


Area Forecast Discussion
Issued by NWS Boston, MA
Issued by NWS Boston, MA
Versions:
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
-- Highlight Changed Discussion --
-- Discussion containing changed information from previous version are highlighted. --033 FXUS61 KBOX 101407 AFDBOX Area Forecast Discussion National Weather Service Boston/Norton MA 1007 AM EDT Thu Jul 10 2025 .SYNOPSIS... Moderate to heavy rain this morning, tapering off this afternoon. Not as warm today, but still very humid with dewpoints in the 70s. Warmer and drier conditions return Friday, continuing through the weekend before summertime heat and humidity make a return for the start of the week along with unsettled conditions. && .NEAR TERM /UNTIL 6 PM THIS EVENING/...-- Changed Discussion --Key Points... * The significant Flash Flooding south of Boston will improve over the next few hours * Bulk of rain exits the coast by mid-afternoon * An isolated shower/t-storm or two possible late this afternoon/early evening in the distant interior...otherwise mainly dry once this steady rain departs Details... A swath of 4-5"+ of rain fell within a few hours just south of Boston. This resulted in significant flash flooding...especially in the Sharon, to Braintree, to the Milton and Quincy areas. While it was still raining in this region...the hourly rates have come down quite a bit. So no additional Flash Flooding is expected and conditions should improve through mid-afternoon. In fact...the shortwave that brought the pockets of torrential rainfall and flash flooding south of Boston will be departing through early afternoon. The bulk of the rain should depart the coast by mid afternoon...but may linger a bit longer near the south coast. Given the above...we should be able to drop the Flood Watch shortly. Otherwise...mainly dry weather the rest of the day with highs generally in the 70s perhaps flirting with 80 in the CT River Valley. Subsidence behind this shortwave will generally keep us dry in to the early evening...but enough instability may generate a spot shower/t-storm across the distant interior and that being mainly towards the Berks.-- End Changed Discussion --&& .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM FRIDAY/... Key Points * Mainly dry with warm and humid conditions * Low chance for a isolated strong to severe thunderstorm across western MA and CT The low-pressure system moves offshore with rising heights and drier air aloft moving in for Friday. Unfortunately, the drier air aloft is unlikely to bring relief to the 70-degree dewpoints on Friday. High temperatures warm in the 80s with heat indices approaching 90F. Skies start mostly cloudy Friday, but clouds begin to scatter out in the afternoon, which could allow for a couple of isolated thunderstorms to form if it can overcome the subsidence aloft. Again, the environment supports the possibility for pulse severe thunderstorms with instability nearing 1000 J/kg, but with less than 30 knots of shear. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... Key Messages: * Trending drier through the weekend * Summertime heat and humidity return early next week, with highs in the upper 80s to low 90s possible Monday through Wednesday * Daily chances for isolated, non-severe showers and thunderstorms Saturday and Sunday After a wet and unsettled week, well begin transitioning to drier weather this weekend as an area of high pressure settles over the coastal waters to our east. This will support east/southeast flow through Sunday, resulting in relatively cooler temperatures (upper 70s to low 80s) east of I-495 along with sunny and dry conditions. Across the interior, temperatures will be near normal, with daily highs in the mid to upper 80s. Elevated dewpoints in the upper 60s to low 70s will support diurnal instability west of I-495, leading to a slight chance of a pop-up afternoon shower or thunderstorm across the interior this weekend. At this time, there are no signals indicating a risk for severe thunderstorms, as weak wind fields should suppress the wind shear needed to support deep moist convection. Any storms that do develop should collapse relatively quickly. Minimal, if any, thunderstorm activity is expected across eastern areas, as onshore flow/marine air should help stabilize the atmosphere. Monday through Wednesday Prevailing southwest flow returns on Monday, which will support rising temperatures across southern New England. Highs will reach the mid to upper 80s on Monday. A few scattered thunderstorms may also develop across the interior, as a pulse of shortwave energy could move through the Northeast Monday afternoon. There is still no strong signal for the presence of deep-layer wind shear needed to support severe weather, but some uncertainty remains this far out. By Tuesday, ensemble guidance suggests increasing heat, with a 40 to 50% chance of high temperatures exceeding 90 degrees across southern New England on both Tuesday and Wednesday. While there is no clear signal for widespread precipitation during the middle of next week, the typical slight chance for a diurnal thunderstorm remains possible. Stay tuned for further details. && .AVIATION /14Z THURSDAY THROUGH MONDAY/...-- Changed Discussion --Forecaster Confidence Levels... Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent. 12Z TAF Update... Thursday...Moderate confidence. IFR/LIFR with moderate to heavy rain continuing across eastern terminals through 12-15z, 15-18z for the Cape and Islands. Lingering light rain likely continues past 18z in the east, meanwhile, western terminals could see isolated thunderstorms in the late afternoon, closer to 20-23z, but confidence low at this time. Unlikely cloud cover clears enough across eastern terminals for afternoon thunderstorms. Thursday Night... IFR/LIFR ceilings return with light/variable easterly. Some showers/storms possible along the south coast. Friday... Conditions gradually improving to VFR by late morning/early afternoon. KBOS Terminal...High Confidence LIFR/IFR ceilings likely for most of the day. Moderate to at times heavy showers continue through mid-morning and becomes lighter thereafter. LIFR settles back in gain tonight with onshore flow KBDL Terminal... High Confidence MVFR/IFR this morning with some light to moderate showers. Improvements to VFR likely by late morning/early afternoon. Isolated thunderstorms possible this afternoon, mainly after 20-21z. MVFR/IFR returns overnight. Outlook /Friday Night through Monday/... Friday: Mainly VFR, with local IFR possible. Friday Night: VFR. Saturday: VFR. Slight chance SHRA, slight chance TSRA. Saturday Night through Sunday: VFR. Sunday Night: Mainly VFR, with local IFR possible. Slight chance SHRA. Monday: Mainly VFR, with local MVFR possible. Chance SHRA, chance TSRA.-- End Changed Discussion --&& .MARINE... Forecaster Confidence Levels... Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent. Thursday to Thursday Night: Moderate confidence. Strong thunderstorms crossing the waters this morning. Gusts of 40-50 knots possible with heavy rain and near zero visibility. Rain continues for much of the day, tapering off this evening. Low clouds and fog continue through tonight. Winds 10-15 kts out of the SSE on the southern waters and out of the E to NE on the eastern waters. Winds closer to the shores along the south coast may be more NE. Seas 2-4 ft. Outlook /Friday Night through Monday/... Friday: Winds less than 25 kt. Patchy fog. Friday Night through Monday: Winds less than 25 kt. && .BOX WATCHES/WARNINGS/ADVISORIES...-- Changed Discussion --CT...None. MA...Flood Watch until 4 PM EDT this afternoon for MAZ005>007- 013>021. RI...Flood Watch until 4 PM EDT this afternoon for RIZ005-007. MARINE...None.-- End Changed Discussion --&& $$ SYNOPSIS...KP/RM NEAR TERM...Frank SHORT TERM...KP LONG TERM...RM AVIATION...RM MARINE...KP