Monday, September 17, 2012

Tropical Storm Nadine & a comment on the NHC advisories and storm classification: September 17, Update A

“There can be only one.” TS Nadine, the Highlander. (It’s a reboot). ;-) I should have travel days more often… I agree with the NHC today! J

TS Nadine is the only thing to watch out there today (as far as Tropical Weather goes), and even she’s been downgraded to a Tropical Storm from yesterday's hurricane. Officially she is still a strong TS with winds of 65mph, central pressure 987mb. She’s at 33.5N, 34.5W, heading NE at 12mph. I agree that she’s a strong TS because although her circulation is still good in the lower half of the troposphere she doesn’t have much convection, as you can see in this infrared satellite image:

In fact there was more rainy weather over the northern Gulf states today than there is in Nadine.   She’s still heading towards the Azores, getting into that vicinity by Thursday. I agree with this too… and all this being nice and agreeable doesn’t end there! (I hope you are sitting down for the next bit, maybe with a good drink in your hands, because I’m about to defend the NHC! ;-))

<Soap box alert> I read something today ( in which the NHC had to defend their advisories, essentially because some who convey this information to the public say the information the NHC releases is too difficult to grasp. I think the NHC should leave their advisories alone; they are perfectly understandable to trained meteorologists. The official advisories are for a range of audiences (as mentioned); they are not written for a general audience (otherwise why have TV broadcasts, fancy graphics, or completely (ahem) fabulous and witty (ahem) blogs? ;-)) During storm situations I imagine it is pretty stressful in the Hurricane Center and they need to consider advisories that address many groups and countries, not just the general US public. The onus in accurately translating the technical information that the NHC releases should be on those who make a living in communicating this information to the public. The NHC’s focus should be on forecasting.

The other piece of this report tackles the problem that storm intensity classification depends solely on the wind speed according to the Saffir-Simpson scale, and yet quite a lot of damage is caused by water (storm surge, flooding, convection). I agree that this could do with some adjustment but I am not sure that simply changing the Saffir-Simpson scale is the best answer. Other solutions include better information to convey the importance of storm surge and flooding (as written in the piece), or maybe we simply need another (clearly defined) scale for surge? Storm surge can vary greatly between storms even though their intensity is the same- it depends on the size of the storm, how fast it is moving, the angle of approach to the coastline, the shape of the coastline, the bathymetry/topography etc. The NHC received no end of criticism when Hurricane Ike was approaching Galveston and they said it meant certain death if people didn’t evacuate. Referring to some sort of water-related scale would remove some of that drama. After all… we know a cat 5 means pretty much ‘total destruction’ (from the winds).

That is my comment in which I defend the NHC. This is a rare event and it doesn’t mean I agree with all their forecasts and analysis of storms of course. And in case you are wondering… I’m sure the aliens will return the usual critical, and yet very funny and modest me back to earth soon. ;-) <end Soap Box alert>

Tally ho!

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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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