July 21, 1998 Severe Thunderstorms

Showers and thunderstorms developed along a warm front in the morning and early afternoon over Pennsylvania. The airmass was very moist, allowing for thunderstorms to erupt very easily. The limited morning sunshine that was present was more than enough to trigger severe thunderstorms along the front. Thunderstorms, some severe, also developed behind the front in the late afternoon. Dew points were in mid 60's to mid 70's, showing how high the moisture content in the atmosphere was! High temperatures were well into the 80's and low 90's across the state, with heat indexes in the 90's to over 100 in some areas.

The most significant damage in PA on this day occurred from Conyngham, southeast to West Hazleton in southwestern Luzerne county. An intensifying thunderstorm moving out of Columbia county in the early afternoon became severe near Conyngham. It was showing signs of rotation, but it was not a concentrated area... and rather a more broad area of rotation. Also, remember that only about 40% of all rotating thunderstorms produce tornadoes. The other 60% produce large hail and destructive downbursts. That was the case today, when a microburst cut a swath several miles long in far southern Luzerne county. A severe thunderstorm warning was issued by the NWS in Binghamton for the western half of Luzerne county, including the Conyngham area, more than 30 minutes before the storm struck. This gave people ample time to seek shelter. Golfers at a local Golf Course did just that. If they hadn't, it is more than likely that there would have been injuries and/or fatalities.

The interesting thing about this thunderstorm is that it produced the damage when it was in its dissipating stage... although this is not all that uncommon. When looking at the reflectivity radar data, DBZ values were above 60 previous to the damage, and below 60 when the damage was occurring. This and other aspects all means that the thunderstorm was in its "collapsing stage" during the damage, as mentioned above. Also, the damage did not occur in the core of the thunderstorm, but rather on the southern edge. A radar image from around the time of the onset of the damage can be seen here. As mentioned, the storm looked much better on radar just 5-10 minutes earlier... which can be seen here . If you are not familiar with the county layout in this area, the Conyngham/West Hazleton area is around the center of the radar picture... by the southern part of the thunderstorm cell.
Additional radar images can be found here.

The first damage started in Conyngham around 2 pm EDT. Peak winds in this area were probably around 70 mph... several feet above ground level. Dozens of trees were snapped and uprooted... including several very large ones which were snapped like toothpicks. Power poles and lines were also downed. One pine tree was snapped and thrown though the air like a guided missile... penetrating through the roof of a nearby house. From inside the house, you could see that the tree had penetrated almost a foot into the house... through the roof and ceiling. Cars were buried, and numerous houses were damaged by the falling and flying trees and limbs. One had its entire corner crushed, another had its deck crushed, while others had roofs crushed. Roads were blocked for a time as crews cleaned up the debris left behind. On the golf course is where the most trees were probably downed. Lawn furniture was thrown hundreds of feet! Several medium sized wooden pavilions, belonging to the golf course, were destroyed.

As the severe thunderstorm moved just southeast of Conyngham, damage continued in Hazle township. Two homes just off and west of Interstate 81 had their roofs torn completely off. In addition, a garage was leveled by the strong thunderstorm winds. As the dangerous severe thunderstorm continued its trek southeast, it moved into West Hazleton. At the Laurel Mall, many vehicles were damaged, as the thunderstorm winds downed large light poles in the parking lot.

In all, dozens of homes were damaged. Most residents thought a tornado had hit. After a NWS survey however, it was confirmed to be a microburst -- a powerful burst of damaging thunderstorm winds that accompanies many severe thunderstorms. There was no evidence of tornadic damage, and a few residents described the wind as a "wall" moving through and pushing everything over. This is an excellent description of thunderstorm winds. Winds at the most intense time were around 90 mph, but were generally between 60 and 70 mph. Damage totals approached half a million dollars.

Another severe thunderstorm produced isolated damage in Lackawanna county. Some trees were blown over, especially in the Clarks Summit area.

The second most significant downburst event of the day in PA occurred when severe thunderstorm winds in extreme eastern Lebanon county hit the Myerstown area. The damage occurred in Jackson township, and caused a 2 mile long, 1 1/2 mile wide, swath of damage... crossing route 422 just west of Myerstown. Along route 422, as many as ten utility poles were snapped in half in a row. One landed on and damaged a car. A barn had parts of its roof torn away, and another barn was destroyed. Three mobile homes were damaged at the Country Acres Mobile Home Park. One now has a nice view of the sky, as a large tree crushed the roof and walls. Maximum winds were estimated around 80 mph, but were generally around 60 mph. Non-severe hail... approximately marble size (1/2")... also fell with this thunderstorm.

In northern Somerset county, a dangerous severe thunderstorm moved along and north of the PA Turnpike. Trees, numerous in some areas, were downed by thunderstorm winds in Somerset, Jennerstown, Sipesville, and Shanksville... where a tree fell on and damaged a house. There were only a few other reports of isolated damage around the area. Trees were downed by thunderstorm winds in Everett (Bedford county), Amaranth (Fulton county), and Quarryville (Lancaster county), while power lines were ripped down near Sabinsville (Tioga county).

