972 FXUS61 KBOX 051203 AFDBOXArea Forecast Discussion National Weather Service Boston/Norton MA 803 AM EDT Fri Sep 5 2025
.SYNOPSIS... Warm and humid conditions briefly return to the region Friday and Saturday, ahead of an approaching cold front. A cold front brings the risk of scattered showers and isolated severe thunderstorms Saturday afternoon and evening, mainly across the interior locations of southern New England. Showers linger behind the cold front late Saturday night into part of Sunday as much cooler & less humid air works into the region. Dry and beautiful weather is expected for the first half of next week with cool nights and mild days.
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.NEAR TERM /THROUGH TONIGHT/... Key Messages:
* Rain this morning will give way to dry conditions this afternoon.
Frontal boundary continues to move from west to east across southern New England this morning with periods of moderate rainfall. Cannot rule out a rumble of thunder as well with marginal instability. Rain moves out early this morning with clearing skies. Isolated warm advection showers cannot be ruled out this afternoon for areas north of Route 2 in northern Massachusetts, as the best forcing is across northern New England. Otherwise, it`s a warm and muggy afternoon, a blend of sun and clouds. Temperatures reach the low to middle 80s, the south coast remains less warm with highs in the upper 70s to 80F. Dew points are noticeably higher and range between the low 60s across interior locations with middle to upper 60s for the coastal plain. Additionally, have breezy S to SSW winds 10-15 mph and gusts up to 25 mph.
Dry tonight, increasing low level moisture along the south coast may lead to areas of fog/stratus. Mild and muggy overnight, lows fall to the middle and lower 60s.
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.SHORT TERM /SATURDAY THROUGH SATURDAY NIGHT/... Key Messages:
* Dry to begin, strong to severe storms develop Saturday afternoon across southern New England interior.
* Cold front is slow to exit and leads to continued rain showers overnight through Sunday morning.
Summer heat and humidly stretches into Saturday with highs returning to the low to middle 80s! Plus, dew points are into the upper 60s to perhaps as high as 70F. This helps fuel convective storms during the afternoon as a mid-level trough and cold front approach, leading to isolated severe thunderstorms across interior New England. SPC does highlight the area of greatest risk well with the Day 2 Outlook. If you are planning to spend the day outdoors, remember to be weather aware!
Early sunshine will help to warm things up as mentioned, also help to build instability, with 1,500 J/kg of mean CAPE based off of HREF with values as high as 2,000 units. The wind field is also looking more impressive with effective shear 35-45 knots and the effective SRH 100+ units. SREF shows modest probabilities for severe weather and the low chance for a tornado for areas of interior southern New England. The fly in the ointment will be timing of the best forcing, as the best lift arrives mid to late afternoon. Area of risk is shown well on the Day 2 Outlook from SPC. Storms are likely to fall apart as the move east and towards the I-95 corridor. Bit of better news, feel that the I-95 corridor will remain free of rain for much of the daylight hours. Tonight there was a discussion whether to upgrade from a Marginal Risk to a Slight Risk but held off due to lower confidence. That said, there will be a reevaluation on the day shift, which could lead to an upgrade in category. Primary hazards are straight-line damaging wind gusts as the DCAPE values are 900- 1,000 J/kg, hail, heavy downpours and a lower risk, as we like to say, a non-zero chance for a tornado. With PWATs nearing 1.8" with isolated area of 2.0" localized flash flooding is possible, especially for urban locations and areas with poor drainage. WPC expanded a Marginal ERO into much of southern New England for areas west of I-95. Timing the convection, reviewing the 00z CAMs storms could fire in eastern NY/western MA as early as 12-2pm with activity continuing through the evening hours. Given poor mid-level lapse rates these storms will likely start to fall apart shortly after sunset. The cold front is slow to exit and leads to showers overnight into the start of Sunday.
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.LONG TERM /SUNDAY THROUGH THURSDAY/... Key Messages:
* Feeling cool and raw on Sunday with showers activity through the first-half of the day.
* Fall feel returns for next week along with mostly dry weather.
Areas of rain will continue Sunday morning, with showers lingering the longest on the Cape and Islands. The cold front finally shifts out to sea with clearing skies Sunday night into Monday. Sunday will feel much cooler as the region is on the cold side of the front with temperatures in the lower 70s and upper 60s.
Surface high pressure and rising mid-level heights Monday into the middle part of next week. Dry fall-like conditions are anticipated as highs only reach the lower 70s and upper 60s and overnight lows in the low 50s to upper 40s. Next chance for rain could come late Wednesday night into Thursday with the passage of a weak low pressure system.
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.AVIATION /12Z FRIDAY THROUGH TUESDAY/... Forecaster Confidence Levels...
Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.
12z TAF Update...
Today... High Confidence. Moderate on timing of improvements to VFR.
IFR cigs scatter out this morning beomcing VFR for the afternoon. Breezy, SSW wind 10-15 knots with gusts around 25 knots. A few brief gusts approaching 30 knots are also possible during the afternoon.
Tonight... High Confidence.
VFR, areas of MVFR-IFR are possible across south coast, Cape Cod, and the Islands. SW wind 8-12 knots.
Saturday... Moderate Confidence.
VFR, becoming MVFR with afternoon thunderstorms. Area of greatest risk for strong to severe storms are interior southern New England terminals. Gusty SSW wind 10-15 knots, gusting 25 knots.
KBOS Terminal...Moderate confidence in TAF. Lower confidence in the 12-16z timeframe with ceilings. IFR ceilings developed post showers this morning, but should scatter out in the 14-16z timeframe.
KBDL Terminal...High confidence in TAF.
Outlook /Sunday through Tuesday/...
Saturday Night: MVFR/IFR conditions possible. Breezy. SHRA likely, isolated TSRA, patchy BR.
Sunday: Mainly VFR, with local IFR possible. Chance SHRA, patchy BR.
Sunday Night: VFR. Slight chance SHRA.
Monday through Tuesday: VFR.
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.MARINE... Forecaster Confidence Levels...
Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.
* A Small Craft Advisory is in effect for all waters beginning today and will carry through Saturday evening.
Friday and Saturday... High Confidence.
A few showers are possible overnight into Friday morning and areas or marine fog. Wind shifts to the SSW for today with sustained winds of 15-20 knots, with gusts 25-30 knots through Saturday. Seas on the outer waters are building 4-5 feet and near shore waters are 3-4 feet. A strong cold front will move across the waters late Saturday into Sunday morning, rain and thunderstorms are possible.
Outlook /Sunday through Tuesday/...
Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, isolated thunderstorms, patchy fog. Visibility 1 to 3 nm.
Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft. Rain showers likely, patchy fog. Visibility 1 to 3 nm.
Sunday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers. Local visibility 1 to 3 nm.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Monday Night through Tuesday: Winds less than 25 kt.
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.BOX WATCHES/WARNINGS/ADVISORIES... CT...None. MA...None. RI...None. MARINE...Small Craft Advisory from 11 AM this morning to 7 PM EDT this evening for ANZ230-236. Small Craft Advisory from 11 AM this morning to 8 PM EDT Saturday for ANZ231>235-237-250-251-254>256.
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SYNOPSIS...Frank/Dooley NEAR TERM...Dooley SHORT TERM...Dooley LONG TERM...Frank/Dooley AVIATION...Dooley/Mensch MARINE...Dooley
NWS BOX Office Area Forecast Discussion