Incoming nor’easter may bring less rain than initially predicted

April 25, 2017

2 minutes to read

In winter, when there’s a storm moving up the coast, meteorologists often tweak the snowfall numbers as it gets underway. There’s a big impact when a 4-to-8-inch storm turns into a 1-to-3-inch storm or an 8-to-16-inch storm.

With a wet nor’easter, the trend of rainfall up or down is less impactful — unless it’s over 3 inches of rain — but it’s still important.

While the Greater Boston region is going to experience wet weather into Wednesday, the storm now looks like it’s a shorter-duration event bringing less rainfall than initially forecast. The storm is going to weaken as it moves north, diminishing the intensity of the rain. We definitely won’t see the deluges people experienced in part of North Carolina from this same storm.

Rainfall through Wednesday won’t create any freshwater flooding issues. (Dave Epstein)

In the loop below, notice the “L” — the low pressure storm center — literally weakening and vanishing as it moves toward New England later Tuesday and Wednesday. This is the reason for less, not more, rain than earlier predictions.

As the storm moves up the coastline it will weaken and finally die out over eastern Maine Wednesday night (Tropical Tidbits)

The image below is not a forecast model; it’s the radar from Tuesday morning. Notice the very heavy rain (reds and oranges) over the Carolinas compared with locally lighter rain (blue and greens). There’s also a big gap between the two, one of the reasons I’m forecasting we won’t see steady, all-day rain on Tuesday. That very heavy rainfall will never make it this far north.

Rain continues heaviest over the Southeastern United States with less intense showers in southern New England. (NOAA)

You can expect showers for much of Tuesday but also breaks in the precipitation lasting an hour or more. It won’t be until the evening commute when the heaviest, steadiest rain arrives. Even then, not everyone will see the same intensity.

Winds will be coming in from the east all day. This cool ocean air will prevent most areas from exceeding 50 degrees. There is the chance for some minor coastal flooding at the time of high tide, mostly as a result of the king tides this week combining with the storm.

With this storm moving slowly toward us and another weak system behind it, clouds and the chance of showers are in the forecast for the rest of the workweek. Your smartphone weather app probably shows rain for the next four days, but that’s an overstatement. After Wednesday morning’s commute, there’s just the chance of showers for later Wednesday.

Thursday is a dry day, but a lot of clouds will fill the sky. On Friday, our sun-free period will continue with a few showers. Warmer air will arrive by Saturday, along with a blend of clouds and sunshine. Temperatures should reach the 70s and the lower 80s in some of the warmer spots away from the South Coast.

You can follow Dave Epstein on Twitter @growingwisdom.