Monday, April 13, 2020

Some Thoughts on the Tornado and Thunderstorm High Wind Event Just Ended

-- This was a major tornado outbreak by any measure -- 
  • 35  26 Deaths Reported So Far
  • Nighttime Tornadoes Caused Severe Damage in Places
  • Some Violent Tornadoes Moved Unusually Fast 
  • Major tornadoes came from what meteorologists call "elevated" thunderstorms which is highly unusual. 
  • At least one of the tornadoes (in Mississippi) was two miles in diameter.
Generally, the forecasts and warnings were good (I'll evaluate my forecast below). Here are some comments I believe will be of interest.

Addition: noon Thursday: It turns out that all of the confirmed tornadoes occurred within the areas of my forecast. While the forecast was too large geographically, the forecast did fulfill its goal. 
My Forecast
Because there are individuals and organizations that need to size up the entire event, I created two forecasts late last week with the goal of providing my readers that type of forecast for what was clearing going to be a major event. 

Thursday's Forecast
Friday's Forecast
Since the event was forecast to start the next day (about 24 hours after the forecast was published), I used all four categories of my risk scale for the first time. 
I called it a "vicious" outbreak and, given the number of tornadoes and fatalities, plus the widespread electrical outages, I believe that characterization was correct.

Map of Tornadoes - What Actually Occurred 
Here is a very preliminary map of the tornadoes over the three days (Saturday night through 1pm CDT Monday). Almost certainly, many more tornadoes will be added as the NWS conducts field surveys. 
Legend:
  • Red Dot = Tornado 
  • Red/Blue Dot = Wind Damage, Possible Tornado (most will be tornadoes)
  • Blue Dot = Wind Damage (a number of these will be converted to tornadoes)
  • Dark Blue Dots = Measured Wind of 58 mph or More 
Considering the lead time (interval from the forecast to the first storm), these look pretty good in areas north of I-40. I had thought the extreme pressure falls in the Mid-Mississippi Valley would pull the warm front farther north than the synoptic models indicated but I was incorrect (the CAMS were another matter). I'm pleased the extraordinary tornadoes in southern Mississippi were (barely) in my "extreme" area.
From a meteorologist
The power failure map is testimony to the extreme winds (tornado and thunderstorm-generated) of this outbreak of extreme storms. The number of customers equates to about 3-million people
So, I believe this qualifies as a "vicious" outbreak and I believe the tornado forecast was quite good south of I-40, but I took it too far north.

Other Thoughts:
While flood warnings have not improved as much as weather scientists expected, the investment in dual-polarizing the NWS's radar network has paid off by being able to see where tornadoes are lofting debris. This has clearly had a positive effect in communicating tornado dangers, especially at night.
The blue-gray = lofted debris in South Carolina during the pre-dawn hours. The north-south yellow = likely debris, also.

Recovery from these storms is going to be hampered by officials' overreaction to coronavirus (given what we now know about CV). If you were, for example, Borg-Warner, would you immediately want to invest and rebuild this plant when some officials are talking about keeping the "lockdown" in place until January? Plus, where are you going to get workers with "social distancing?"

The value of safe rooms (in areas without basements) has been proven again (below) and the danger of mobile homes have both been proven again. It takes a powerful tornado to sweep a slab clean.
And, tragically,
plus, I understand there were mobile home-related deaths in Georgia. There is nothing wrong with living in mobile homes. But, mobile home parks should have underground shelters. That is the law in Kansas and it needs to be in the South.

There were some issues with the warning system that I will cover in a separate article tomorrow. 




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