Flood Watches up for NH

Finally after two weeks of dry weather and warmth, NH and ME are going to pay. A major storm is on our heels, and models are pumping out 3-5 inches of rain, which, Gray (forecasting office) thinks could be too little. The storm will become negatively tilted over NH and stall. Will 2-7 feet of snow in the White Mountains still, this much rain may be bad..The most prone areas will be the Merrimack Valley and Pemigewasset Valley, directly downstream from them. Be careful on stream crossings if you hike this week, they are likely to be much worse then they already are. -Matt

Matt's right about the stream crossings. The Saco was down a little in Conway this morning, but it has been pretty high recently considering the fact that we haven't had any rain in a while. Be careful if you do any hiking in the mountains this week.

Pemi looks pretty high......
http://waterdata.usgs.gov/nh/nwis/u...format=gif_default&period=31&site_no=01074520

Hmmm... and the low pressure area's becoming "negatively tilted" which means a nice conveyor belt of moisture from the Gulf by way of the Atlantic, and no quick end to the heavy rain. Should be better by the weekend, but I'd skip Owl's Head tomorrow. Big mess. Get out the basement pumps.

Weatherman

Interesting that the EB hydrograph peaked late Monday night at about 7000 cfs and has now (3 pm Tuesday) dropped to about 4000 cfs, although could be leveling off and on the rise again soon?

I thought the same thing.......

Now back up to 5000. I'm no hydrologist but it seems to me that the Pemi must be one of those rivers that responds very quickly to rain that falls, and rain that stops. There was a break in the rain for a while late last night/early this AM.

Looks like 3-6 hours more should about do it.

Weatherman

weatherman said:

Now back up to 5000. I'm no hydrologist but it seems to me that the Pemi must be one of those rivers that responds very quickly to rain that falls, and rain that stops. There was a break in the rain for a while late last night/early this AM.

Looks like 3-6 hours more should about do it.

Weatherman

Click to expand...

I do not have a ppt gauge for the East Branch, but if the rain picked up again the past few hours, the increase to 5000 cfs certainly makes sense. However, I was surprised by rapid drop late last night through mid-day, as I thought that the ppt would melt even more of the snowpack, making the hydrograph less "flashy" (peaked).

My name is Sabrina and I am addicted to viewing the Pemi USGS Hydrograph...

So long as it keeps dropping for the weekend.......

weatherman said:

Now back up to 5000. I'm no hydrologist but it seems to me that the Pemi must be one of those rivers that responds very quickly to rain that falls, and rain that stops. There was a break in the rain for a while late last night/early this AM.

Looks like 3-6 hours more should about do it.

Weatherman

Click to expand...

Many different conditions affect the amount that runs off. Whether the ground is still frozen under the snow so it doesn't soak in, or if it is after thaw is it now already to saturated to take in more. When I worked in Pepperell we used to follow the hydrograph info when operating the old hydro plant. About 435 sq.mi. of drainage and you could peak in 3-4 hours or 2 days depending on conditions. With the heat we had last week and early in the weekend the ground probably took quite a bit and now the burden is going into the waterways.