Multiple Rounds of Storms, Severe Weather Probable
Showers and thunderstorms are currently (as of 8:50AM) moving eastward towards Davidson/Williamson Counties. A couple of these could spark up, but right now they are not expected to be severe. We’ll monitor them, just in case.
This afternoon proves to be a tricky forecast, but one to be on guard for. Based on the morning sounding from NWS Nashville, there is a bit of a “cap” on the atmosphere. What we will be monitoring is either the continuation OR erosion of that cap:
- Scenario 1: Cap stays in place for the afternoon, limits thunderstorm development until tonight.
- Scenario 2: Cap weakens/erodes and we get rigorous thunderstorms throughout the afternoon and evening. If this happens, the storms will be scattered but capable of large hail and damaging winds. An isolated tornado cannot be counted out.
After Dark/Overnight (Main Line)
This is the timeframe that we really need to keep an eye on. A line of storms capable of significant damaging winds, large hail, and some tornadoes is anticipated to develop and move through the state of Missouri by the afternoon to around dinnertime. As this same line moves east-southeast, it will have *ample* instability and good shear to maintain its strength.
The latest HRRR model has this menacing batch of thunderstorms knocking on our door between 10PM-midnight. All hazards are possible, including 70+ mph winds, large hail, and isolated tornadoes.
(Don’t pay too much attention to the morning round of storms/lack of afternoon activity on this model run. What’s more certain is the damaging wind event tonight.)
What does the NWS and SPC have to say about today’s severe weather?
SPC Day 1 Severe Weather Outlook
We are in an “Enhanced Risk”, or the “3 out of 5” category for the likelihood of seeing severe weather today. The hazard breakdown for anyone in Davidson/Williamson counties is:
Damaging Winds: 30% chance (the 45% risk is just west of us)
Large hail: 15% chance
Tornado: 5% chance
NWS Nashville says:
“Well, I wish I could say the models lined up better over the past day to increase confidence on timing and magnitude of thunderstorm potential this weekend. Unfortunately, models have not only changed their own solutions, but still are quite different with timing of storms this weekend.”
Today’s Bottom Line: Embrace Uncertainty and Have A Plan
Anytime after lunch could be eventful. A few notes to make regarding the Memorial Day weekend:
- Camping in middle Tennessee? Will you be outdoors today/tonight? It is highly likely that a strong-severe thunderstorm could ruin your festivities. Keeping this in mind, take time to prepare now…even if the worst conditions hold off until later tonight.
- Have a safe place to go. Mobile homes will not fare well with 70+ mph winds. A sturdy structure, away from windows, and on the lowest level will be your best protection from severe weather.
- Traveling? Use radio outlets and smartphones to your advantage. Also, avoid parking under an overpass for protection. Preferably, if you see or know about approaching storms, pull off the road, find a sturdy building, and wait it out.
- Lightning and human activity outdoors do not mix well (especially if you’re boating). Even without severe storms, lightning poses a life-threatening risk. “When thunder roars, go indoors,” and remain inside until 30 minutes after the last rumble of thunder.
Additional changes to this discussion are expected later today. We will stay on top of the changing conditions, especially over at @NashSevereWx on Twitter.
5-Day Pollen.com Forecast
Categories: Forecast Blogs