Monday Morning Update on TD 26

October 5, 2020

Note: TD 26 was upgraded to Tropical Storm Delta as I was writing this. While I included the correct forecast map showing the change, I didn't notice the change and thus my discussion refers to the storm as TD 26 throughout.

This morning I've had a chance to take a better look at Tropical Depression 26. The biggest change overnight has been a fairly large shift to the east for the later portion of the forecast track. The storm is expected to head northwest through at least midweek but Gamma could cause a jog to the west at some point. The NHC seems almost surprised at how good the track agreement is between the models. This is good news in light of what we've seen with other storms. There's still some uncertainty on where a strong core will form, which is expected sometime today, and also uncertainty regarding how 26 will interact with Gamma. Both of these could cause shifts in the short term track. Beyond midweek an approaching upper level trough will cause 26 to turn north and then northeast. Where 26 is when this occurs will determine the landfall point.

The intensity forecast is about the same, which shows the storm achieving category 2 strength by day 3 but then weakening prior to landfall. Near shore the Gulf has cooled a bit and this combined with the possibility of increasing wind shear is expected to cause the storm to weaken. There are a few caveats to this however. First, if TD 26 gets its act together quickly today, we could see some rapid strengthening before it has even reached the Gulf. If it can form a good core soon there's not much to limit it in the Caribbean. Second, if it is moving fairly quickly when it reaches the cooler water in the northern Gulf, it may not be impacted much by the lower temps. Third, if there is wind shear, the storm will likely be moving with the shear, this can lessen or even negate the effects it could have on the storm if the shear isn't very strong. The good news is that this morning I'm not seeing any strong model signals that show an intensity above the NHC forecast but we need to watch how this evolves.

Unfortunately the central Gulf Coast is going to be impacted by yet another hurricane. It'll be another day or two before the cone at the landfall point starts to narrow down so if you're in the cone start thinking about preparations. Keep in mind the cone only covers 2/3rds of historical track errors so a track outside the cone is always possible as we saw with Sally. We will see the track bounce around like always but I don't expect any major shifts, we all know how quickly things can change though.

That's it for this morning, have a good week and stay safe.

Chris