Storm recap… more of the same this weekJuly 2nd, 2012 at 8:51 am by Jamie Jarosik under Weather
What a stormy (and HOT!) weekend it was here in the Miami Valley. We started with the severe thunderstorms Friday that produced widespread wind damage in our area. This occured as a “derecho” moved through during the late afternoon and evening hours. What exactly IS a derecho? Here is the official definition from the NWS:
“Derecho: (Pronounced day-RAY-cho), a widespread and usually fast-moving windstorm associated with convection. Derechos include any family of downburst clusters produced by an extratropical MCS, and can produce damaging straight-line winds over areas hundreds of miles long and more than 100 miles across.”
The peak winds that affected the Miami Valley on Friday were in the range of 70-80 mph–very similar to those of the hurricane Ike windstorm back in 2008. The strong winds did not last nearly as long as the Ike windstorm, but they lasted long enough to bring trees and powerlines toppling to the ground… to do significant structural damage in spots… and to bring about injuries to people in our area. Hundreds of thousands went without power in the Miami Valley… and tens of thousands remain without power. With Ike, the weather behind the storm wasn’t too hot or cold. So while we didn’t have power… we were still relatively comfortable. THIS time around, the heat and humidity are not giving us a break… it can be a dangerous situation. For more detail on the Derecho, check out the NWS official storm summary:
Notice in the report above, there were no tornadoes in the area… this was a STRAIGHT LINE WIND event. These winds can easily be just as strong as a tornado’s winds… they just don’t twist like a tornado… they blow violently in one direction. The NWS did receive many reports of tornadoes on Friday, and Meteorologist Tara Hastings wrote a great article about what these people most likely saw:
Here is some more interesting info on the science/physics behind this historic “Derecho”–written for the DC area, but gives a good idea of what was going on in the atmosphere across the region:
We had a quiet day on Saturday, but thunderstorms returned on Sunday. The storms did not quite have the coverage of the previous event, but the winds were almost if not just as strong in spots… and even if you didn’t see rain, you probably saw some sort of forceful wind as a gust front came through. Once again, these storms created widespread damage across the region:
Whenever it is this hot and humid, thunderstorms will typically have the potential to become strong to severe during peak-heating. Rain-cooled air aloft can sink quickly to the surface, and then spread out in all directions, producing these destructive winds. Thunderstorms with great heights and strong updrafts will also have the potential to produce hail… and you can see we did have several hail reports yesterday.
The stationary front that has been in the area throughout the weekend is still draped across the region today. We could see a spotty shower or thunderstorm develop later this afternoon, and a better chance will actually come overnight and into Tuesday morning, as it begins to lift north as a warm front:
The SPC does not include our area in an elevated risk of severe weather at this point, but I wouldn’t rule out the potential for any of these storms to approach severe limits. We will keep an eye on things. The hot and unsettled weather pattern will stick through the end of the week. Be sure to check on those who you know do not have power… make sure they are finding ways to stay cool, and safe. An EXCESSIVE HEAT WARNING is in effect for Montgomery County today, and most of our outlying counties are still under a HEAT ADVISORY. These likely won’t be the last heat headlines we see through the week, as temps could even heat up near 100 again by the time we get to next weekend.