The
105°F heat index readings are going away today. This weekend should be
very normal for this time of year with beautiful summer weather. But the
transition from miserable to normal isn’t going to happen easily. A round
of severe weather is going to explode today across much of the eastern half of
the nation, primarily in the Ohio Valley and into New England.
We
have just about all the ingredients to make the cake that we need.
Instability is VERY high (up to 4,000 joules per kilogram!) The surface
is being heated by the sun uninhibited by clouds. Temperatures are in the
90s to near 100 by afternoon, creating strong lapse rates. There is
decent wind shear of 40-50 knots. We’ve got lift in the form of a cold
front approaching the area. Dewpoints are running in the 70s so water
vapor content for fuel is plentiful. Basically, this is a prime recipe
for severe thunderstorms.
Here
is the current wind damage outlook from the Storm Prediction Center:
As
you can see, northern sections of Kentucky, basically north of I-64, are in the
30% range. Cincinnati is in the hatched area, where “significant” wind
damage may occur. Anyone inside the red zone on this chart needs to pay
special attention to the weather today.
I
think the timeframe we’re looking at is from about 17:00 (5pm) through
midnight. Many of the models are showing convection holding off
here until well after dark. The Hi-Res NAM doesn’t really get things
going here until 2:00 tomorrow morning. But I think that we’ll see a very
active squall line threatening Kentucky before sunset tonight.
In
this setup, tornadoes are not a major threat to Kentucky. Wind damage and
flash flooding will be the biggest problems here. Remember, the #1 killer
in thunderstorms is WATER. Floods kill more people annually than
lightning or twisters. If you see running water across a roadway, do not
drive through it, even if you have a Jeep. It’s tempting, I know.
But don’t do it. Moving water has significant power.
Keep
the NOAA weather radios on today and keep your eyes peeled. We had storm
fatalities in KY last week...let’s have zero this week.
-Shawn
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