Monday, May 2, 2016

Science Behind the Recent Hail Storms

Understanding the science behind the recent severe thunderstorms in Edgar County is easier when you know the science behind a general thunderstorm.
Thunderstorms require three ingredients to form – moisture, lifting, and instability. Highs on April 26 topped out near 80 degrees as southerly winds brought in warm moist air from the Gulf of Mexico. These conditions fulfilled the first ingredient; the second and third arrived along an advancing cold front. A cold front is the leading edge of an air mass that is cooler than the air already at the surface. Since cold air is denser than warm air, the front lifts the warm air up into the atmosphere and it is replaced by the cooler air. This interaction between the air masses destabilizes the atmosphere and with that instability, forms a thunderstorm. Similar conditions were in place Sunday as the sunshine heated the atmosphere and it became unstable.
Once the ingredients are in place, the lifting produces cumulous clouds as the rising air condenses and establishes an updraft. The updraft supports the thunderstorm by ushering warm, moist air into the storm. Eventually, the moisture condenses into rain drops and they fall when they are too heavy for the updraft to keep them in the cloud. 
The storm that would drop hail on Paris developed around 3 p.m. April 26 across northern Clark County. With ample instability and moisture, the cell thrived, and continued to develop over Paris. The winds in the storm’s updraft began to lift raindrops high into the atmosphere where they froze and collided with other droplets. As these droplets started falling back to the surface, the updraft caught them and once again lifted them into the sub-freezing portions of the atmosphere where they grew into hailstones. This cycle continues, forming larger and larger hail, until the updraft can’t support the hailstones and they fall to the surface.
Around the same time, the storm stalled along the cold front, barely moving to the east. The nearly stationary storm drenched the city in heavy rains and dropped up to golf ball size hail across eastern portions of the city and points east along the Clinton Rd. and U.S. Highway 150.
As one section of the storm weakened, another rapidly developed and took its place, resulting in periods where the hail would briefly stop before another round began. This phenomenon is known as “training” where storms will continually form over the same area and barely moveSunday’s storm; however, was a little different.
Developing over Moultrie County in central Illinois, this cell grew in strength and intensity by feeding on moisture and daytime heating as it pushed east-northeast over Coles County. Once it crossed Interstate 57, its updrafts rapidly intensified, blowing rain and hailstones high into the atmosphere. The updraft was strong enough to support two inch size hail as it passed over Oakland, but continued to intensify and produce three inch size hail south of Brocton.
As the storm moved into western Edgar County, it began to rotate. Rotation in a thunderstorm is caused by wind shear and a strong updraft. Wind shear is found in the upper atmosphere where horizontal winds shift suddenly in direction and speed. If a thunderstorm grows tall enough, its updraft – the winds supporting the thunderstorm – can force the horizontal winds to spin vertically, causing the storm to rotate. If these spinning winds in the cloud connect with winds at the surface, a tornado will form. This storm didn’t produce a tornado, but a funnel cloud was spotted near Redmon. 
Sunday’s storm was considered a “supercell” because of its strong, rotating updraft that generated very large hail and funnel clouds.

Tuesday, April 26, 2016

Severe Weather Outbreak Forecasted for Tuesday

The Storm Prediction Center has highlighted a Moderate Risk for severe weather for areas from Nebraska to southern Oklahoma on Tuesday. In that area, a tornado outbreak is possible with a few strong tornadoes and large hail. Eastern Kansas is bearing the brunt of the system, and cities like Witchita are preparing now for potential storms/tornadoes as well as cities like Tulsa and Oklahoma City further to the south. But before those storms developed, a line of storms pushed its way across Missouri. This line became severe just northwest of Kansas City, MO, capable of producing 60 mph winds and large hail. It was severe warned across its entire path through KC and Jefferson City, and is now knocking on St. Louis's western edges. A Severe Thunderstorm Watch has been issued for portions of western and south central Illinois including Springfield, Taylorville, and Effingham as the storms push toward those areas. Numerous cells have also developed across east central Illinois, but those are expected to become severe. If they do reach severe limits, they shouldn't have enough energy to maintain that strength for long. While storms are popping in Illinois, the most severe storms look to impact portions of the Great Plains this evening and then move into areas overnight that have already dealt with severe storms. Spring storms have finally arrived!

