September 25, 2022
I've been waiting for Ian to decide what it's going to do before making a post. We're not quite there yet but I'll tell you what I know at this point.
The official forecast for Ian as of 11 a.m. EDT is shown below. After shifting west quite a bit yesterday due both to model shifts and shifts in the storm's position the track has been mostly stable overnight. For an excellent explanation of these things and why they matter watch Dr. Levi Cowan's (Tropical Tidbits) latest video. You can see the center of the forecast track takes the storm into the St. Marks area of Apalachee Bay early Friday as weakening category 1 or 2 storm but with quite a bit of spread in where it may ultimately end up (more on this below). Reading between the lines I think the most favored track is still east of our area but a track more to the west can't be ruled out. Ian is expected to become quite strong before landfall with the forecast calling for a category 4 storm with 140mph sustained winds in the Gulf three days from now. The presence of increasing wind shear from a trough (think front) pushing south is expected to weaken Ian as it approaches the coast. That being said, significant impacts are expected wherever Ian does make landfall.
Now let's talk about the forecast uncertainty. Really the best resource on this is the video I linked above, but I'll do my best to summarize. First it's important to understand that the cone of uncertainty shows "two-thirds of historical official forecast errors over a 5-year sample," source. Another way to look at that is one third of storms track outside of the cone. Also, note that the cone does not represent uncertainty in the models or that of a particular storm! For that we either need to look at the models or read the NHC's discussion. Here are some statements from the full advisory issued at 5 a.m. EDT: "While the models agree on the overall scenario, there are still significant differences regarding the exact track of the storm, especially after 72 hours. Even with the addition of.. [additional data]..., the spread in the guidance has not narrowed from before...With the cross-track spreading remaining between 200-220 n mi at days 4 and 5, it cannot be overstated that significant uncertainty remains in Ian's long-range prediction." And from the 11 a.m. EDT discussion: "there is still significant uncertainty in the long-range track forecast of Ian, and future adjustments to this portion of the forecast will likely be required." So while the track has stabilized some there is still quite a bit of uncertainty in the long term due to uncertainty on where the storm actually is (it's still not vertically stacked from the surface to the mid-levels of the atmosphere so the center is jumping around, although this is getting better) and future timing and strength of both Ian and an approaching trough that will be the main steering influence.
Getting into the models, the Euro and UK models have been consistent with a Florida west coast landfall. The GFS models started shifting west on Thursday with this continuing through yesterday afternoon when some of the hurricane spaghetti models started shifting west also. While there is still a group of models to the west of the Euro and UK, some good news for us in the western Panhandle is that several models in this western group, including the GFS, have shifted back to the east a bit. This is a trend I've been looking for. Yesterday afternoon I was starting to have growing concerns that Ian may be coming our way but I wanted to watch and see if the western trend continued or not. Now that the shift has stopped and even moved back east a little I'm feeling better. Even so, it may be another day or so before the track is nailed down with more certainty. Shown below are the latest GEFS, EPS (Euro), UK, and other spaghetti models.
GEFS Ensemble (GFS)
Euro Ensemble
UK Ensemble
Other Hurricane Spaghetti Models
There's not much else that needs to be said at this point. It's a good time to think about any plans you'd need to make if a storm does come our way, get some supplies, and get some gas. We'll have a clearer picture in a day or so.
Enjoy your Sunday.
Chris
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