Saturday, October 07, 2017

Hurricane Nate: October 6, Update A

Of course Nate would show up when I’m super busy! Typical. I have been watching him when I can, but between travel, celebrating birthdays (Happy year birthday Ben! J), and not having good internet access it’s been a bit tricky. Anyway, I have some ice cream and so off we go…

Hurricane Nate (as he became just a short while ago) is officially a very weak cat 1 storm with winds of 75mph, central pressure 988mb (cat 1 range: 74-95mph). This upgrade came about because a plane flew into the center and has estimated the winds to be this strong. I would say he is stronger than that. He definitely has a lot of very strong convection, which you can see in this infrared satellite imagery:
He has really grown in the last few hours - the red/gray area are very strong thunderstorms! Also, the circulation (vorticity) signal is really good throughout the troposphere – even at the 200mb level (the upper troposphere), which indicates a hurricane:  
I would estimate him to be a mid-sized cat 1 with winds of around 85mph – he doesn’t really have an eye yet, so not quite at 90mph yet. But I think there is a possibility that he will be a cat 2 at landfall if he develops an eye in the next few hours. 

He is currently at 22.4N, 86.3W, heading NNW at 22mph. Alas, his track is taking him to the central northern Gulf – the general New Orleans to Mobile (AL) area with landfall in 24 hours:
The convection is strong because he is over the Loop Current, which is part of the Gulf Stream system of currents that have very warm water that is quite deep. He is currently over water that is 28-30 deg C and the upper ~100 meters is warmer than 26.5 deg C. There isn’t much to inhibit his development until he gets to around a latitude of 26-27 deg N, when the water is slightly cooler and there is an area of some wind shear. So I would expect some more intensification until then at least, and after that he is getting close to landfall and will be inhibited from growing by the interaction there as well.  

The big thing to watch for is the storm surge - this is not going to be pretty. Nate is pushing the water onto the coast to the east and northeast of his center – which means the entire west coast of Florida and the northeastern Gulf. And because of the Mississippi delta, he will also be pushing water into Lake Borgne and Lake Pontchartrain. The levels are already rising and along the west coast of Florida and the northeastern Gulf they are over 1 ft above normal in most places, with some in Louisiana showing 2ft above normal levels.

I know it’s not been that long in time, but it’s been a jolly long time in terms of posts (what a busy few weeks!), so… <Technical Alert!> To look at storm surge, go to NOAA's Tidesonline:, click on station you want on the left side bar, or scroll down to the states and pick the state you want and then the station in that state. Here’s the current data from New Canal Station on Lake Pontchartrain:
The top graph shows the water level. In this graph, the red line is the actual observed sea level, the blue line is what the predicted water level would be because of the tides, and the green line is the difference between the two. The height of the green line gives you the storm surge level (~2 ft at the moment). The graph below that is wind speed and direction. Below that is air pressure (which you can see is still dropping), and below that is air and sea surface temperature. <End Technical Alert!>

Tomorrow is another super-packed day so I may have to resort to tweets only but I'll try and get a short something out. 

Good luck and stay safe out there my friends!


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DISCLAIMER: These remarks are just what I think/see regarding tropical storms - not the opinion of any organization I represent. If you are making an evacuation decision, please heed your local emergency management and the National Hurricane Center's official forecast and the National Weather Service announcements. This is not an official forecast. If I "run away, run away" (Monty Python), I'll let you know. 

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