Monday, April 18, 2016

20th Anniversary of Illinois' Largest Tornado Outbreak

The 20th anniversary of Illinois' largest tornado outbreak on record will be marked Tuesday, April 19 (the outbreak occurred in 1996). After surveys were conducted, a total of 39 tornadoes touched down across the state causing 74 injuries, one fatality, and a damage estimate in excess of $100 million. Ten of those tornadoes spawned from one supercell thunderstorm that produced an F2 tornado in Jacksonville and F3 strength tornadoes in Decatur, Champaign/Urbana, and Ogden. Before that supercell entered central Illinois, another supercell thunderstorm dropped two tornadoes in Coles County and two more in Edgar County. Both of Edgar County's tornadoes touched down just northwest of Paris. One touched down at 5:10 p.m., three miles northwest of Paris, destroying a barn. It continued east-northeast and damaged six farms in the area, including the destruction of several machine sheds, a couple barns, and grain bins. One residence had moderate roof damage and another had broken windows caused by baseball-sized hail. The tornado lifted at 5:16 p.m. after crossing Highway 1 three miles north of Paris. It was later rated as an F1 tornado with a max width of 440 yards. The other tornado touched down at 5:12 p.m. 1.5 miles north-northwest of Paris, near Cherry Point Rd. and County Rd. 200W, destroying a machine shed. It lifted briefly and touched down again at the intersection of Steidle Rd. and Tucker Beach Rd., damaging a 3-car garage. It continued east-northeast and damaged another machine shed, numerous trees, and a baseball field. At Twin Lakes Park, several benches, trees and a small shed were damaged. It traveled across the lake and flipped a boat lift, before dissipating at 5:16 p.m. This tornado was rated an F0 tornado with a max width of 220 yards. Had this tornado occurred present day, it would have traveled across the parking lot on the Paris High School campus just south of the railroad crossing. Several windows were blown out of homes in Brocton as well as Paris where golf ball-sized hail fell. Information about the tornadoes is courtesy of the National Weather Service office in Lincoln.

Monday, April 11, 2016

Spring Looks to Finally Arrive

After a week of cold, windy, rainy, and even snowy conditions, spring finally looks to make an appearance. Numerous Freeze Warnings have been issued for Edgar County over the past 2 weeks (4 to be exact). Overnight lows have dropped into the upper 20s which has threatened new plant growth. Another warning is in effect for Tuesday night, but hopefully it will be the last since the average last day for a spring freeze (28 degrees) is April 5. Friday evening, there was enough cold air above the surface to allow sleet, snow, and graupel to form.Cloud cover and northwesterly winds have not help the situation any since they have held down temperatures during the day. However, after a rainy and cloudy Monday, the weather looks to improve and go from below average temperatures to above average temperatures. Tuesday looks to be sunny and cool with highs in the 50s, but from there, temperatures are on a steady increase with abundant sunshine. By the weekend, temperatures will be near or above 70 degrees! Long-term forecasts show the jet stream staying to the north which will keep a flow of warm air streaming into the Midwest from the Gulf of Mexico.

