DAYS 1-5 (SEPTEMBER 25-29)<\/p>\n\n\n\n
Blocking dominates for 5 days and during this time we’re going to be impacted by a storm system. Does that mean 5 days of full on stormy weather with wind and rain? Most certainly not, and this is a great opportunity to break down the different aspects of a complex system and all parts of it, and talk about it in a way you won’t generally hear on TV, radio, or many other web locations.<\/p>\n\n\n\n
Overview… Large scale blocking has placed a sprawling high pressure area in southeastern Canada, north of New England, and this is expected to remain generally in place with a slight nudge to the southwest. Meanwhile, low pressure is developing off the Mid Atlantic Coast, and the upper low pressure area helping to kick it off will be quasi-stationary through the next few days. This is your blocking set-up.<\/p>\n\n\n\n
Storm Evolution… While the high remains generally in place to our north and eventually northwest, the low pressure area organizes and drifts to the north in the waters well off the Mid Atlantic Coast. It then starts to get trapped by the upper low, bending to the left in its track. Typically, as these surface lows make this turn, and begin the process of becoming vertically stacked (directly underneath the associated upper low) they are peaking in intensity. This one will do just that, and the pressure gradient between it and the high to the north helps to create in area of enhanced wind. Once the stacking is completed, the low has matured and will start to weaken. The surface low in this particular case is now expected to be pretty far south of New England when it turns westward and peaks out, moving close to or even onshore in the NJ \/ Delmarva region, before looping back out in its weakening phase, eventually moving east northeastward and passing just south of or even over far southeastern New England. The northward movement would take place today (Friday), the turn to the west Saturday, the loop on Sunday, and then east northeast movement and gradual exit Monday and Tuesday.<\/p>\n\n\n\n
Storm Impact \/ Timeline… The evolution of this pattern, which actually started a couple days ago, has already set-up a northeasterly air flow, which will continue and also be strengthened by the storm’s evolution and interaction with high pressure to the north. This builds seas and I expect a lot of rough surf along the coast and the threat of splash-over and minor to potentially moderate coastal flooding around high tide times, with greatest threats being the midday Saturday and midday Sunday high tides. East-facing and north-facing shores are most vulnerable. With the full moon Saturday the tides are already astronomically high, so this will add to the potential for flooding. In terms of clouds and rainfall, there’s quite a bit of dry air in place in the region to start out, so today I just expect an increase in high to mid level cloudiness with some limited sunshine (most north and west, least south and east), with also some areas of lower cloudiness coming in off the ocean. I’ve slowed the timing of the rain’s onset down a little bit in response to the further south position of the low center. The first area of rain should enter the Cape Cod \/ Islands region this evening, but may be largely dissipated by the dry air in place as it tries to push to the north and west. For this reason, I’m extending the “mostly dry” conditions with just a lot of cloud cover well into Saturday with only limited rain chances. It’s conceivable that a lot of the region will see no rainfall at all through the daylight hours of Saturday, with even some additional sunny breaks possible during that day. It is when the low center goes through its loop phase and starts its turn back to the east northeast that the rain area can advance more significantly and the dry air will be overcome in our region, so that our rain chances go up Saturday night through Sunday and into Monday as well. However, during the daytime on Sunday, the low center will still be far enough to the west for additional dry slotting to take place in our region. This would result in some areas seeing bands of heavier showers while other areas are relatively rain-free for stretches of time, even potentially seeing additional breaks of sun. As the low center makes its closest pass in weakening phase Monday, that is when some of the steadier albeit lighter rainfall can occur in the WHW forecast area. Finally, we’d see this all exit by early Tuesday with improving weather during that day. But let’s not forget the wind impact. A northeasterly air flow will be prominent and increasing as we move through today and Saturday, peaking Saturday night and Sunday as we have the strongest pressure gradient over our region at that time. This is when the strongest gusts of wind can occur. You’ll see in the break-down in the detailed forecast below that I still expect this to be along the shoreline and particularly over southeastern areas (southeastern MA, Cape Cod, Islands). At the low’s furthest reach westward, the wind flow can be more easterly as opposed to northeasterly, but would then back around to north as it subsides later in the event. I haven’t mentioned rainfall amounts yet. This is a little tricky because it’s not like forecasting a uniform coverage with a fairly straightforward gradient. The delayed onset and during-storm variability will make totals somewhat uneven, but in general a 1-2 inch northwest to 2-4 inch event southeast seems most likely. Keep in mind this takes place over a few days and so flooding from rainfall will be quite a minimal threat unless your area happens to get under a band of training heavier convective rainfall for a time. That will be the exception rather than the rule.<\/p>\n\n\n\n
TODAY: Increasing clouds but some filtered sunshine especially west and north of Boston. Afternoon light rain potential mainly Islands \/ Cape Cod. Highs 60-67. Wind NE 10-20 MPH with gusts to 30 MPH inland, 20-30 MPH with gusts to 40 MPH coast.<\/p>\n\n\n\n
TONIGHT: Cloudy. Periodic rain Islands \/ Cape Cod. Chance of light rain RI to MA South Shore. Lows 47-54. Wind NE 15-25 MPH with gusts to 35 MPH inland, 25-35 MPH with gusts to 45 MPH coast.<\/p>\n\n\n\n
SATURDAY: Mainly cloudy but a period of partial sun possible some areas. Rain chances increase from southeast to northwest across the region. Highs 59-66. Wind NE 15-30 MPH with gusts 35-45 MPH inland, 25-40 MPH with gusts 45-55 MPH coast.<\/p>\n\n\n\n
SATURDAY NIGHT \/ SUNDAY: Overcast but a few breaks in the clouds can occur in some locations. Showery rain, heavy at times. Slight chance of thunderstorms. Temperatures generally 56-63. Wind NE (may shift more E at times), 15-30 MPH inland with gusts around 40 MPH, 25-40 MPH coast with gusts 45-55 MPH and isolated gusts as high as 60 MPH (Blue Hill and exposed coastal areas), starting to diminish later Sunday.<\/p>\n\n\n\n
SUNDAY NIGHT \/ MONDAY: Cloudy. Periodic rain. Lows 53-60. Highs 60-67. Wind variable 10-20 MPH, higher gusts, with potential for higher sustained and gusts (depending on low track).<\/p>\n\n\n\n
MONDAY NIGHT \/ TUESDAY: Mostly cloudy. Showers end west to east by Tuesday morning. Lows 53-60. Highs 62-69. Wind variable becoming W 5-15 MPH with higher gusts.<\/p>\n\n\n\n
DAYS 6-10 (SEPTEMBER 30 \u2013 OCTOBER 4)<\/p>\n\n\n\n
Fair, milder to warmer September 30 & October 1. A shower chance night of October 1 to early morning of October 2 followed by fair, breezy, cooler weather then more tranquil and seasonable by October 3. Rain chance October 4 as low pressure arrives from the west in a zonal flow weather pattern.<\/p>\n\n\n\n
DAYS 11-15 (OCTOBER 5-9)<\/p>\n\n\n\n
Zonal flow pattern. A couple systems can bring shower threats but overall pattern is dry, seasonable to mild.<\/p>\n","protected":false},"excerpt":{"rendered":"
DAYS 1-5 (SEPTEMBER 25-29) Blocking dominates for 5 days and during this time we’re going to be impacted by a storm system. Does that mean 5 days of full on stormy weather with wind and rain? Most certainly not, and this is a great opportunity to break down the different aspects of a complex system … Continue reading Friday September 25 2026 Forecast (6:32AM)<\/span>