Deep South Weather: Tropical Storm Helene forms in the Gulf, Will Likely Make Landfall as a Major Hurricane on Thursday

September 24, 2024

Tropical Storm Helene has formed in the Caribbean as of the 11 a.m. EDT advisory from the National Hurricane Center. I didn't send an email yesterday but I think all of you have seen the first several advisories from the NHC. Since the first advisory the cone has narrowed considerably (just due to inland progression, not increased forecast confidence) and the track has shifted east a bit. Helene is currently forecast to make landfall somewhere between Panama City and Tampa on Thursday as a category 3 hurricane. If you're in or near the forecast cone you should be making preparations or at the very least have a very solid plan that you can act on quickly, more thoughts below.

In their discussion, the NHC made the following comment:

"The track guidance is very tightly clustered, which would normally imply high forecast confidence. However, depending on exactly where the center forms could end up shifting the entire guidance suite in future cycles, so it is imperative to not focus on specific landfall locations this far in the future."

A few things to note about this. First, it is interesting to hear the NHC talking about where the center may form when by definition a tropical storm has a relatively well defined center... Perhaps it is not quite well defined enough yet to consider it locked in, I don't know. Second, I would not expect any very large shifts, maybe 20-30 miles at the most. This shift would be largest at the storm's center and probably not quite that much at the landfall end of track. As it is my thinking is that any shifts due to center realignment will be to the east and not the west as the strongest convection (storminess) is off to the east of the low level center so it may pull the center more that way. This can happen in the opposite direction though and currently the low level center is moving to the south-southwest with the mid level center moving to the northwest. Also, I think we may see some more shifts to the east as the model forecasts are trending that way, with many operational models still to the east of the hurricane spaghetti models. Whatever happens, I think confidence will increase a lot later today or overnight as the center completely consolidates.

Regarding intensity, the official forecast is for Helene to be a low end category 3 hurricane at landfall. In itself that would be a very powerful storm but this may be underdone and it is possible that it could even become a category 4. To make you feel better, the stronger solutions seem to be more to the east compared to the more moderate solutions. So if it does make landfall on the western edge of the guidance envelope hopefully a category 3 storm is the strongest we will see. No guarantees.

Going out on a limb here a little bit and hopefully this isn't premature, but I think everyone from Panama City west will not see the most severe impacts from Helene as I think it will continue to adjust east a bit. The one exception to this being for immediate coastal areas as they are likely to be impacted by storm surge at least to some degree. All the same, if you're near the forecast cone stay vigilant and be prepared to adjust your plans at a moment's notice. Also, if local authorities recommend you evacuate, please heed their advice regardless of what I have said.

Maps of expected impacts are below. There will likely be a tornado threat but I expect it to be to the east and later northeast of the storm center.