I think it is a funny coincidence that the one tropical system with the name that is an acronym for “estimated time of arrival” is the tropical system that is taking the most indirect path to a final destination as possible.
Guy 1: What is the ETA on Eta?
Guy 2: No idea, it is taking its sweet time.
Guy 1: Places to go? People to see?
Guy 2: No, it looks like its bored.
This storm is wandering around like its girlfriend took it to Joann Fabrics. It looks about as happy, too.
Right Now
Jokes aside, overnight, there was an increase in convection around the center of the system and it also did a good job at shielding its center from the dry air that is now over nearly half of the Gulf of Mexico in the mid-levels of the atmosphere. The system has slowed down and is likely starting to make the turn back north.
CURRENT STATS
LOCATION…22.7N 85.3W
ABOUT 60 MI…100 KM NNW OF THE WESTERN TIP OF CUBA
MAXIMUM SUSTAINED WINDS…60 MPH…95 KM/H
PRESENT MOVEMENT…STATIONARY
MINIMUM CENTRAL PRESSURE…992 MB…29.30 INCHES
Technical Discussion from the NHC
A significant increase in deep convection has occurred since the previous advisory this morning, including a CDO-like feature with cloud tops of -85C to -87C very near the low-level center. However, recent passive microwave satellite images indicate that the center is displaced to the northwest of the coldest cloud tops due to modest northwesterly mid- and upper-level vertical wind shear. The initial intensity has been increased to 50 kt, which is based on an average of Dvorak satellite intensity estimates of T3.0/45 kt from TAFB and T3.5/55 kt from SAB.
Although the initial motion estimate is 360/02 kt, Eta has essentially been stationary for the past 9 hours or so. Radar data from Casablanca, Cuba, and satellite fixes suggest that Eta has been making a small cyclonic/counter-clockwise loop within the larger gyre in which the small center is embedded. Until the gyre breaks down or moves northward, there will be little poleward motion by Eta today. By tonight, however, the global and regional models are in good agreement on a broad mid-tropospheric trough moving eastward across the central and eastern United States, which is expected to erode a subtropical ridge to the north of the Eta, allowing both the larger gyre and Eta to move slowly northward. This steering pattern is expected to continue through about 72 hours.
Thereafter, the model guidance diverges significantly between motions ranging from westward (GFS/GFS-ensemble) to northward (ECMWF) to northeastward (COAMPS-TC). The 96-120 hour motions are directly related to the strength of the cyclone, with a much weaker Eta forecast to move westward and a stronger hurricane solution moving northeastward. The latter scenario seems unlikely given that the vertical shear is forecast to increase from the northwest and west at more than 25 kt, which acts to weaken Eta and also impart a slight eastward tug on the system. As a result, the official forecast track calls for Eta to basically move slowly northward through the 120-h forecast period and gradually weaken into a shallow cyclone that drifts northward. The new NHC track forecast is similar to the previous advisory track, and lies close to a blend of the consensus models TVCA, NOAA-HCCA, and the Florida Superensemble (FSSE).
Eta is expected to remain in a low-to-moderate vertical wind shear environment and over warm SSTs of 27-28 deg C for the next couple of days. Although the surrounding environment is expected to be somewhat dry, the other two favorable environmental factors should allow for some strengthening into Thursday, Thereafter, increasing shear from the northwest and west, along with drier mid-level air and cooler SSTs are likely to cause Eta to weaken. The rate of this weakening remains uncertain, and depends heavily on how much Eta re-intensifies over the next couple of days. The new intensity forecast is essentially the same as the previous advisory, and is a little below the consensus models IVCN, HCCA, and FSSE, all of which make Eta a hurricane again by 36 hours.
Model Data
The model data, to date, has been a bit all over the map. Literally. The spaghetti plots from yesterday afternoon looked like this:
There isn’t a lot of value, at first glance, from that data. Instead, meteorologists have to take a step back and assess the entire ‘big picture’ situation to make an estimation on track, instead of relying solely on the data plots.
That is, likely, how the NHC continues to forecast Eta. As today’s spaghetti plots aren’t much better.
However, there are a few pieces of info we can pull from the spaghetti data that is helpful.
There is a westward tug between 48 and 96 hours
Notice that each spaghetti plot shows a bit of a tug to the west or northwest between 48 and 96 hours. Knowing the big picture, that a cold front and trough are set to move through the region, that gives us an idea that after it passes, the ridge of high pressure that will settle in behind it will have a nudging influence on the storm. And that nudge will be back to the west.
How much? How long? How far? That is all still to be determined, but it is something we should watch for.
HWRF & HMON move the storm at different speeds
The HWRF and HMON models are the two hurricane models that meteorologists lean on when forecasting the tropics. While these aren’t perfect, and have their own biases and issues, they are helpful. Often times they show slightly different outcomes. In this case, the outcomes are drastically different. The HWRF has Eta in North Carolina bty Sunday. The HMON still has the system in the Gulf.
Which one is correct? Well, remember that model data isn’t always about being 100-percent accurate, it is called ‘guidance’ because we use it as a guide, not as an answer. And this guidance suggests there is still some question about whether or not the system gets pulled into the trough or not.
Late season storms are complicated
The models are struggling due to factors that they often don’t have to navigate. Not their fault. But, even with the data from the Hurricane Hunters, sometimes these models are struggle. This is a prime example of that.
As for the intensity guidance, I think this is going to be dependent on a lot. Including water temperatures. Right now, Eta is sitting over some of the warmest waters in the Gulf. So unless it gets its act together quickly, it won’t ever.
As you can see the cooler water temperatures have taken over most of the Gulf of MExico. While there is still a path north over warmer waters, eventually it will run out of steam – literally.
Because of this, the model guidance for intensity shows some strengthening, but eventual weakening of Eta before landfall.
Bottom Line
Right now the forecast is for Eta to be a Tropical Depression at landfall. So widespread hurricane-force conditions are highly unlikely. Even localized spots of hurricane-force conditions are unlikely. This looks to be more of a heavy rainfall, gusty wind and tropical tornado-producing event.
Where is it going? Specifically, we don’t know yet. Generally, I think my map from the other day still holds.
It looks like Eta will move north between the red lines.
Hang in there, friends. The good news is this isn’t looking like a catastrophic wind event for anyone. It also doesn’t appear like storm surge will be the main concern, either.
Rain, potential flooding, and some gusty wind looks to be the main threats from Eta. And the potential to add some atmospheric torque to help spin up a few tornadoes, too.
Figuring out specifically where it will go will be what we are doing in the coming days.
