august 7th 2023 severe weather outbreak

An outbreak of severe weather occurred across our area on Monday, August 7th. Widespread significant wind damage and a few tornadoes occurred, as well as very large and damaging hail. This is an in-depth recap of the events that occurred that day, as well as the overall severe weather set up.

​Let’s first talk about how the atmosphere was set up. We were warm, humid, and unstable with highs in the 80s and dew points in the low-mid 70s. This led to CAPE in the 2,000-3,000 j/kg range which is more than sufficient for severe weather. We also had very strong forcing thanks to a potent low-pressure system and cold front. Combined with strong wind shear, this set the stage for a significant severe weather event that was forecasted 5 days in advance, giving plenty of time to prepare.

The first tornado occurred in far NE Carroll county and tracked NE into extreme SW York County. This tornado was rated EF1 with winds of 105mph. Severe damage to trees and powerlines occurred northwest of Manchester, and a tight velocity couplet combined with a drop in the CC product indicate a tornado was ongoing. However, NWS Sterling never did a survey for this area. However, when it crossed into York County, it became the responsibility of NWS State College. They did do a survey of the area SW of Glen Rock and determined that this was indeed a tornado. Because of this, we can infer that the tornado first touched down in NE Carroll, and at least intermittently resulted in damage as it crossed into York County.

A second tornado touched down further to the NE in East Hopewell Township, again in York County. This tornado was also rated EF1 and did significant damage to trees and powerlines, as well as flattening numerous fields of corn. This tornado was also very visible on radar with a very tight couplet on the velocity product. This tornado touched down at 5:24pm and lasted for just over a mile and a half, and the width was approximately 50 yards wide. The tornado had maximum winds estimated at 107mph.

Further south prior to the tornadoes, extensive straight line wind damage occurred between 4:30 and 5:30pm across Carroll and Baltimore counties but especially Carroll County. Hundreds of trees and dozens of power lines were blown down. A wind gust to 80mph was recorded in Middleburg, and wind gusts around 80-90mph blew down dozens of power lines onto cars in Westminster. Many areas in the pink circle on the Carroll County graphic had winds between 70 and 90mph. Winds were weaker further south, but still gusted between 50 and 60mph across central Maryland resulting in sporadic damage. A video of this storm can be found at this link from our very own Forecaster Joey.

The northern end of the bow echo also produced significant straight line wind damage in Adams and especially York County PA. Widespread 80-90mph wind gusts occurred with severe tree and power line damage according to NWS reports. Wind gusts reached 104mph in Shrewsbury Township where power lines were snapped near the base and hardwood trees were snapped. Like when it came through northern MD, it took on a classic “S” shape indicative of very damaging wind gusts. This northern end of the bow echo is what produced the tornadoes.

​Hopefully this puts into perspective that we don’t need tornadoes to have life threatening weather and severe wind damage. 80mph straight line winds do just as much damage as a tornado will and you need to take it seriously and move to a shelter.

Forecaster Jack and the CMD team