008 FXUS61 KBOX 070711 AFDBOXArea Forecast Discussion National Weather Service Boston/Norton MA 311 AM EDT Sun Sep 7 2025
.SYNOPSIS... Noticeably cooler with continued shower activity today as yesterday`s cold front lingers off shore. Drying conditions late-afternoon into the overnight, from northwest to southeast. High pressure building in from the west tonight into much of next week, bringing fall-like temperatures to the region. Will watch a coastal low pressure system for the midweek as this may bring showers to the south coast, Cape Cod, and Islands.
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.NEAR TERM /THROUGH TONIGHT/... Key Messages:
* Showers continue throughout today, bringing much needed rain to the area.
* Noticeably cooler, with well below normal high temperatures.
The cold front that brought severe weather to southern New England on Saturday will be slow to exit out to sea today, as an mid-level ridge is located off shore. To our north, the mid-level trough will breakdown and the front will washout. Until then, an anafrontal wave will bring continued rain showers throughout the day with at times moderate rainfall. Rainfall rates are manageable, 0.25-0.50" an hour. But with isolated convection, those rates could be higher. Steady rain like this is needed as much of the region has been well below normal for rainfall. HREF mean QPF lines up fairly well with our thinking for additional rain totals today, which are in the ballpark of a widespread 0.5-1.0", with an outside chance for amounts to top 1.5" within convective showers. Rain will wrap from northwest to southeast late this afternoon, showers may linger longest across Cape Cod and the islands this evening.
Temperatures this afternoon are around 15-20 degrees cooler for the most part. Afternoon temperatures are generally in the 60s with dew points falling through the low 60s into the upper 50s.
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.SHORT TERM /MONDAY THROUGH MONDAY NIGHT/... Key Messages:
* Showers exit overnight with clearing skies from northwest to the southeast. Tonight and Monday night will have the potential for effective radiational cooling, resulting in below normal overnight low temperatures.
* Quiet and feeling like fall for the start of the week.
Few showers linger across Cape Cod and the Islands as the cold front through the first-half of the night, and dry early Monday morning as high pressure builds in from the west. Clearing of the clouds occurs and coupled with light winds, should result in radiational cooling with areas of fog possible. Temperatures fall well into the 40s and lower 50s, it`s possible a few areas fall to the low 40s, mainly across northern Worcester County and northwestern Massachusetts.
Quiet conditions for the start of the work week with an area of high pressure building on Monday. Northwest flow will usher in a cooler and less humid airmass. 850mb temperatures are +5C to +7C and with adequate mixing, high temperatures are expected to be on either side of 70F. With no change in the airmass and synoptic features, Monday night will be quiet and cool. Clear skies and light wind should allow for another night of radiational cooling. Similar to the night before, overnight low temperatures are on either side of 50F with the coldest spots in northern Worcester County and far northwestern Massachusetts. Here lows could dip down to 40F.
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.LONG TERM /TUESDAY THROUGH SATURDAY/... Key Messages:
* Taste of fall with below normal day and nighttime temperatures.
* Mainly a dry week ahead, with a chance for showers from a coastal storm Wednesday, but there remains uncertainty with this part of the forecast.
The upper-level pattern heading into next week features a mid-level ridge building across the central CONUS. Towards the end of the week a mid-level northern stream trough crosses eastern Canada with the shortwave energy displaced to the north. In general, it is a quiet week across southern New England. Will watch for a southern stream shortwave to ride the outer periphery of the mid-level ridge over the Atlantic towards New England on Wednesday, this could give a few showers mainly to the south coast, Cape Cod, and Islands with less of a chance for rain further inland. There remains uncertainty with this part of the forecast as ensembles haven`t resolved the northwest extent of the precipitation, but we aren`t expecting really any impacts outside of whether or not you need the umbrella for school or work. Otherwise, high pressure provides a dry and quiet week. Temperature wise, as we have been advertising, this week will feel like fall with temperatures in the lower 70s and upper 60s and nights on either side of 50F. The one day this coming week that would be warmer would be Thursday, though it would be fairly seasonable in the upper 70s. A moisture starved cold front moves through Thursday night into Friday and refreshes temperatures for Friday, with highs back in the lower 70s.
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.AVIATION /07Z SUNDAY THROUGH THURSDAY/... Forecaster Confidence Levels...
Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.
Through 12z...Moderate confidence.
CIGs becoming MVFR/IFR across southern New England with SHRA and at times reduced visibilities of 3SM to 5SM. Area of stratus and fog has developed across Nantucket Sound, leading to patchy dense fog 1/2sm.
Today...High confidence in trends, but moderate in timing.
MVFR to IFR in stratus, periods of SHRA through the morning hours. Rain begins to taper off with CIGs and visibilities improving to VFR into the late afternoon. NW to NE winds 5-10 knots.
Tonight...High confidence.
VFR. SHRA clears out for much of the region, lingering slightly longer over Cape Cod and the Islands. Winds primarily W to WNW around 5 knots or lower.
Monday and Monday Night...High confidence.
VFR. Light NW wind 5-10 knots, becoming calm for the first-half of the overnight, then shifting to N and NNE late in the night with speeds increasing 8-12 knots across eastern MA and RI.
KBOS Terminal...High confidence in trends, moderate confidence in timing.
Front becomes hung up through this morning with lingering showers and MVFR ceilings.
KBDL Terminal...High confidence in trends, moderate confidence in timing.
Front becomes hung up through this morning with lingering showers and MVFR ceilings.
Outlook /Tuesday through Thursday/...
Tuesday: VFR. Breezy.
Tuesday Night through Wednesday: VFR. Breezy. Slight chance SHRA.
Wednesday Night: VFR. Slight chance SHRA.
Thursday: VFR.
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.MARINE... Forecaster Confidence Levels...
Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.
Today through Monday...High confidence.
Yesterday`s cold front has become quasi-stationary off the coast, an area of low pressure rides up along the front today with more rain. The cold front moves off shore overnight with high pressure building in from the west tonight into Monday. NW to N winds today with gusts less than 20 knots, N to NNE winds on Monday with gusts less than 15 knots, and seas for both days are 2 to 4 feet.
Outlook /Tuesday through Thursday/...
Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Tuesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.
Wednesday: Low risk for Small Craft Advisory winds with gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers.
Wednesday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
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.BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...None.
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$$ Dooley
NWS BOX Office Area Forecast Discussion