Hurricane Melissa’s remnants to turn a rainy weather-maker into a drenching storm for parts of Mass. on Halloween Eve
The good news is that the majority of the rain will be over by or just after sunrise on Friday, which is Halloween.
Over the next few days, we’re going to see countless images coming out of Jamaica and Cuba showing the sheer devastation that Hurricane Melissa has wrought. Trillions of gallons of water will then be moved northward within this weather system as the hurricane continues to lose strength on its approach to Bermuda before eventually moving into the North Atlantic.
While all of this is going on in the atmosphere, low pressure will be moving from the Tennessee River Valley into Pennsylvania, New York, and eventually northward through Maine and into the Canadian Maritimes. This storm is what’s bringing a burst of heavy rain on Halloween Eve — late Thursday afternoon into Thursday night to our area.
By the time we get back to standard time on Sunday, this weather system will have merged with the outer bands of Melissa’s remnants and may actually bring rain to the British Isles early next week.
But the evolution of that merger is key to our forecast.
The atmosphere is a dynamic swirl of energy being transported across the planet in a never-ending attempt to achieve balance. In addition to pockets of energy, areas of moisture, including the rain we’re going to see on Thursday, move from point A to point B. One of the fascinating things about weather systems is that they can interact with one another sometimes in meaningful ways and other times just enough for one of them to enhance the other.
Check out the moisture transport loop below. To help you understand what you’re seeing, think of a column of air from the ground up. That column contains moisture. Within this, there are an infinite number of little columns within a weather system. Low pressure, which is going to bring our rain and wind for Thursday, has its columns and those pockets of moisture that are being transported. Melissa has its own column of moisture, and that too is being transported.
If you look at the loop closely, you’ll notice the moisture around Melissa, that’s the red blob out in the Atlantic getting pulled northwestward toward our weather system moving into New York on Thursday. These two moisture transports are then going to begin to merge in some capacity over us before no longer being discernibly separate a couple of thousand miles away.
How this all impacts New England
While this is meteorologically interesting, you might be thinking, “OK Dave, but what about our weather?” On Thursday afternoon and evening, we will start to see showers move up from the south. Thursday night, there will be a period of strong winds and heavy rain. The area with the heaviest rain is likely to be over Southeastern Massachusetts, including Cape Cod and the Islands, closest to the moisture feed from Melissa. Here we could see 1 to 3 inches of rain, but it would not surprise me if we saw a few spots, most likely Cape Cod, with up to 4 inches.
Because the system is moving so fast, any flooding would be temporary in nature and mostly inundate some streets. This will all be occurring mostly while we are sleeping as well.
The good news is that the majority of the rain will be over by or just after sunrise on Friday, which is Halloween. Drier air gets swept into the system, and that dry slot moves over us just in time for trick-or-treaters to head out, keeping the weather not only rain-free but relatively mild.
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