WHAT: A strong/severe storm or two, with gusty winds being the main threat. A damaging wind gust is possible with any storm.
WHEN: Midnight to 4:00 am timeframe (a few storms could develop well ahead of these)
I just wanted to give everyone a heads up on some storms headed our way for the overnight hours. This is not a widespread severe weather event, but one or two storms could certainly be on the stronger side. The NWS Nashville just sent out a special briefing on this situation, and I agree with their assessment that storms should be much worse in an around Nashville from this, since they did not experience the storms and rain that we did today. Their atmosphere is, therefore, much more unstable.
A severe t-storm watch may be issued in the coming hour for parts of Middle TN. I’m not sure that will include the plateau. I’ll keep you posted.
The Storm Prediction Center has upgraded parts of Middle TN to the slight risk for severe weather. Here on the plateau, we remain in the marginal risk. A description of what that means is provided below. Storms are expected to weaken as they encounter our more rain-cooled, stable airmass form storms earlier today.
All day, many of us have tracked a complex of very severe storms across the Midwest. These complexes are called derechos, which is a Spanish word for “straight ahead”. That comes from the fact that much of the wind with these complexes produce is straight-line winds. These complexes can go for hundreds of miles, just as today’s did.
We’re not going to be directly impacted by today’s derecho, but the atmosphere behaves like a fluid and all those storms with this massive complex have sent “ripples” through the atmosphere. Those ripples can travel far and wide, like the ripples on a pond after a stone is tossed into the water. Whenever we’re as warm and humid as we are tonight, it doesn’t take much to trip off a storm.
The radar imagery below shows what’s left of the southern flank of the derecho now. It’s losing steam, for sure, but I circled examples of the “ripples” I’m talking about. Those are outflow boundaries and new storms fire on these “baby cold” fronts that shoot ahead of the line with rain-cooled air behind them. I have little doubt that process will continue generating storms right onto the plateau later tonight. A few of those storms could be strong, with gusty winds and frequent lightning.
I’ll keep an eye on things. Again, this is not a widespread severe weather event and it is encouraging that storms have, overall, showed a gradual weakening trend over the past hour or so.
My severe weather concern is on the medium side of things, mainly owing to this being such a late night event. The main threat is a damaging wind gust.