In an unfortunately familiar saga for the 2020 hurricane season, Eta is rapidly organizing and intensifying as landfall approaches. Over the last few hours, the storm has taken advantage of the very warm SSTs, low shear, and favorable atmospheric outflow channels present over the southern Caribbean Sea that I discussed yesterday. A fierce, symmetric CDO with a ring of cloud tops between -75°C and -85°C surrounds a nearly cleared, very small eye, and the NHC recently officially declared the storm’s sustained wind speeds to be 110mph. Eta looks like a category 3 or 4 hurricane, and is probably not too far from getting there.Link: https://weather.us/satellite/844-w-160-n/top-alert-superhd-15min/20201102-1540z.html#play-0-12-5 The conditions over the storm look to remain favorable for intensification through landfall. Eta is imbedded in a very moist envelope that spawns much of the Caribbean, as evidenced by broad convection spanning hundreds of miles from the storm’s center. The storm looks to have a healthy outflow band to the north, evidenced by clockwise-moving cirrus clouds stretching in that direction, and another may be developing to the south. And the ocean ahead of Eta is still quite warm, with that warmth stretching to a great depth. Shear looks to increase marginally, but with the moist envelope and the hefty organization, it looks unlikely at the moment that it’ll be able to make a dent in the storm. Really, now that the storm has organized to this extent, it’s all systems go for continued strengthening. Of course, there is always the shot that an eyewall replacement cycle is able to crush the tiny eye before it reaches land. But time is on Eta’s side, The only thing looking to stop this storm seems to be land, which is about 20 hours away. In that time, the NHC now forecasts Eta to reach 140mph, a mid-range category 4 intensity. I could see it ending up stronger. It is of note that this will be among the strongest Atlantic storms for this time of the year, and I believe that the NHC forecast has it behind only 1999 Lenny, 2008 Paloma, and a category 5 hurricane in 1932 for the strongest storm ever so late in the season. Eta, born to break records, continues to be historic. As the midlevel high I talked about yesterday spills into the Gulf on cue, models remain tightly clustered on an increasing south of west motion for Eta. This will take it on a trajectory to landfall in northeast Nicaragua, likely near Puerto Cabezas.
Eta’s fierce intensity but relatively small size will mean local devastation where it landfalls. A concave coastal shape will help Eta produce 12-18 foot storm surges near the point of landfall, per the NHC. This is a potentially catastrophic inundation, made worse by high background tides with the full moon. Of course, the 140-mph wind itself packed by Eta will also bring devastating impacts close to landfall. As with any small, well organized major hurricane, the damage will be like that of a strong tornado where the eyewall moves ashore. For those close to the landfall location, any preparation should be rushed to completion. This is an extremely dangerous storm. Landfall will not be the end of Eta’s impacts- rather, a potentially more devastating chapter may begin as the storm slows down over Central America on Tuesday. Nicaragua and Honduras are both particularly topographically vulnerable to flash flooding and mudslides from slow moving tropical systems. When Eta meanders slowly over land, a great deal of the same tropical moisture helping the storm strengthen now will continue advecting ashore. This can be seen through HWRF modeled precipitable water, a parameter that indicates how much moisture is present in the atmosphere.
- The area sees persistent advection of new moisture
- The area sees persistent rain-creating convergence