Irene is here, flood, gales to follow

Irene is behaving just as predicted, and drenching rain is spreading northward through Vermont. Already, early this morning Springfield got an inch of rain in two hours.

http://blogs.burlingtonfreepress.com/weather/2011/08/28/irene-is-here-flood-gales-to-follow/

Irene is here, flood, gales to follow
7:19 AM Sun., August 28, 2011 | Permalink
By Matt Sutkoski

Irene is behaving just as predicted, and drenching rain is spreading northward throug Vermont.

I’ve noticed it goes from just a sprinkle to a heavy rain very quickly. Already, early this morning Springfield got an inch of rain in two hours.

Flooding looks to be the major issue with Irene in Vermont. The National Weather Service in South Burlington says anybody who gets over four inches of rain is subject to major flooding.

Most of the state will see over four inches of rain.

The rain will continue to intensify all morning, and continue at a torrential pace all afternoon. I imagine the flooding problems will start at mid afternoon at the latest, and the flash flooding of small brooks and streams will become really bad late this afternoon and through this evening.

The flooding on the bigger rivers like the Winooski, Lamoille and Missisquoi will start later tonight and continue into tomorrow.

At this point, forecasters say the Champlain Valley will get the worst of the rain. The thing something called a deformation zone will set up there. Basically, the zone is an area where the wind flow shifts and the air rises a little more efficiently. That enhances the ability of the atmosphere to wring out more water as rain.

Which means the rain would be that much heavier in the deformation zone. Best guess is the Champlain Valley and the Vermont/New York border further south could get five to seven inches of rain from Irene, with the rest of the state getting four to six inches.

The wind hasn’t really become a factor yet in Vermont, and it won’t be too bad until this afternoon. By late afternoon, they’re still predicted sustained winds of 30 to 40 mph with gusts to 60.

As of 7:15 a.m., Central Vermont Public Service reported about 600 customers without power, and Green Mountain Power had 60 homes and businesses with no juice. All these were in southern Vermont.

You’ll see the number of people without power increase astronomically today and tonight.

Somebody asked me what’s the difference between sustained wind and gusts. Sustained wind is the speed of the wind over a two minute period. Gusts, of course are much stronger. A gust is the maximum measured wind speed. A gust can last just a few seconds.

So the bottom line is that today, for awhile, the wind will constantly blow at least 30 mph, but there might be intervals of a few seconds where the gale increases to 60 mph.

One thing I’ve noticed with Irene as it moves up the coast is the strongest winds come when the storm is just east and northeast of a given location. New York’s LaGuardia airport reported a wind gust of 64 mph just a little while ago.

So I’m guessing the highest winds will come late this afternoon and early this evening.

As I said yesterday, keep checking the Burlington Free Press Web site for continuing updates on Irene..