DAYS 1-5 (SEPTEMBER 25-29)
If you have outdoor plans today, you can likely pull them off with no more than the potential for a minor interruption from a passing shower if you are in southeastern MA, and without any interruption anywhere else. Some of our guidance has advertised a more gloom & doom scenario making it look like at least a partial wash-out for today with that wave of low pressure. These forecasts will not be accurate and even some of those models have now backed off and are showing a more reasonable solution. How this thing evolves is that the front crawled into the region yesterday, sitting right over our eastern coastal waters now, will be the focus for some redevelopment of showers with the diurnal heating that takes place today. These will be scattered and relatively small, moving northward along the frontal boundary. But as a low pressure circulation to the south gets organized and starts its northward movement, the first thing we will see is that frontal boundary come back to the west, but it’s not going to do so all that quickly. I think any shower activity that occurs will be confined to Cape Cod and parts of southeastern MA through dusk with any other shower activity offshore, and a more widespread area of showers developing west of the low pressure wave, but still to the south of New England. The main impact from this is likely to be during the overnight hours to the sunrise hour of Sunday, with most widespread rainfall in RI and eastern MA, perhaps southeastern NH eventually. But while that frontal boundary has never really been in a hurry to move, the wave of low pressure moving up along it will be cruising at a good clip, and once beyond our latitude it will finally swing that frontal boundary eastward and outta here, and after the iffy start Sunday morning, the rest of the day will feature great weather with incoming dry air – something many of you have been waiting for after several days of higher humidity! It is at this point that we will see a westerly flow take over the weather pattern with some nice dry air in the region for Monday. However, with a trough of low pressure moving through the Northeast, a wave of low pressure is going to be traveling through it, and will bring a warm front / cold front combination across our area Monday night and Tuesday, with again some opportunities for showers. There will be some timing tweaks needed for the fronts and shower threats as we get closer to it. When we reach Wednesday, with the trough still over us but high pressure over the Great Lakes and the surface front having departed, we will receive a delivery of fresh polar air via Canada and it will be a genuine “feel of fall” kind of day.
TODAY: Early morning valley, swamp, and bog fog dissipating by mid morning. Sunniest eastern CT, central MA, and southwestern to south central NH with variable clouds RI, eastern MA, and southeastern NH into afternoon then a cloudier trend all areas by later in the afternoon. Isolated showers this afternoon mainly MA South Coast to South Shore. Humid, especially eastern areas. Highs 71-78. Wind SW to variable 5-15 MPH.
TONIGHT: Mostly cloudy. Isolated to scattered showers during the evening. Numerous to widespread showers overnight. Areas of fog. Humid. Lows 61-68. Wind variable up to 10 MPH.
SUNDAY: Mostly cloudy early morning with lingering showers eastern MA and southeastern NH. Sun and passing clouds from mid morning on. Drying. Highs 70-77. Wind W 5-15 MPH, higher gusts possible.
SUNDAY NIGHT: Partly cloudy. Lows 52-59. Wind W 5-15 MPH.
MONDAY: Mostly sunny. Highs 67-74. Wind W 5-15 MPH, diminishing.
MONDAY NIGHT: Increasing clouds. Chance of a shower late. Lows 55-62. Wind variable up to 10 MPH.
TUESDAY: Variably cloudy. Chance of showers. Highs 65-72. Wind SW to NW 5-15 MPH, higher gusts.
TUESDAY NIGHT: Clearing. Lows 48-55. Wind NW to N 5-15 MPH and gusty.
WEDNESDAY: Sun and passing clouds. Highs 62-69. Wind N 5-15 MPH.
DAYS 6-10 (SEPTEMBER 30 – OCTOBER 4)
There are a lot of uncertainties at play in this portion of the forecast. I remain cautiously optimistic that high pressure will keep us generally dry with the feel of early fall to start, then a bit of a warm-up to follow that. However, there will be some “weather bullies” hanging around outside the “playground”. We’ll need to keep an eye specifically on the evolution of low pressure to the south of New England. Whether tropical or non-tropical, this system could end up further north than much guidance has, and suddenly our fair weather outlook would not be so fair anymore. We also need to keep an eye on tropical activity further out in the Atlantic, not for direct impact but for interactions, and of course ocean / coastal impacts as well. And even by the end of the period the jet stream says “hey don’t forget about me!” and may try to send a disturbance our way.
DAYS 11-15 (OCTOBER 5-9)
A continuation of the same general idea. There are still some high pressure favorings on the guidance, but enough “things that can go wrong” out there. I lean toward the dry pattern but this could very well change.