30 June 2012
Many people now know a term that only meteorologists and weather geeks usually know.
Derecho. (It’s pronounced “da ray show”)
A derecho is a fast-moving cluster of thunderstorms that produces very high winds, and moves very rapidly. They like to form in June and July, and they favor certain areas of the country like the Midwest, Great Lakes, and Mid-Atlantic/Pennsylvania. They also tend to form on the north side of intense heat waves. This one fit the bill all around.
As I walked into the WBOC-TV Newsplex here in Salisbury, Maryland at 1:30 PM Friday, the heat index was 111. It was beyond brutal, but as I started looking at the charts and working up the forecast, I noticed a cluster of storms near Gary, Indiana had developed. An hour later it was stronger and was moving rapidly through North Indiana. This caused my suspicions that we might have a derecho event in the making to grow. Another hour later, and the damage reports were streaming in from Ohio, and there was no doubt.
The only question now was if it would hold together and affect Delmarva some 700 miles away. I notified our newsroom that we could see some strong storms late tonight and mentioned it on air during the early evening newscasts. By ten PM, the watches and warnings were coming fast and furious, and during the 11 PM newscast it hit he DC area with 70 mph winds causing massive power outages. The wind arrived in Salisbury around midnight, and let me tell you it really howled. We got our power back at 3 AM and we feel lucky.
The DC area (at last report) had two million without power! With the heat wave expected to push the heat index to 110 there Saturday, this could be a real disaster in the making. The elderly especially cannot handle heat well, and we can only hope they have the power restored before the high heat returns in a few hours. It’s not only DC though, the power was knocked out for millions from Indiana to Delaware Friday night, and many of those areas will see intense heat again Saturday.
There have been some notable derecho events but this one will definitely be one for the books. It happened on one of the hottest June days ever recorded in many states. Nashville set a new all time record high at 109 degrees, and so did several other cities! It has been a week to remember for forecasters with the heat, the wildfires and now a 700 mile long derecho that traveled at 75 mph across at least 8 states from Indiana to Delaware.
Derechos are well-known to forecasters and the NWS offices issued strongly worded severe thunderstorm warnings well ahead of the line. A severe thunderstorm watch was issued as well and the only ones who were surprised by this were those who either ignored the warnings or were totally out of touch with any media/internet. For those who were affected by this storm and want to know more about derechos, this website is very detailed.