by Judith Curry
The only thing crazier than the U.S. election is this morning’s hurricane forecast.
I have no words re the election. For a diversion, here is my hurricane forecast for Eta.
Summary: current: TERRIBLE. forecast: CRAZY
Latest from NHC (7 am EST): 145 mph max sustained winds, min pressure 936 mb, moving WSW at 4 mph
Eta is a monster, about to make landfall in Nicaragua. Currently undergoing eyewall replacement cycle which has dropped the intensity somewhat (it came close to Cat 5). This will be horrible for Nicaragua.
The Cyclone Damage Potential is off the charts: Not only extremely high wind speed, but moving slow. I can’t remember the number for Dorian, will look that up later. But I think 9 is the highest I’ve seen for an actual landfall. (Hurricane Katrina was a 3.8)
The worst is far from over. The first thing I saw this morning, from ECMWF. The red dots are Major Hurricane. This looks like the West Pacific, I don’t think I’ve ever seen anything like this in the Atlantic. The ECMWF might be going crazy in terms of intensity (more below).
Regional intensity probabilities from CFAN’s ECMWF-based synthetic tracks.
Here is the near term track forecast, from everything that is on the landfall impact tool. While some tracks take a dive in Central America, most make a NE turn towards Cuba, reaching Cuba in 4-6 days. ECMWF wants to quickly redevelop into a MHR; the HWRF and NHC keep Eta at a tropical storm; with GEFS redeveloping to a hurricane.
Beyond 5-6 days, it looks like the tracks that survive that long are headed towards the eastern Gulf coast. For the last several runs, GEFS Ensemble Mean takes it to Tampa, but this is 9-10 days where there is little track forecast skill.
From the ECMWF ensembles, 52% make it into the Gulf of Mexico, and 53% from the GEFS.
Here are the synthetic track pdfs:
Here’s another forecast, the likes of which I’ve never seen before. ECMWF keeps this near a Cat 3, the GEFS keeps this near the Cat 2 border, and the NHC quickly drops off to a TS or lower. The GFS/GEFS emerges back into the Caribbean more quickly than the ECMWF.
BTW, re rapid intensification, CFAN’s RI index shut down after the 18Z forecast yesterday.
After landfall in Central America, there are mountains and I would normally expect Eta to be torn apart quickly, which is what NHC is predicting. But there is a piker that lends some credibility to the global model forecasts. This is the 200 hPa velocity potential forecast for 11/02 – 11/06. Dark green means that the large-scale dynamics support strong rising motion over Nicaragua, indicating the atmospheric dynamics do support maintaining the intensity. So the GEFS/GFS intensity forecasts could be about right (ECMWF looks unbelievable to me, but it’s 2020).
If Eta really does collapse like the NHC predicts, there may be nothing left to redevelop. But conditions are sufficiently favorable in the Caribbean for the next ~10 days that there is no way we are off the hook if Eta somehow dies in Central America.