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Hurricane Irene: Wind, Rainfall, Timeline Forecast For Southern New England

By Terry Eliasen, Meteorologist, WBZ-TV Exec. Weather Producer
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Hurricane Irene at midday Friday (Satellite image courtesy: NASA)

Hurricane Irene at midday Friday (Satellite image courtesy: NASA)

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BOSTON (CBS) – We are becoming more and more confident that New England may be in for its first hurricane in 20 years, since Bob in 1991.

As of late Friday morning Irene was a very strong Category 2 hurricane, bordering on a major Category 3 hurricane.

Hurricane Irene: Check Latest Satellite Images | Tracking Map

Irene is moving nearly straight north up the East Coast and not likely to make any significant landfall until it reaches Long Island and the South Coast of New England.

Check: Interactive Radar | Current Conditions | Weather Map Center

This is significant because the more interaction with land a hurricane encounters generally the weaker it becomes.

Hurricanes generate the majority of the power from the warm ocean and Irene is no different, riding right up the warm Gulf Stream current.

Some weakening is likely with Irene when it reaches the Mid-Atlantic ocean waters due to cooler ocean water temperatures in the 70’s.

Typically hurricanes need water 80 degrees or higher to sustain their strength.

Weather models are converging on a solution somewhere between a Hurricane Bob and Hurricane Gloria track.

This would bring the eye of Irene anywhere from Springfield, Massachusetts to Interstate 495. This would be much different than recent close calls from storms like Earl and Ophelia.

These recent storms took a track to the east of Cape Cod and spared most of us from the damaging hurricane force winds.

The strongest winds are always on the east side of the storm, so given the current track a good portion of central and eastern Massachusetts would be in line for very strong winds.

Here is the breakdown as we currently see it:

TIMELINE

The first rain bands from Irene will come ashore the South Coast Saturday morning and slowly pivot northward during the afternoon into the Boston area and beyond.

These will be tropical rains capable of dropping an inch or more of rain in a few hours.

The rain will increase in coverage and intensity during Sunday morning and midday as the hurricane draws closer.

Winds will be gusty out of the southeast as early as dawn Sunday morning, especially along the South Coast.

The winds will gradually increase through the morning hours of Sunday and by midday and afternoon all of southern New England will be in the envelope of Hurricane or Tropical Storm force winds.

The wind and rain will be heaviest during the hours of 5 a.m. to 5 p.m., there will likely be a quick shutoff to the rain after that timeframe.

The winds will shift to the northeast and become lighter overnight.

Monday will be sunny and pleasant.

STORM SURGE AND COASTAL FLOODING

This is without a doubt the biggest concern with Hurricane Irene.

The combination of astronomically high tides (due to a new moon) and a storm track to the west (bringing powerful SE-SW winds) will create a very dangerous situation all along the South Coast and particularly in Narragansett Bay and Buzzards Bay.

The Bays can act like a funnel and large amounts of water can be chanelled in with no place to go but over land.

With a perfect track, storm surge in the Bays could reach as high as 5-to-10 feet leaving numerous oceanside locations under water.

High tides along the South Coast occur around 8 a.m. and 8 p.m. on Sunday but tides will likely never truly appear to go out.

Seas will swell as high as 30 feet just offshore.

WINDS

As we have been saying, the strongest winds are always on the east side of a hurricane, in particular the northeast quadrant of the storm.

Picture a hurricane as a symmetrical circle sliced into 4 quadrants.

The top right section (northeast) is where the most damaging winds will occur.

With the current forecast track, a good deal of central and eastern New England will be right in that quadrant. Therefore residents along the South Coast, Cape Cod and the Islands can expect hurricane force winds (74 mph+).

Winds will decrease as you get farther inland by about 5-to-10 miles due to the friction of the land interacting with the winds.

So all of inland Massachusetts will likely see tropical storm force winds (39-to-73 mph).

This is still plenty strong enough to cause widespread tree damage and numerous power outages, especially given that we will be in this envelope of wind for 6 hours or more Sunday afternoon and early evening.

Watch Melissa Mack’s forecast:

RAINFALL

Again, the heaviest rainfall is always to the west of the track, meaning in this scenario the rain bulls eye will be in western Massachusetts and western New England.

There could be as much as 5-to-10 inches-plus in those locations.

We are forecasting 2-to-5 inches through central Massachusetts and lower amounts in far eastern areas.

The National Weather Service has issued a Flood Watch for the entire area due to the possibility of significant urban and poor drainage flooding.

We wouldn’t likely see much large river flooding because as of now we could stand as much as 5 inches in a 24-hour period before there would be large stem river concerns.

The smaller streams would, however, be at risk.

Please stay tuned to updated forecasts and if you haven’t done so already, begin to make preparations.

This is a very serious weather situation, perhaps the strongest hurricane we have seen in decades.

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