The storm pushed into the region early this morning from the southwest and holds an inside track, meaning the core of the system should stay just west of New England as it slings up to the northeast throughout the day. This will keep the cold side of the storm mostly in eastern New York and make the precipitation mostly all rain across the six New England states during the most intense stretches of this system.
With the first round of heavy rain having already arrived with the leading warm front, the second round is expected as a more intense cold front unloads more rain tonight.
6 a.m. – Noon
Rain begins to ramp up across Southern New England as some heavier storm cells push through the region. Lighter rain is expected up north. The intensity of the rainfall will fluctuate during this stretch with some mini-breaks in between. This is essentially when the warm front passes through the region, setting up a surge of moisture and warmth for the rest of the day.
Noon – 6 p.m.
Ongoing rain will continue throughout New England with a likely drop in intensity across Boston and Southern New England for an hour or two in between the frontal passes. There could be a short stretch where Boston stays dry, but it’s tough to know exactly when with so much moisture in the atmosphere. I would plan for mostly rain during this time, so keep that umbrella handy as you head out to lunch and back home. You’ll notice the wind picking up, with wind gusts near 20 miles per hour.
6 p.m – Midnight
The next surge of rain arrives. The strong cold front will push into the region from the west and bring a wide swath of heavy downpours onto the scene with the chance for some embedded thunderstorms. Winds will really ramp up with two sharply contrasting air masses interacting. This second wave can lead to pretty intense rainfall — as much as 1 inch of rain an hour at times — especially between 6 p.m. and 10 p.m.
Closer to midnight the front exits off the coast and things calm down quickly, with some parts of Northern New England seeing a switch to light snow on the cold side of the system.
A soaking rain will unleash anywhere from 1½ to 3 inches expected in a nearly 24-hour window. Some locally higher amounts to 4 inches could be possible should recurring heavy storm cells track over the same area. Widespread rainfall rates will range from steady to heavy at times throughout the day with some breaks mixed in.
The strong southerly flow over New England will keep the moisture supply from the Atlantic intact throughout the entire duration of the storm.
Considering the warm air blanketing the region, rapid snowmelt is also a factor to consider in terms of the flooding potential. Combining new rainwater with existing snowmelt may lead to some localized flash flooding in spots, especially across portions of interior New England in Vermont, New Hampshire and the Berkshires. Melting snow will add another inch or so of water.
Most river levels are low from the ongoing drought and will help minimize some of the excessive rain and runoff, but if we end up seeing some of the higher rainfall amounts in overloaded areas that could lead to flash flooding.
About a dozen or so waterways across New England are forecast to reach minor flood stage Wednesday and Thursday. This has led to flood watches issued in portions of Western and Northern New England. But generally flooding should be minor.
You’ll hear many meteorologists reference the “low-level jet” (the jet stream) and this simply refers to the ribbon of fast-moving wind that is directing the storm into the region. With it being closer to the surface, we’ll feel some of that power as the deep bend in the jet stream leads to a bottleneck effect — loads of fast-moving air above our heads traffic-jamming together and thus ballooning closer to the surface.
Strong winds will also be a factor in this storm as the day progresses, with some gusts ranging from 30 to 60 miles per hour. They’ll most likely peak between 3 p.m. and 8 p.m. with the strongest gusts near the coast, so you’ll want to make sure to secure items in your yard. This has led to high wind alerts across much of the eastern and central portions of New England for today.
A few areas could even see power outages with tree limbs coming down. I wouldn’t be surprised if there were a few whole trees coming down with the soil becoming so saturated by Wednesday evening.
There could be a brief switch over to snow across parts of Western and Northern New England on the backside of the storm as the storm pulls away and colder air works in behind the system. About an inch to as much as 4 inches could be possible in a few spots.
New England storm breakdown
Boston area: Overnight light showers will turn into periods of steady to heavy rain Wednesday morning. Some breaks in the action can occur Wednesday afternoon with steady rain returning in the evening as the cold front nears. Boston could see around 2 inches of rain when it’s all wrapped up by midnight. Strong winds will be in place Wednesday afternoon with some gusts from 30 to 60 mph.
Central/Western Mass.: Widespread rain will ramp up early Wednesday morning and stay consistently rainy during the day with some heavier pockets than others. Rain totals should range from 2 to 3 inches, with locally higher amounts to 4 inches. The heaviest of rain will be Wednesday afternoon and evening.
Cape and Islands: Light to steady rain early Wednesday morning with the best chance in the region to see a prolonged break in the weather during the early afternoon. A second round of rain will ramp up Wednesday late afternoon or evening with heavy rain expected. About 1 to 2 inches of rain expected, but whipping winds will ramp up in the afternoon and evening with some gusts of 30 to 50 mph.
Rhode Island: Steady rain expected early Wednesday morning with some pockets of heavier downpours. Showers become more broken up and spotty early afternoon ahead of a second wave that will bring heavier rain and the chance for thunderstorms. A few storms could pack strong wind gusts of 30 to 50 mph across the entire state.
Northern New England: This will be a mostly rain event across Northern New England with light to steady rain Wednesday morning evolving into pockets of more moderate to heavy rain during the evening. New Hampshire could see the highest rain totals of the three northern states, with totals ranging from 2 to 3 inches and locally higher amounts. Melting snow could amplify the flooding across mountainous and hilly areas of Vermont, New Hampshire and western Maine. Some cold air will filter in behind the storm as it pulls away Wednesday evening, leading to a couple of inches of snow possible into early Thursday for higher elevations.
Ken Mahan can be reached at ken.mahan@globe.com. Follow him on Instagram @kenmahantheweatherman.
