Not exactly the news anyone wants to hear. But some of the shorter-range model guidance is suggesting that the showers and storms developing across parts of Alabama and the Florida panhandle may set the stage for a brief window of opportunity for a bump in the risk for tornadoes to develop overnight Friday and into Saturday morning.
It is really – really! – important to note here that it still remains to be seen if this new trend within the model guidance is more accurate than past data. That is always the toughest part about forecasting. Figuring out just how reliable is the newer data aboutally is.
New Data
First we need to start with what the radar looks like right now (or at least as of 1PM).
You can see that showers and storms have already developed across parts of the Gulf, the Florida panhandle, and Alabama.
This is depicted well, but not perfectly, within the HRRR model guidance.
That means our initial conditions are decent enough for the model to build a reasonable forecast for each next step into the future.
Same with the HRW-ARF model guidance.
Both models initiated with reasonable accuracy. And so both models can be “trusted” so to speak to offer a reasonably accurate look into the future.
But because both models are different, they may offer different outcomes.
On the split above, you can see that the HRW model is more pronounced with the outflow boundary coming off the storms in Alabama than the HRRR model. This is major impacts as showers and storms develop across parts of south Mississippi.
The effects would not be on a longer timescale, but rather on a reasonably short one.
If any storm develops along that boundary or interacts with the boundary could have a higher potential to produce a tornado if storm motion was aligned along that boundary in a way that increased the low-level helicity. This would be unlikely to change the potential potency of any one tornado that develops. But it may make it easier for a tornado to form (a bit like a week ago when we had those handful of little spinny storms develop)
Around midnight, looking at the HRW data on the Karrie Meter, it shows a sharper gradient NW of Hattiesburg and down HWY 84 toward Monticello.
At that time, there isn’t much shown on the model guidance radar estimate.
But, the environment would be ripe for the development of severe weather and along a boundary capable of an increased risk for tornadoes.
If the boundary was more diffuse, and not as sharp, but it does not interact with storms until later in the evening, it may allow for slight changes in the inflow along the main line that passes through early Saturday morning. Coupled with kinks in that line, it may increase the tornado threat at that point, too. Those tornadoes would be the QLCS-style tornadoes that are brief.
The Timeline on this new threat
This would be mainly a concern between 11p and 3a. And if things are more diffuse it may linger toward 5a. And this increased risk would be for all areas of south Mississippi… if it develops.
Again, this is new data, and this threat may never fully materialize as depicted in this model guidance. However, I will say that it felt reasonable enough to produce an entire blog post about it.
…. so take that for what it is worth.
The Bottom Line
This doesn’t change the forecast. The bottom line from earlier still holds. But this is something we will be watching closely through this evening. This is mainly a wind event. And preparing to be without power for at least six hours is still a good bet. It won’t happen to everyone, but better to be prepared!
On top of the wind, there is also a concern for very heavy rain, frequent lightning, hail up to the size of golf balls and a few tornadoes – up to EF-3 in strength. If this boundary develops or not, the potential potency of the tornadoes tonight holds.
Have a severe weather plan in place. Know what you would do if a Severe Thunderstorm Warning or a Tornado Warning was issued for your area. Where would you take cover? Do you have the necessary items with you? Overnight, make sure you have a way to get alerts from the National Weather Service that will wake you up. A NOAA Weather Radio or an app for your phone that will alert you (loudly) is best.
Again, I want to stress that this doesn’t look like a knock-down drag-out tornado event. But the potential for 80mph straight-line wind is no different than an EF-0 tornado. So please take the wind seriously. Trees, most times, don’t appreciate a 40mph wind. Doubling that wind speed means there will be many trees coming down as well as a plethora of power outages.
So make plans now! That way you are ready to go if the worst of the weather knocks on your door.
Thank you for this weather update
Love your weather knowledge! It has always been comforting when you keep us updated on what is going on! Gonna miss you!