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Hail, Tornadoes Possible This Afternoon/Evening

Frequently Asked Questions

1.  Is it safe for me to drive from “x” to “y”? — Keep in mind we’re only looking at two counties. If your travel takes you elsewhere, I’m not the person to be answering that question. I also am very uncomfortable telling you when you should travel. My goal is to give you the information you need, and leave 100% of the decision to you.

2.  Long-track tornadoes seem to do the most damage. If one is on the ground 30 miles away tracking forward you, what do you do? — Long tracked tornadoes wax and wane in width and intensity. If you see one coming for you, shelter in place. Do not get in your car and try to outrun or otherwise elude it.

3.  How can I report severe weather to NWS-Nashville? — Easy! Tweet it by including #tSpotter in your report. Let them know what/when/where. Geotagged tweets are most helpful, but, above all, tweet safely.

4.  When tonight should we expect the worst to be behind us? — We are hoping that’ll be after midnight, but the storm system may linger into Tuesday.

5.  What about my flight into/departing BNA? — Pilots are rock stars. They know what’s up. If they take off/land, then it’s safe. Don’t worry about it. As for delays, yeah, I think you should be prepared for those.

11 AM Update: Flooding & Other Severe Wx Concerns Continue: Watching “The Boundary”

NWS 11 AM Conference Call Slides (made for all of Middle Tennessee):

Overview

Flash Flooding Concerns:

Flash flooding is the #1 weather killer. Please don’t gloss over it. Notice the above graphic depicting a “high” risk of flooding rainfall.

This “boundary” is very interesting. The boundary is basically an area of air, stretched west to east across Middle Tennessee, separating warm/humid/unstable air to the south from cooler/less humid/more stable air to the north.

North of the boundary, the threat is less, but not zero. NOTE that tornadic storms can (and in fact yesterday they did) form along such a boundary, and then moved a county or two north of the boundary.

South and along the boundary, the tornado threat is especially high, including long-tracked and strong tornadoes.

The boundary is expected to move. If the sun comes out, it’ll likely drive the boundary north, and put us on the south side of it. Storms fire along, and south of, this boundary, so it’ll be watched like a hawk.

Storms are expected by late afternoon into early evening, so the location of the boundary at that time will make all the difference. We want to be well north of the boundary, where the storm threat is less. If we are south, along, or just barely north of the boundary, things could get pretty bad.

The following SPC outlooks (updated at 11:30 AM) speak to the specific forms of severe weather forecast, with the probabilities for each. This update appears to reflect the current trend of the boundary, hopefully, remaining south of us.

1.  Tornado – It’s hard to tell from this map, but my GR Earth software draws the northern edge of the red shaded area along HWY 96 in Williamson County.

So, if we adhere strictly to this line, the probability a tornado will occur within 25 miles of those N of HWY 96 is a 10%. This would include all of Davidson County, Brentwood, and those of you N of the Murfreesboro exit along I-65,

For those along and S of HWY 96, the probability is 15%, and of those tornadoes, the probability is 10% “or greater” a tornado will be strong, rated as an EF2 or higher.

All that said, the exact drawing of the line is largely insignificant. What’s more important is where “the boundary” is by mid/late afternoon/evening.

2.  Hail – the forecast here remains unchanged. The probability of large hail (1″+) happening where you are or within 25 miles of you is 30% (N of HWY 96) to 45% (along, S of HWY 96). There’s a 10% “or greater” probability — for both counties — that the hail will be large (2″+). Shelter your stuff.

3.  Wind — the probability of 58+ mph wind gusts happening within 25 miles of you is 30%, although the probability may be a bit less for those NW of Nashville (15%).

We will be updating you all day on this website; however, note we will NOT post ANY warnings here. Additional information can be found on Twitter @NashSevereWx. We should not be your only source of severe weather information.

A Flash Flood Watch is effective until 11 PM tonight.

We’re going to get a LOT of rain over the next 48 hours. Do not drive over water covered roads — water can move your car, and water may be covering/obscuring a washed-out road beneath it.

Current Official Hourly Observation (taken at :53 on the hour)

Current local radar loop includes live severe weather warnings

 

This website supplements @NashSevereWx on Twitter.

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