Who is with me? A vote for dissipation is a vote for sanity!
I’m being told, ‘that isn’t how any of this works, Nick’
Drat.
Well, then, let’s get right to the update…
From the NHC
Tropical Depression Eta is pretty disorganized. It almost looks like just a large Central American Gyre at this point. There is a left over low level center in there somewhere. And the mid-level area of rotation is broad – but there.
FORECAST POSITIONS AND MAX WINDS
INIT 05/1500Z 15.1N 87.8W 25 KT 30 MPH…INLAND
12H 06/0000Z 15.7N 88.0W 25 KT 30 MPH…INLAND
24H 06/1200Z 16.8N 87.6W 25 KT 30 MPH…OVER WATER
36H 07/0000Z 17.8N 86.2W 30 KT 35 MPH
48H 07/1200Z 19.0N 84.5W 35 KT 40 MPH
60H 08/0000Z 20.1N 83.0W 45 KT 50 MPH
72H 08/1200Z 21.3N 81.2W 50 KT 60 MPH
96H 09/1200Z 23.0N 80.0W 50 KT 60 MPH
120H 10/1200Z 24.0N 83.0W 55 KT 65 MPH
TECHNICAL DISCUSSION
Eta remains disorganized this morning, as visible imagery suggests that the circulation has become elongated and that multiple vorticity centers may be present inside the larger cyclonic envelope. The center position for this advisory, which is over northwestern Honduras, is closer to convection in the northwestern semicircle than was the case 6 h ago, so the cyclone is being maintained as a tropical depression at this time.
The initial motion is a somewhat uncertain 305/8 kt. Eta or its remnants should move generally northwestward today, then turn northward tonight. From 24-72 h, the system should move northeastward in response to a developing mid- to upper-level trough over the central and eastern Gulf of Mexico. From 72-120 h, the trough is forecast to become a closed mid- to upper-level low in the vicinity of western Cuba, with the center of Eta likely to turn west-northwestward on the north side of the low. While the global models are in good agreement with this synoptic evolution, there is a significant spread in the forecast tracks between the fastest and farthest east GFS and the slowest and farthest west UKMET. The new forecast track lies between these extremes in best overall agreement with the ECMWF and Canadian models, and it calls for the system to be near western Cuba and the Cayman Islands in 60-72 h, and then be over the southeastern Gulf of Mexico by the end of the forecast period.
Little change in strength is expected before the center moves back over the Caribbean, but there is still a chance that Eta could degenerate to a remnant low pressure area later today if the convection does not persist. Intensification is expected over the warm waters of the Caribbean Sea from 24-72 h, although this may be slowed by southwesterly shear caused by the aforementioned trough. As the trough cuts off near or over Eta between 72-120 h, the global models suggest that the system could strengthen while acquiring at least some subtropical or hybrid characteristics due to upper-level cold air entrainment. The new intensity forecast is little changed from the previous forecast, and in the latter part of the forecast period it lies near the intensity consensus. It should be noted that while Eta regaining hurricane strength cannot be ruled out, there is little support for that in the current guidance.
Model data
The model data continues to struggle a bit with Eta as it continues to weaken and lose organization over land. While the model data is still pretty consistent and the forecast from the NHC hasn’t changed drastically, it isn’t as good as it could be if Eta were, for example, over water and the Hurricane Hunters could fly through the storm. Or if the low-level center and mid-level center were still stacked and easily identifiable within the modeling.
It is a good news / bad news situation, though. The bad news is that the models are struggling. The good news is that it is weaker and more disorganized. So, you have have to take the good with the bad here, I suppose..
To the data!
As you can see the model guidance still moves Eta back to the northeast toward Cuba and then flips it back toward the Gulf of Mexico. The path hasn’t changed much. But the timeline has really slowed down. Originally, the thought was it would potentially be into the Gulf by Sunday. Now the data suggests Monday, perhaps even Tuesday. The consensus between the plots above would show a slowdown of about 12-36 hours.
That slow down means more time over the warmer waters of the Caribbean. And a better chance – though, not a guarantee – that more organization and strengthening occurs. On top of that, a slow down means that the puzzle pieces we were talking about yesterday may not be all of the pieces. Sicne troughs / cold fronts swing through the southeast in November about once every four to six days, a slow down of up to 36 hours (maybe longer) means that a front may swing through and miss Eta. Leaving the door open for it to go somewhere between one front and the next.
A lot of hypotheticals in there, but that is the biggest problem with late season storms. The puzzle pieces aren’t as “locked in” as they are in August.
The GFS Ensembles show a similar story.
A storm that siggles around as it lifts north toward the Gulf. Since this time yesterday (the graphic below) I would say it is doing much better.
But there is still a lot of ‘play’ between the individual members (lines) of the Ensemble. Which means the number of possibilities remains pretty large.
The Bottom Line
Okay, with all that being said, I know what a lot of you are thinking, “C’mon Nick, just tell us what this means for the Gulf Coast”
I can’t. Because I honestly don’t know. We are going to have to hang in there for another few days while this thing gets back out over the open waters and tries to get better organized. We will have to see how long it takes to move into the Gulf, too.
These late season storms are incredibly frustrating for us (meteorologists) because they are often not as straight-forward to predict as their mid-summer brothers and sisters.
