Oct 27, 2016 7:08 PM
NH1 First Alert Weather: Heavy Rain Overnight, AM Commute Delays & Flooding
NH1 Chief Meteorologist
A potent short wave trough is approaching the region tonight allow for rapid deepening of a surface low over southern New England tonight which will move into the Gulf of Maine on Friday. As a result, snow, wind, and rain will be factors of the forecast. Precipitation will continue to gradually spread northeastward this evening, with a good chunk of the precipitation type being rain.
Winds will be another issue as well. Strong onshore winds should begin to affect the coast...most likely the immediate coast..Overnight and Friday morning. Expected wind gusts will range from 20-40 mph. The rain and wind will subside from S to N during the day on Friday, with only linger showers expected for southern zones during the afternoon hours. Rain and snow should continue in the mountains, but probably be more rain than snow as the day progresses outside of the highest elevations.
However, at elevations mainly above 1000 feet in W/SW NH some light snow accumulations are possible with no accumulation expected (generally less than 1 inch). The column should be cold enough for snow at higher elevations across northern NH and the western ME mountains, with snow amounts highly dependent on elevation. It`s possible that from late tonight through Friday that elevations above 2500-3000 FT will see greater than 6 inches of snow. Below that level, amounts will be lighter.
As pressure falls rapidly occur over southern New England tonight (mainly after midnight), additional lift in the atmosphere will increase the intensity of the rainfall overnight. The heaviest rainfall will happen after midnight through the early morning of Friday. Due to the deepening low and moist inflow off the water, this should allow for heavy rainfall with potential of 1 to 1.5 inches expected through midday Friday. Some localized poor drainage flooding is likely during the morning commute, especially where leaves clog storm drains.
This is welcome news for the Extreme Drought still happening across Southern New Hampshire where Concord, NH is still running close to 8" of rain below the average since January 1st...even after a somewhat wet October which produced about 3.5" of rain so far with more coming tonight!