Severe thunderstorms were also producing extensive damage in Wisconsin and Michigan today. Winds from the thunderstorms were between 60 and 100 mph in numerous areas. Luckily, the threat for damaging downbursts was known before hand... with winds blowing 40-50 mph less than a mile above the surface! Since all thunderstorms easily grow much higher than a mile into the atmosphere, it was clear that the winds would be mixed down to the surface... and become even stronger. The atmosphere was also extremely unstable... resulting in very rare CAPE values -- up to 7,000!! In southeast Michigan, 2 people were killed and 2 injured when thunderstorm winds blew down the canopy of a Blockbuster Video store. All four people involved in this tragedy were in one family. One person killed was a young boy - he was killed instantly, as his head was crushed. His father was seriously injured, and rushed to the hospital. With critical injuries to his internal organs, it was only a matter of time before he would succumb to his injuries. Two and a half weeks after being in the hospital, the father of the family died. The two other children that were injured survived the severe thunderstorm after being treated at the scene, but were now, sadly, without a brother and father. Two other people in southeast MI were injured from thunderstorm winds, one knocked unconscious from a falling tree landing on the car he was in. His injuries were bad enough for a stay in the hospital. Besides the unfortunate loss of life, well over a thousand buildings were damaged or destroyed (about 1,000 homes were damaged just outside of Detroit alone!). Businesses/stores and homes had roofs torn off, with extensive water damage in some businesses. One was declared a total loss. Porches were ripped off some houses, and plate glass windows were blown in at stores and homes. Hangers at an airport were moved off their foundations, and planes were damaged. Gas pumps were blown over, traffic signals and store signs blown down, and newspaper stands were overturned. In Detroit, boxcars were rolled into a building by thunderstorm winds, causing significant structural damage. Dozens of vehicles were damaged or destroyed (approximately 35 were destroyed, with many more damaged). Thousands of trees were downed along the path of the severe thunderstorms! Some of the few trees that survived the strong tornado in northeast Wayne county on July 2, 1997, came crashing down by the powerful thunderstorm winds. Power companies reported that this bout of severe thunderstorms was among the worst weather systems in their history (it ranked number 4)... concerning power outages. People had to wait over a week to get electricity again in some areas! Miles upon miles of power lines and poles were wiped out.

In southeast Wisconsin, thunderstorm winds injured at least 13 people, and caused more than 2 million dollars in damage. Quite a few office buildings... including some in downtown Elkhorn... were damaged. Some had considerable damage, with one destroyed. Since these were industrial office buildings, thunderstorm winds were estimated over 100 mph. More than a dozen cars were damaged. As the downburst continued moving east of Elkhorn... the damage swath became wider --- 6-8 miles! Hundreds of trees were downed, along with power poles and lines. Several farm buildings were destroyed. A plane which was tied down at an airport was still overturned! Perhaps some of the most impressive damage occurred along and near Interstate 94 in Kenosha county... west of Somers. In this area, it was described as looking like a bomb exploded. Seven tractor trailers were blown over on the Interstate, and large highway signs were blown to bits. Hundreds of trees were downed, corn fields were damaged, a barn was leveled, and several homes were damaged.

As the severe thunderstorms moved across northern Ohio, damage was not as widespread, but there was still pockets of intense thunderstorm wind damage. Across the northern third of OH, where all the damage occurred, over a thousand trees were downed, along with many power lines and poles. Dozens of homes and mobile homes were damaged by falling trees. Thunderstorm winds completely destroyed three barns and a house in Putnam county. Another house had its second floor completely ripped off by the strong thunderstorm winds! An elementary school sustained extensive roof damage, with major water damage to the inside of the entire school. A tree limb was also downed onto a car by the thunderstorm winds, seriously injuring a man inside. He is now paralyzed. In Milan (Erie county, OH), thunderstorm winds around 70 mph badly damaged the roofs of the town hall and police station. Hundreds of trees were also downed in that area. In Huron county, a barn was picked up and thrown, while three hay wagons were tossed around by 60 mph thunderstorm winds. A man was seriously injured in Norwalk when thunderstorm winds downed a tree onto his vehicle. He was in critical condition at the hospital. In Cuyahoga county, ten homes were damaged in Westlake. In Bay Village, a car and house were damaged by falling trees. Thunderstorm winds were measured at 58 mph in Cleveland, with estimates in surrounding areas up to 60 mph. In Northfield Village, Summit county, thunderstorm winds injured another person as a tree fell onto a car. In several other counties in northern Ohio, trees, tree limbs, and power lines were blown down, and numerous houses sustained damage, many to roofs.

Go here for a complete listing of all images/text available for this event.