Monday, April 4, 2016

Wicked Winds Rip Through Central Illinois

A low pressure system moved across southern Wisconsin Saturday afternoon, creating a tight pressure gradient between it and the high pressure in the Great Plains. If the pressure gradient tightens, the winds will will become stronger as air rushes toward the low pressure system from the high. The National Weather Service issued a Wind Advisory for Edgar County Friday night for wind gusts near 50 mph, but there were times Saturday where sustained winds and wind gusts reached High Wind Warning criteria. The Indianapolis office did upgraded their counties, including Vermillion and Vigo, to the warning late Saturday afternoon. Some of the top wind gusts in central Illinois were 66 mph south of Newman, 62 mph in Springfield, 61 mph in Mattoon, and 59 mph Arcola. These winds, if produced in a thunderstorm, would be warned under a Severe Thunderstorm Warning. Paris's top wind gust was 56 mph at the Edgar County Airport. EnerStar battled power outages in their rural areas most of the afternoon as the winds knocked down trees. Numerous semis, trucks, and trailers were blown off roadways, including one north of Paris on Route 1. 10 miles southeast of Paris, numerous trees were snapped or uprooted, siding was partially blown off a house, and part of a roof was blown off an outbuilding. A dust storm was reported in Shelby County, IL between Shelbyville and Windsor. In Terre Haute, a metal communications tower fell on the old jail and a nearby law office just across the Wabash River. After calming down Saturday night (when temperatures dropped into the upper 20s), the winds picked back up from the south Sunday, but they weren't as bad as Saturday's winds.

Monday, March 21, 2016

Severe Weather Strikes Central Illinois Tuesday

Last Tuesday (March 15), severe storms rapidly developed across northeastern Missouri and tracked into western Illinois prompting Tornado Watches and Warnings as well as Severe Thunderstorm Watches and Warnings. Crossing the Mississippi River near Keokuk, Iowa, Tornado Warnings were issued as reports of ping pong ball sized hail started to come in. Tornadoes would eventually be confirmed just to the north and northeast of Macomb, Illinois, the home of Western Illinois University. Other cell developed around 6:30 p.m., north of St. Louis and began tracking straight toward Illinois' capital: Springfield. Numerous local and national reporters were there as election results were starting to stream in; however, just before 7:45, the National Weather Service issued a Tornado Warning for northern Sangamon County that included Springfield. Sirens wailed as reporters scrambled for cover. A funnel cloud was reported over downtown Springfield as lightning illuminated the sky. A tornado was confirmed Wednesday on the western edge of the city. Another tornado was confirmed within the city limits of Peoria, Illinois. A Weather Channel meteorologist was live along the river as sirens sounded across the area. These supercell thunderstorms continued to race northeast toward Chicago and joined together producing damaging winds and large hail. Locally, large hail fell in northern Clark and southern Edgar counties Tuesday night, prompting a Severe Thunderstorm Warning. TV station employees across Central Illinois had a busy night as storm warnings and election results battled for the bottom of the screens.

Monday, March 14, 2016

Spring Storms Make an Appearance

An Enhanced Risk for severe weather was outlined by the Storm Prediction Center Sunday, March 13, 2016. All types of severe weather would possible across Arkansas, eastern Oklahoma, western Tennessee, and northern parts of Louisiana and Mississippi including damaging winds, large hail, and tornadoes. Three Tornado Watches were issued through out the day stretching from eastern Oklahoma to points to the east of Memphis, Tennessee. Confirmed tornadoes and radar-indicated rotation prompted Tornado Warnings across a large part of Arkansas and even one for downtown Memphis! Ping Pong ball size hail was also falling from the skies at one point. There were confirmed tornadoes and the National Weather Service will conduct surveys today to determine ratings. Tuesday, the day voters in Illinois will be headed for the poles, the Storm Prediction Center has placed roughly the northern 2/3 of the state under a Slight Risk for severe weather. Damaging winds look to be the primary threat, but large hail and tornadoes will also be possible. Newsrooms will be busy enough with election results, but add in a couple of severe storms and all of the local television stations in Illinois will be scrambling to keep viewers updated with the latest information. Will Donald Trump and Hillary Clinton's election results dominate the bottom of the screen or will radars and crawls, warning of severe weather, hit the air waves? Now that March is almost halfway through, it looks like Mother Nature is starting to through tornadoes and severe weather into the picture across the country.