Marine Thunderstorm Wind · Atlantic North

Strong gusty winds associated with the derecho produced measured wind gusts of 49 knots (57 mph) in Cape May and 44 knots (51 mph) in Ocean City. Comparable wind gusts were estimated by Skywarn Spotters in Sea Isle City and Wildwood.

A well-organized cluster of thunderstorms with a history of producing widespread damaging winds advanced into a hot, unstable airmass over the Mid Atlantic. This derecho produced widespread, significant wind damage from southern New Jersey southward into the Delmarva during the late evening and overnight of the 29th.

Strong thunderstorm development began across the Midwest and Lower Great Lakes regions during the afternoon of the 29th, with storms initiating across northern Illinois, near Chicago. Strong mid-level winds and an unstable airmass contributed to rapid development as well-organized storms progressed from northern Illinois through Indiana and Ohio. This robust convection continued to track southeastward into an airmass that was even more unstable due to abundant daytime surface heating. Late afternoon temperatures had peaked mainly in the mid to upper 90s with high humidity throughout the Mid Atlantic states, and as the potent thunderstorm cluster progressed from the Great Lakes to the central Appalachians and into the Mid Atlantic by late evening, thunderstorm activity was reinvigorated.

A robust gust front outpaced the main thunderstorm line, producing strong wind gusts as it traveled from the eastern shore of Maryland into Delaware and southern New Jersey. Shortly thereafter, the potent thunderstorm line tracked through the region, with additional damaging wind gusts. One cell in particular around Baltimore, MD experienced rapid intensification and expansion as it raced eastward into northern Delaware and southern New Jersey. Destructive wind gusts, between 65 mph to nearly 90 mph, were measured as this derecho tracked from the Lower Great Lakes to the Mid Atlantic coast.