SQUALCON Watch Today and Tuesday

UPDATE 4:35 pm
Well, other than some heavy rain, not much else to report on from here in SW Jefferson County. Been surrounded by several warnings but nothing significant from this first round.
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UPDATE 3:30 pm
Went to a different spotting location this time, still did not find anything worth reporting. However, new cell poised to move into the area. Don't yet know if rain-cooled air will choke the wind threat. Will just report from my house this time.
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UPDATE 1:05 pm
High-end Severe Thunderstorm Watch issued for much of our region. Widespread wind damage and power outages possible. Moderate (60%) chance for at least one wind report of near hurricane force. Upgrading SQUALCON Index to 4.6.

UPDATE 12:30 pm
60-65 mph winds common along this line.
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UPDATE 12:20 pm
Wind damage reports coming in from Indianapolis...NEW watch to be issued for Louisville and surrounding locations in a few minutes.
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UPDATE 11:45 a.m.
Storms reaching Indianapolis...Looking at camera shots
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UPDATE 11:10am
SPC shifts severe threat farther west. Current radar shows possible beginning of a bowing line northwest of Indianapolis. If this line holds together, could the center of the bowing line track just west of Louisville between 2 and 3 p.m.?
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The threat for severe weather with widespread, yes, region wide, damage is expected today and into tonight for some of us. Tuesday's severe threat may include a higher tornado risk, especially across eastern Kentucky.

I am assigning a SQUALCON of 4.4 for our region of Kentucky today with several areas reaching wind speeds that will exceed 55 mph. In fact a possible derecho may occur if it meets specific criteria.

Think of a derecho as a wind avalanche. A typical avalanche feeds on a rapidly accelerating collection of snowfall that covers a great distance down a mountain side producing enormous momentum. Similarly, a derecho feeds on a collection of recycled atmospheric processes accelerating wind speeds over a great distance and creating enormous momentum thus widespread damage along its path.

Looking at the progression of a derecho on radar is helpful. The typical bowing out line segment (outflow) with a rain shield wrapping around and into the center of the bowing line (inflow on back side) shows where the strongest or most damaging part of the storm exists.

The last derecho that affected the region was exactly 11 years ago. That one had winds exceeding hurricane force along the leading line and produced tremendous damage.

Therefore, I may increase the SQUALCON value to a rare 5.0 if it appears that the 'avalanche' of wind will likely occur.

Timing these storms can be problematic. Once the cluster forms far to the northwest today, the line will gain momentum or forward speed. So, we'll have to wait and see if a cluster forms first and try to time the main line's arrival.

Otherwise, it is possible that storms may fire up ahead of the main line thus dirtying the line's forward momentum some. But it still looks likely that damage will occur anywhere along that line.

Flooding appears to be a threat as well. Many Kentucky and Southern Indiana residents have seen too much rainfall this month and last month as well. This will only make matters worse.

Tuesday looks to be a violent day for many in Kentucky. Perhaps the greatest threat resides along and east of Interstate 65. Let's get through today first.

MS