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Posted at 12:45 PM ET, 09/02/2011

Hurricane Katia: East Coast not out of the woods


Water vapor image of hurricane Katia. (NOAA)

After weakening last night to a 70 mph tropical storm, Katia has regained hurricane intensity today with maximum winds of 75 mph. It is moving west-northwest at about 14 mph, and is still roughly 2000 miles from North America. Although it remains likely to turn out to sea late next week, some models are starting to bring Katia a little close to the East Coast for comfort.

In the most recent update from National Hurricane Center (NHC), Katia is expected to intensify to category 3 status in about four to five days as it moves west-northwestward across the warm Atlantic waters.

But as I wrote in my most recent post, Katia will have to fight off the potentially disruptive effects of a large area of dry air that nearly surrounds it now and lies ahead of its projected path (the dark and bronze areas in the satellite picture above).

We’ll see in the coming days how effectively Katia can maintain a core of deep convection near the circulation center in the midst of the apparently dry surroundings.

Wind shear, although not especially strong (in the 10-20 knot range), may also be detrimentally affecting Katia. Its asymmetrical presentation in the satellite pictures, with the out-flowing high clouds concentrated east of the circulation, suggests the storm is encountering a head wind aloft. NHC predicts the shear will soon weaken and the environment will in general support strengthening shortly.


Track guidance over next five days. View bigger. ( UCAR )
There are still plenty of unknowns regarding Katia’s future track. But more so than yesterday, the guidance (shown to the right) has tightened the spread up a bit inside of 5 days

The real question is what happens beyond then. While there remain signs from the global weather models and their ensemble systems that there will be opportunities for Katia to recurve out to sea before the storm approaches North America, there is some hint that such a turn might occur closer to the East Coast than suggested in recent days.

Huge question marks are at play here, with some of the unknowns potentially relying on what happens with tropical depression 13 and how it gets absorbed into the jetstream over the Deep South (if it does at all). As such, confidence in a potential East Coast threat from Katia is still too low to make much noise about.

Hurricane Tracking Center

By  |  12:45 PM ET, 09/02/2011

Categories:  Latest, Tropical Weather

 
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