October 28, 2012 at 1200 Noon High Wind Watches are now in effect for all of New Hampshire. A Coastal Flood Watch is also in effect for Coastal Rockingham County beginning Monday morning through late Monday Evening.
A Weather Advisory is issued if after review of pertinent weather information it is determined that escalating emergency conditions may be possible.
Scattered light rain showers will be possible later this afternoon and will remain possible through tonight. Non hazard winds are expected through daybreak Monday with any wind gust expected to be 28 mph or less. It will be 9am Monday before winds reach hazard levels across the New Hampshire Seacoast, as well as across Connecticut and western Massachusetts. Winds will reach hazard levels across the rest of New Hampshire after noontime on Monday.
The forecast for Monday and beyond continues to remain difficult. However, model guidance is exhibiting better agreement. Hurricane Sandy will interact with a cold front to create a major impact coastal cyclone beginning Monday morning and lasting through at least Tuesday. The latest model guidance has changed little as far as the track and timing of the storm moving inland into southern New Jersey or even a bit further south. The storm’s wind field will be very large, so the track won’t make a huge difference.
Impacts are broken down below by type:
Rainfall: Rainfall amounts of 1-3 inches will be widespread across the New England region. Rainfall amounts of 1-2 inches will be possible across northern New Hampshire, from the Lakes Region northward. Localized higher rainfall totals of 3-5 inches can't be ruled out. The heaviest rain should begin by 3-4 pm Monday across New Hampshire. The heavy rain period should end by 2-4am Tuesday for most and 10am Tuesday across northern New Hampshire. Heavier rain will taper to scattered showers that will be lighter in intensity for the remainder of the day Tuesday.
Wind: Widespread damaging winds will be possible over an extended period of time. In New Hampshire, the strongest winds should be during the period from 2pm Monday through 2am Tuesday morning. The New Hampshire Seacoast should see sustained winds of 30-45 mph, with gusts of 50-60 mph. Interior sections of New Hampshire should see sustained winds of 20-35 mph, with gusts of 35-55 mph, strongest across interior southern New Hampshire and through the higher terrain. The winds should gradually diminish later at night and throughout the day on Tuesday. Peak gusts should be 30-40 mph by Tuesday afternoon. We should see gusts of 25-35 mph on Tuesday night.
Thunder and Lightning: Low amounts of lightning will be possible during the period of heavy rainfall. In addition, isolated tornadoes cannot be ruled out from the beginning of the heavy rain period through 10pm Monday. The chances of this will be 5%.
Storm surge: Onshore winds will bring an enhanced risk of coastal flooding across the Seacoast of New Hampshire at times of high tide. Storm surge should be 2-5 feet for the New Hampshire Seacoast. This should occur Monday and Monday night for the New Hampshire Seacoast. The worst of the coastal flooding should be at times of high tide. This should be Monday evening and into Monday night.