Severe weather risk is currently low, but strong storms possible over 4th of July weekend
The risk for severe storms remains far west of Pennsylvania over the next couple of days. Severe weather is common during the summer months, but not as common as one might think. It all comes down the dynamics or ingredients in the atmosphere. Those ingredients include heat, instability, and lift.
Another hot and humid stretch of weather is on tap for the long Holiday weekend. Along with highs in the low 90's, expect some showers and thunderstorms for Saturday and Sunday. As of now the risk for severe weather appears low, but there could still be a few strong storms. The heat and humidity will kick-off some thunderstorms, but the severe indices (ways to measure the severe risk) remain low. It comes down to the forcing mechanism or in this case the cold front. More or less a lack of contrasting air masses keeps the severe risk low for Pa.
During the summer months we tend to see more torrential downpours with a good deal of moisture in place and a slow moving cold front. Tornadoes, gusty winds, and hail tend to be more common during the spring and fall months with fast moving fronts producing greater lift in the atmosphere. Another player is contrasting air masses. The greater the difference between cold and warm air the greater threat for severe weather. This happens more so during the transitional seasons better known as spring and fall. Late spring brings the greatest threat of severe weather.
Let’s look back to the evening of May 31, 1985, when a devastating and deadly tornado outbreak struck the Northeastern United States and Canada. The majority of the tornadoes that touched down in PA were further north and west. According to the National Weather Service, 43 tornadoes and numerous damaging thunderstorms tore across Ohio, Pennsylvania, New York, and Ontario. This event was the deadliest tornado outbreak of the 1980's; killing 89 people in total, injuring more than 1,000 others, and racking up more than $600 million in property damage.