May 10: Severe Storms Possible Tonight, Daily Links

WEATHER

We started off the day with widespread showers and thunderstorms, but fortunately no severe weather.  As the morning rain moves farther to the east and dissipates, we’ll see some breaks in the clouds by midday and this afternoon.  The mid-May sunshine will push high temperatures up into the 80s:
PAUL RPM 4KM Temperature

That kind of warmth, combined with the humidity that’s already in place, will allow the atmosphere to re-charge for the potential of stronger storms this evening and tonight.  Why such a heavy emphasis on “potential”?  Because it’s far from certain that the storms will happen in our neck of the woods when the best severe-weather ingredients are in place.  The best mix of instability (to fuel the storms) and wind shear (to organize the storms) will be present this evening and early tonight…basically, until about midnight.  The Storm Prediction Center’s short-range ensemble forecast (SREF) model shows a favorable “supercell composite index” in that time frame:
SREF_SCCP_MEDIAN_MXMN__f018
But that’s meaningless unless thunderstorms actually develop to take advantage of those ingredients.  The SREF model only estimates a 50-50 chance of that happening, at the highest:
SREF_prob_combined_supercell__f018

Two of our Futurecast models, the RPM and BAMS, show storms developing along the Ohio River this evening, with some storms then developing southward into the Midstate late this evening and overnight.  They don’t necessarily look impressive on the radar simulation, but that’s right in the time frame when the severe weather ingredients will be most favorable:
RPM 9P TUE RPM 11P TUE RPM 1A WED
Both models also agree that the most widespread thunderstorm activity will be later in the night, after the best severe weather setup has diminished.  That doesn’t the mean the storms won’t be capable of becoming severe, it just means the severe threat won’t be as widespread:
RPM 3A WED RPM 5A WED RPM 7A WED

However, a third model, the high-resolution rapid-refresh model (HRRR), keeps the Midstate dry through the end of its data run at 10pm:
ref1km.us_ov
Just to complicate things, I’m not willing to rule out the possibility that storms develop ahead of schedule, in the late afternoon and early evening.  There are just too many uncertainties with this kind of loosely-organized storm system.

All in all, it adds up to a “conditional” severe weather threat: IF storms move into the Midstate, and IF they move in early enough, damaging winds and hail will be possible:
PAUL SEVERE RISK GRAPH
The tornado threat should stay farther to our north, along the Ohio River, but we’ll keep an eye out for signs of rotation, just in case.

The Storm Prediction Center has outlined a “Slight Risk” (level 2 of 5) of severe weather along and north of I-40 — we’re on the southern fringe of that risk area, so it’s possible the SPC will trim it back even farther if it looks like the storms will avoid us.
PAUL SEVERE RISK REGION
The “Enhanced Risk” (level 3 of 5) region is just off to our north, which coincides with the greatest tornado threat:
PAUL TORNADO RISK REGION
Within the Slight Risk region, SPC estimates a 15% chance of 60+mph wind gusts or 1″+ diameter hail within 25 miles:
PAUL WIND RISK REGION
PAUL HAIL RISK REGION

More scattered storms are in the forecast tomorrow and Thursday, but the severe weather threat should be lower.  Warm and muggy conditions will prevail in between the storms, until we dry out and cool down for the end of the work week and the weekend:
WSMV 7 Day AM

 

LINKS

Some weather stuff to lead off, then a smattering of other nerdiness…

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About paulheggen33

Morning meteorologist for WSMV-TV in Nashville.
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