With Eta back over water, threat to Cuba and Florida increases

Tropical Depression Eta has re-emerged over the very warm water of the western Caribbean and is fully expected to strengthen back to a tropical storm later today.  It's centered about 60 miles east of Belize and 120 miles north of Honduras. The bulk of the thunderstorm activity associated with it is displaced to the east of the center as of this writing and satellite image below.

Model guidance continues to show the storm tracking northeast toward Cuba, reaching the island on Saturday-Sunday. Beyond that, some impact in south Florida is basically inevitable on Sunday-Monday. The hazards definitely include heavy rain with widespread flooding, and could include sustained tropical storm force winds (even a slim shot at hurricane force winds). Always check https://www.nhc.noaa.gov/graphics_at4.shtml?start#contents for the most recent information.

In this map, track forecasts from several dynamical models, ensemble means, consensus, and the NHC are shown. Keep in mind that these evolve with each new run, and that these are only the center lines of the track... impacts extend quite far from the center.

Tropical storm force winds could arrive in south Florida by Sunday evening, even if the center of the storm remains well south -- it is a large circulation and the stronger portion of it will the northern half. At this point, given the normal uncertainty in intensity forecasts 2-3 days in advance, a low-end hurricane cannot be ruled out in south Florida either.  For perspective, Irma in September 2017 produced "only" upper-end tropical storm conditions in the urban corridor of southeast Florida.

Beyond Monday, Eta is forecast to enter the Gulf of Mexico where environmental conditions are unlikely to nurture intensification, but given the large number of tropical cyclone landfalls along the Gulf coast this year, this is certainly not welcome news.

The official hurricane season ends on November 30, but active years like this don't always respect that artificial bound, so stay tuned.  Elsewhere across the basin, there is no hint of new activity in the foreseeable future... but if and when the time comes, the next name on the list is Theta.

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Eta inland, but may have Cuba and U.S. in its future

Since Monday morning's update, Eta did indeed continue to rapidly intensify, reaching an upper-end Category 4 hurricane that slowly drifted in to make landfall in Nicaragua on Tuesday afternoon.  It has expectedly weakened significantly over the mountainous terrain of Nicaragua and Honduras and is now a very disorganized tropical depression centered over Honduras.  The question is: what happens next?!

As of Thursday morning, Eta is a sprawling and struggling tropical depression... in fact, perusing some surface observations and satellite data, it's hard to even identify a surface center anymore. But there's at least a defined mid-level circulation. Whatever is left of Eta is expected to drift toward Belize in the coming day and the center should be back over warm water by Friday morning -- at which point it could start re-organizing. But will it? Probably.

A deep trough over the central U.S. will guide the storm northeast toward Cuba and then toward the Gulf of Mexico and/or Florida.  It's difficult to say anything meaningful about the intensity at that point because that all hinges on how quickly it rebuilds on Friday-Saturday. But one thing that is shaping up to look like a big threat is extremely heavy rain over Cuba and south Florida.  This 7-day forecast rainfall accumulation map (Thursday morning through next Thursday morning) shows some rather high values from West Palm Beach down to Key West! Some locations in there have already had among their wettest years on record.

Taking the latest NHC forecast as-is (there's a lot of uncertainty), tropical storm conditions *could* arrive in south Florida in the Sunday evening to early Monday morning timeframe, but heavy rain will begin well before that.  This forecast will definitely evolve, so Cuba and south Florida: pay close attention to updated forecasts at https://www.nhc.noaa.gov/graphics_at4.shtml?start#contents

Addressing the uncertainty... there's still quite a bit of spread in model guidance. Regarding south Florida, I would not rule out a slim possibility that Eta could visit as a hurricane, though a tropical storm or less is far more likely. And some models bring it north much faster, with a closest approach early Sunday; while others are slower and have a closest approach on Monday afternoon. Be prepared and alert.

These two ensemble runs from the European and American models show relatively good agreement in the next 3-4 days, then rapidly-growing spread 5-6 days out, and huge spread 7-10 days out. So don't take any long-range forecast literally; there's a lot of uncertainty!

South Florida has had just one known hurricane encounter during November, and that was November 4, 1935.  But there have been a few tropical storm encounters during November, the most recent being Mitch on November 5, 1998.

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Hurricane Eta rapidly strengthening before Nicaragua landfall

Since my previous update on Friday morning, the wave in the eastern Caribbean was upgraded to Tropical Depression 29 on Saturday afternoon, then to Tropical Storm Eta on Saturday night. This made it the season's 28th named storm which ties the 2005 record.  Then, on Monday morning, it was upgraded again to Hurricane Eta, the 12th hurricane of the season.  It is less than a day from making landfall on Nicaragua.

It is getting organized in a hurry now... this swath of microwave satellite data from earlier today reveals the precipitation structure under the cloud tops, and there's most definitely a compact eye and eyewall in there. It's not out of the question that this sneaks in at Category 3 intensity (it would be the season's 5th major hurricane if it does).

 Once it slams into Nicaragua tonight, it will pass over Honduras, weaken quickly over the mountainous terrain, and slow down as it loses the environmental steering currents in a few days. Aside from the immediate threats of storm surge and hurricane-force wind along the Nicaraguan and Honduran coasts, the flooding and mudslides caused by heavy rain are a major concern in the entire region. 

It's that slowing down so close to the western Caribbean powder keg that actually presents some challenging uncertainty. For the past few days, long-range global models have been indicating that Eta might not simply dissipate over Central America. It (or its remnants) could eventually get tugged northward, back over the steamy water in the western Caribbean, and toward Cuba in a week or so.

Here is what such a complicated scenario looks like at the moment. The left panel is from the 50-member European model's ensemble and the right is from the 20-member American model's ensemble. Both have tracks displayed out to 10 days where possible (240 hours). Both agree on the track into Honduras, and the slowing down. Then, the majority of members from both turn the storm north in 4-5 days, followed by a re-intensification and track toward Cuba. 

Should that happen, the door is open for it to enter the Gulf of Mexico, hit south Florida, or pass further east over the Bahamas sometime early next week. But first, we need to see if it survives its encounter with central America.

Only three prior hurricane seasons are known to have had 12 or more hurricanes: 2010, 2005, and 1969. So with a month still remaining in the official hurricane season, this is quite impressive.

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