Weather! Irene approaches Bahamas, US coast

Hurricane Irene has intensified and continues to track towards the US.

August 23, 2011; 4:01 PM • by Weather Dan

Irene is pulling away from Hispaniola now, headed toward the Turks and Caicos Islands and the Bahamas, all of which are now under a hurricane warning.

No advisories have been posted yet for the United States mainland. However, officials on Ocracoke Island, on the Outer Banks of North Carolina, have issued evacuation orders. Visitors are asked to leave beginning at 5am on Wednesday, and a mandatory evacuation order will go into effect at 5am Thursday.

The talk of the last 36 hours has been about exactly where Irene is going. Many of the models are hugging the coast, especially along the Outer Banks, and either forecasting landfall or a close scrape. Talk has been ramping up, and people definitely need to start preparing now.

That being said, we’re still 4-5 days away from Irene’s approach to Virginia. The average track error for storms in that range is 200-250 miles, which is not a small number by any means. For comparison, the straight-line distance from Norfolk to Roanoke is about 200 miles. That’s still quite a large area.

Irene is also a very large storm. Tropical storm-force winds extend out 200 miles from the Irene’s center in all directions, which means we are going to feel the effects from the storm while the center is quite a distance away, and will continue to feel them after the eye passes.

The afternoon forecast track from the National Hurricane Center. Models are starting to come into in agreement about a close approach along eastern North Carolina and into Virginia over the weekend. Assuming that Irene sticks to this track (and at this point, that is still a rather large assumption), we can expect to start seeing cloudcover by Friday evening as the storm approaches the coast, and winds will pick up through the day Saturday, possibly exceeding tropical storm force (39 mph). Rain will be plentiful, though it’s hard to say exactly how much quite yet. I would expect some flooding in areas that are quick to flood during heavy rains. Some places, especially east of Richmond, will likely have to deal with both coastal flooding as the storm approaches and then river flooding after the fact. Rain and wind will bring down some trees and powerlines, and I would expect to see plenty of power outages across the region. Some of Irene’s rain bands may also have some embedded thunderstorms, which, if strong enough, could spawn tornadoes.

I’ve said it before and it bears repeating – now is the time to prepare. Make sure you’ve got enough food and water to handle a couple days without power. Flashlights, a portable radio, batteries, and other accessories may be necessary. You don’t need to panic (especially after today’s quake), but you need to think about your own severe weather plans and make sure you’re equipped to handle this storm.

It’s going to be crucial to watch the track of Irene over the next days. If there continue to be subtle shifts to the east, then the effects we’ll see in the Richmond area will lessen. Landfall in North Carolina is far from guaranteed right now, but it’s coming into focus as a likely scenario. I’ll continue to post updates throughout the week.

August 23, 2011 4:01 PM 0