Westward Shift in Irene Track

Beginning late last night and continuing today, the models have trended back to the west with Irene's path. This slight shift is due to the presumption that Irene will not get "picked up" by a short wave moving out of Canada which would have pushed her more northeast and towards Boston. She will now likely hug the east coast very closely and bring historic rains and flooding to many of the major cities.


This latest GFS rainfall estimate shows just how much water is going to be dumped along the east coast. Upwards of 8-14 inches in parts of Delaware and New Jersey! New York City should also be concerned with flash flooding and tunnel flooding.

As for Southern New England, while this change in the track has us avoiding a direct hit, we are by no means in the clear. On Saturday, Irene will begin to interact with the cold front that will fire off some severe thunderstorms on our region, which by then will have moved off shore. This interaction will allow her to grow in size, making Irene a very BIG storm in terms of square mileage.

We will actually see some heavy rain in our area starting late Saturday night into Sunday morning. Technically, this rainfall is not part of Irene but you mind as well consider it the beginning of the storms effects.

Since we will be on the eastern side of the storm, expect wind to be the main factor for most of Southern New England. At this point, gusts of 50-95mph seem quite likely to occur on Sunday, with sustained winds probably somewhere from 35-45 mph. Total rainfall from Irene should total around 3-6 inches but I would suspect much of that falls late Saturday night into Sunday morning. Once the eye gets close to eastern Long Island, the vast majority of the rainfall will lie on the western side of the storm.

Storm surge will be a major factor for immediate coastal areas. Tons of water will be pushing northeastward ahead of Irene, likely causing some moderate to major flooding in south facing coastal areas.

So to recap...

- Westward shift in track means less rain for us but raises the possibility of stronger wind gusts and storm surge flooding.
- Storm speed is slowing a bit with lack of mid level driving feature. Landfall expected near NYC sometime Sunday night.
- Heavy rain ahead of the storm begins Saturday night
- Irene will likely be a category 1 or tropical storm by the time she makes landfall, since this new path does not keep her over the water.

This new track is obviously good news for us in Boston but by no means is this guaranteed to occur. You all know that hurricanes are extremely hard to forecast and since this event is still over 72 hours away, there is plenty of time for the track to change. These storms typically turn to the northeast so a path that follows the east coast closely is unusual. Nevertheless, this is how it seems to be playing out right now.

Everyone in the region should be monitoring forecast changes. Usual updates to track changes from the National Hurricane center happen later this evening at 5, 8 and 11.