Sunday, September 18, 2011

Wrap-Up on H. Maria: September 18, Update A

Hurricane Maria had long gone by the time I got back to a computer on Friday evening, so instead of wrapping things up, I’ve been dawdling, pottering, sleeping, dawdling some more, eating, drinking, and pottering again. Time for some final thoughts (including a science AND forecasting alert – ooh… two for the price of one!! ;-)), then I can get back to my pottering and dawdling and another cup of tea (it’s a sleepy Sunday morning… there’s time for TWO cups of tea!).

Maria was not a hurricane as she went by Newfoundland but, in my humble opinion she was an extratropical storm (with tropical storm force winds). The Canadian forecast (from Environment Canada – the Canadian weather service) expected maximum winds of around 43mph in the St. John’s region of Newfoundland, which would mean her winds were equal to a weak Tropical Storm (range: 39-73mph), not a hurricane. (Oh by the way, in case you were wondering, more than three people do actually live north of Maine. Look on googlemaps… there are cities and towns and everything up there! ;-))

The last NHC advisory was at 5pm AST (Atlantic Standard Time, which is the time zone for that part of Canada) on Friday, when they had her as a post-tropical storm, with winds of 70mph, central pressure of 982mb, heading NE at 58mph, and that was their last advisory.

Tom from St. Thomas raised a very good point after my previous update. He asked that if the winds were 80mph, and she was moving forward at 43mph, does this mean that the winds in some parts of the storm were approaching 123mph?

<Science AND Forecasting Alert!> The maximum winds were 80mph, not 123mph, because the NHC already allow for the forward motion in their 80mph wind estimate. If Maria had been stationary, her winds would be around 37mph (not even a Tropical Storm!). But because she was moving forward at 43mph, that was added and the highest winds are what we get as the storm’s winds in the advisories.

These winds are not evenly distributed around the storm. In the Northern Hemisphere, winds move around the storm center in an anti-clockwise manner. So generally, the right side of the storm has stronger winds than the left side of the storm because those winds are in the same direction as the movement of the storm. Here is a simple picture to show this (thanks to the NOAA/NHC website for the graphic,, which addresses this question):

<End of Science AND Forecasting Alert!>

There are currently three yellow blobs on the NHC map… they aren’t very well formed, so I’ll let them cook for another day or two before writing more. See yas later!

Blogs archived at
Twitter @JyovianStorm

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.

No comments: