First Alert: Tracking what could be the rainiest day of 2024

It’s been a while since we’ve had substantial rain. This could top the charts in just about every which way.

An approaching weather system will have an abnormal amount of water vapor transporting into the region and lead to a wet Wednesday. The scale of this event will be confined to the eastern seaboard, and will intensify over New England as it progresses through Wednesday.

See live radar for Boston, Mass.:

We’ll feel this storm in multiple parts: the warmth, the water and the wind.

The Warmth

Because it is winter, I figured I’d start with the warmer air.

This storm has origins across the Northern Gulf of Mexico, thus the air advected with it tends to be warmer. Temperatures late Tuesday night will sit into the upper 30s, and early Wednesday we should cross the threshold into the 40s and 50s, especially across Cape Cod. High temperatures Wednesday afternoon touch 60 degrees, which will rival records for some.

• Westfield, Massachusetts – Forecast: 61 degrees, Record: 61 degrees
• Bridgeport, Connecticut – Forecast 63 degrees, Record: 65 degrees
• Worcester, Massachusetts – Forecast 62 degrees, Record: 62 degrees

The Water

It will be hard to enjoy the warmth, given the onslaught of rain, though. The forecast turns wet early Wednesday morning, with clouds and scattered rain before daybreak.

By mid-morning, widespread downpours are across eastern Massachusetts and Cape Cod. Isolated rumbles of thunder accompany this. At 1 p.m., a strong line with squalls will migrate from western Massachusetts, through Worcester County and cross the Boston Metro shortly thereafter. Again, given how strong winds are aloft, we think this moves through at a decent pace.

While a few downpours are possible, we await the heaviest rain Wednesday evening. Around 6 p.m., one final surge of rain is likely, with rainfall rates near 1 inch per hour. Because of the hours of rain preceding, street flooding becomes more likely at this point. The threat is region-wide, and will need to be monitored across central Vermont and New Hampshire, where rapid snowmelt is likely to occur. This is triggered by a combination of heavy rain, warmer temperatures and previous snows.

This is where we see the largest discrepancy. Higher resolution guidance is now hinting at a break in showers around 3 p.m. and 5 p.m., and that could cut down totals somewhat, though this could still end as a very wet day.

Forecast rain amounts are between 2 and 3 inches around the Massachusetts Turnpike, and between 1-3 inches across the Cape and Islands and through the Connecticut River Valley. Even if we receive the lower end of the forecast, this could still cross the threshold into a Top 5 wet calendar day.

It should also be noted that the soggy conditions will weaken root systems – heavier winds could attribute to snapping trees, and isolated power outages.

The Wind

Winds are starting out strong – near 20 mph in Boston and gusts near 30 mid-morning. They’ll gradually weaken around 11 a.m. in the metro, but still remain across the south coast near 40 mph.

In the early afternoon, we’ll see another push of winds at 30 mph throughout the interior, and coastal gusts near 45 mph through Cape Cod. Winds are expected to intensify by the evening (between 4 p.m. and 7 p.m.) near 50 mph in Boston and 60 mph for New Bedford and Cape Cod. At this time, power outages will need to be monitored.

The rain will quickly collapse behind the strong winds and Thursday morning should start dry. There will be breezy conditions Thursday, and this will hurt.

Temperatures are swinging from the 60s on Wednesday, and crashing into the 40s, then 30s by the end of Thursday, marking winter’s return.

Wednesday's Hourly Rainfall Rates