recovery. (credit: The Weather Channel, CBS News, The Washington Post) To learn more about severe weather, please click here! © 2018 Forecaster Brittany Connelly
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 This past Tuesday marked the 7th anniversary of when the city of Joplin, Missouri was impacted by the deadliest and most damaging tornado since records began in 1950. At its peak, this EF-5 tornado was nearly a mile wide, with winds of 200+ miles per hour. From start to finish, the tornado tracked a path stretching 22.1 miles, resulting in 158 deaths and over 1000 reported injuries. On May 22nd, 2011 at 5:34 p.m, a supercell dropped a tornado just east of the Missouri-Kansas border. This tornado tracked due east near 32nd street where storm chasers and eyewitnesses had reported seeing multiple vortices around the main circulation, a typical sign that the tornado is rapidly strengthening and getting larger in size, and right before the tornado became rain-wrapped. Sirens sounded 20 minutes before the tornado struck Joplin as tornado warnings were issued by the NWS office in Springfield, MO. The tornado intensified into an EF-1 as it started to plow through rural areas. From there, the tornado continued to track east as it made its way along 32nd street, where evidence of EF-2 damage was surveyed. At this point in the tornadoes’ lifespan, it was near a ¼ mile wide. This was only just the beginning. Once it crossed 32nd street, the tornado strengthened from an EF-3 to an EF-4 from surveyed damage. At this point the storm was showing a textbook tornadic supercell signature on radar. The radar picture below depicts what a thunderstorm looks like if it is about to or has produced a tornado. If you take a closer look at the radar scan, you can see a purple circle at the end of the hook. In meteorology, this is classified as a debris ball, a sign that the tornado is strong enough to pick up debris off the surface and fling it into the air. The tornado continued to move east toward McClelland Boulevard at 20 to 25 miles per hour where it was approximately ¾ to a mile wide. Once it passed this area, St. John’s hospital was heavily damaged, and the tornado leveled homes which were swept off their foundations. Two schools in Joplin, East Middle School and Joplin High School both suffered major damage from the tornado. The newest part of the high school, the Franklin Technical Center, was destroyed. More EF-4 damage and even low-end EF-5 damage was surveyed along the intersection of South Rangeline Road and 20th street as the tornado continued to destroy well structured establishments. As the tornado passed the city of Joplin, it began to weaken substantially. The tornado finally lifted roughly 5 miles northeast of Granby and east of Diamond, MO around 6:12 p.m. Along the tornado’s path, approximately 6,950 structures were destroyed, and resulting in a staggering number of injuries and lives lost. The costliest tornado in American history, the Joplin Tornado totaled up to $2.8 billion in damage. According the American Red Cross, about 25% of the city was destroyed as of a result of this tornado. Weather Channel’s Mike Bettes appeared on the air to report live from the scene. Struggling to keep his composure, he emotionally reported the destruction that occurred in the city of Joplin. During his broadcast he becomes speechless and starts to tear up. After a moment, he regains himself, chokes back his emotions, and continues his report. The scar this tornado left on the city of Joplin may never be forgotten. Fast forward to 2018, it is amazing to see how this city has grown since this tragedy. Neighborhoods have been rebuilt, and a few memorials have been built around Joplin to remember all of the lives that were lost. To learn more about severe storms, please click here! ©2018 Meteorologist Joseph Marino   A thunderstorm viewed from north Douglas Island, looking east towards Juneau on June 17, 2013. While the Great Plain states are gearing up for prime storm chasing season, Juneau skies remain quiet. While thunderstorms aren’t completely unheard of in southeast Alaska, they aren’t a common occurrence either. A case study on thunderstorm climatology performed by the National Weather Service office in Juneau found that between 1970 and 2011, Juneau observed 16 thunderstorms (or averaging about one thunderstorm every two years).
In order to get thunderstorms, you need three key ingredients: a source of moisture, lift, and instability. Juneau is a maritime climate kept cool during the summer by the Gulf of Alaska waters and largely lacking the instability to create large updrafts that would build cumulonimbus. One important attribute of this reason is latitude. At 58 degrees north, the air is thinner than near the equator. Thunderstorms in the tropics can easily surpass 50,000 feet, but thunderstorms at 15,000-20,000 feet simply cannot be supported. In addition, the town is located next to the Juneau Icefield- the 5th largest glacier field in the world that acts as a “refrigerator” to cap thunderstorm development. When Juneau does get thunderstorms, however, it is mainly the result of strong daytime heating during the summer months. By the summer solstice, Juneau peaks at just under 18 ½ hours of daylight. Combined with moist air from Canada, this could be enough convection to lead to the formation of thunderstorms. Otherwise, thunderstorms may develop inland over British Columbia and the Yukon with cloud bases high enough to clear the Coast Mountain range. Though thunderstorms are rare in Juneau, they are much more common along the outer coast of Southeast Alaska and the Interior, north of the Alaska Range. Late autumn and winter is a typical time of year for thunderstorms in the Gulf, with the warm ocean as the main heat source interacting with the cooler land onshore. Regardless, thunderstorm wind gusts and lightning are still capable of causing hazards with regard to marine vessels, power outages, as well as the potential risk of forest fires. To learn more about severe storms, please click here! ©2018 Meteorologist Sharon Sullivan Impressive GOES-16 View of Training Supercell Thunderstorms (credit: NOAA GOES-16 Satellite)5/1/2018 
DISCUSSION: As the Central United States woke up to the 1st of May here in 2018, many millions of people woke up to the developing threat for widespread severe weather across portions of the Central Plains today. Based on the fact that there was an approaching low-pressure system from the west during the course of the day, this facilitated an effective surge of warm-air to the east of the cold front (i.e., within the warm sector of the strengthening low-pressure system). This surge of warm, moist air in the warm sector of this low-pressure system allowed for robust convective storms to develop during the course of the afternoon hours. In addition, there was also a substantial amount of vertical wind shear which facilitate a more conducive low/mid-level atmospheric environment for rotating updrafts within these developing convective storms.
As the deep convective storms fired up by around 2:00 to 4:00 PM CDT on 1 May 2018, there was also a fairly persistent presence of deeper vertical wind shear across a substantial portion of Nebraska. This more persistent deep vertical wind shear allowed for more persistent supercell thunderstorm activity to persist through the mid- to late-evening hours as is reflected by the tweet attached above (courtesy of WeatherNation Meteorologist Dakota Smith). It is also worth noting that such persistent late-night supercell thunderstorm activity is a MAJOR threat to both life and property since nocturnal convective storms can often bring prolific natural hazards which can "sneak up" on unsuspecting people in the path of such storms. Therefore, if you are ever in the path of nocturnal convective storms, always be sure to remain aware of the current severe weather situation in your "neck of the woods." This way, whenever you are under a severe weather threat, always stay closely tuned to the local forecast as it evolves and always keep a severe weather plan in place. To learn more about other high-impact severe weather events from around the world, be sure to click here! © 2018 Meteorologist Jordan Rabinowitz |
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