August 28, 2023
Tropical Storm Idalia has started its journey north and as of the 10 a.m. CDT advisory it is nearing hurricane strength. The storm will continue north for the next few hours and then will start making a gradual turn to the northeast. Wind shear is currently limiting intensification but that will subside soon and allow Idalia to strengthen more or less all the way until landfall somewhere in the Eastern Panhandle, Big Bend, or maybe the Tampa area Wednesday morning as a major hurricane (category 3, maybe stronger). As of this forecast no significant impacts are expected west of Apalachicola but that could change if we see a more northly track. This link from the NHC along with info from local meteorologist are your best source for expected impacts. If you want specific info for a given area just let me know and I'll get that to you.
Because of the storm's more easterly launching point it looks like locations west of Apalachicola are clear from a direct strike. Most of the model guidance has been locked into the Big Bend area for days with only a few ensemble members showing tracks west of north. While those kind of tracks are technically possible I haven't seen any indication in any of the recent discussions that the steering flow could take the storm west. So think of a straight north track as being the worse case to the west with a curve to the northeast or even the east being most likely. As late as yesterday morning the NHC mentioned that the track was still of low confidence but that was the last time I have read that kind of language.
As far as strength goes, rapid intensification of the storm is almost certain at this point. That means that we are likely to see a category 3 storm at landfall with category 4 strength a possibility. Devastating to catastrophic damage (more details at the link) from winds and storm surge will occur for those areas near and to the east of the storm center.
Unless there is a track shift to the west this will likely be my last update on this storm. With that said, I want to take a moment and discuss how the forecast evolved from a "max cat 1" on Friday and Saturday to where we are now. First, the original forecast had Idalia forming either right over or very near the Yucatan Peninsula. The expected land interaction was going to prohibit any organization and strengthening until the storm moved north-ish over open water. Instead TD 10 developed (sooner than expected I should add) over open water and then did a counterclockwise loop over water to where it is now. This has allowed it to strengthen and to have a launching point into the Gulf father south than expected. So now we have a fairly well organized storm (currently only limited by some northerly wind shear) that will track over very warm water for a longer distance. Also, it was thought that dry air and wind shear along the expected track of the storm would slow development. While some wind shear does look to impact the storm in the near term, dry air does not look to be much of a factor anymore and the upper level environment is poised to help exhaust (favorably vent, not tire) the storm and aid in intensification. As I have mentioned in the past it is these types of things that can cause a forecast to be highly uncertain until a low level center actually forms and that is where we are at now.
"I" named storms have been retired more than any other letter (somewhat by coincidence) and it looks like we may see another name retired after all is said an done. This is going to be a very impactful and life changing event for those in the storm's path.
Folks in the Panama City area should keep an eye on the track for the next day or so in case there are some shifts to the west (I would expect any to be slight). The rest of us farther west are safe I think, but personally I'm always a little nervous when there is a strong storm close to me until it has made landfall.
Chris
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