Sunday, September 11, 2011

Extratropical Storm Katia, Tropical Storms Maria and Nate: September 11, Update A

First, I couldn’t let this day go without mentioning the topical events a decade ago that changes the world we knew.  I remember visiting the WTC on my first trip to the US (and many times after that) and marveling at the little ant-cars zipping around on the streets below. I remember where I was when it happened, as I’m sure everyone does. I remember the surreal and eerie silence in the days that followed, including in the skies. I know some of you lost family and friends in those events, and I know many more were affected in some manner or another. My thoughts are with you on this day.

But now, back to the topical tropics of today and the lack of silence in the skies

Extratropical Storm Katia
She’s still on course for the northern British Isles tomorrow. Warnings to be prepared for windy and wet weather have been issued. I don’t see too much rain left in Katia, but she’ll definitely be a windy. Don’t bother with your umbrellas.

Tropical Storm Maria
Maria’s convection increased a lot yesterday, and she’s beginning to look like she has a better defined center to the northeast of the VIs. Most of the convection is out in the Atlantic  too. As Tom on St. Thomas said in an email (at 3-something am!), they will get away with it lightly on the VIs.

She’s officially at 19N, 63.7W heading NW at 13mph. I agree with the forecast track, which keeps her away from the US. However, it might get a bit wet and windy on Bermuda (and the surrounding seas might be a tad on the choppy side… anyone going on a cruise out there perchance?).

Winds are currently 60mph, so she’s a mid-intensity Tropical Storm (range: 39-73mph). I agree with the NHC that she will remain a Tropical Storm for the next day at least. Although her circulation is good in the lower troposphere and water temperatures are 29-30 deg C (with water warmer than 26 deg C in the upper ~75m of the water column), wind shear is quite strong and blowing from the southwest. This is very clear in the satellite image of water vapor, which shows a better defined edge on the west side and a stream of clouds on the north and east side – she’s a bit lop-sided:

You can also see dry air on her west side (it’s the brown section of the Water Vapor image). This will also inhibit her development.

Tropical Storm Nate
He is just about making landfall between Veracruz and Tuxpan, Mexico (about 10am EST), as you can see in the visible satellite image:

His center at around 20.2N, 96.7W and he’s moving generally westward at 10mph. Winds are officially 45mph (central pressure 1005mb), so he is a very weak Tropical Storm. There is hardly any rainfall in this system. I expect he’ll be a Tropical Depression within a few hours of landfall (by tonight).

Cynthia from Maryland asked why they don’t show a 5-day forecast cone on the 5-day forecast plot. This is because they only show the forecast cone until the point when the storm is forecast to dissipate. If it is dissipating within 5 days (or 3 days), they will show the cones on those plots, but for fewer days.

Later gators! (and all other college football teams. Sigh. ;-))

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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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