Updated: 225 AM EDT Sat Jul 12 2025
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Seasonably warm and humid conditions continue this weekend. Chance for showers and thunderstorms across the interior today, then trending drier for Sunday. A better chance at showers and thunderstorms then exists on Monday as a frontal system moves through. Increasing heat and humidity around the middle of next week, which then looks to break around Friday as a cold front brings risk for showers and thunderstorms.
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THROUGH TODAY
Key Points
*Continued warm and humid conditions *Isolated showers and thunderstorms are possible once again across the interior
Very little change in airmass on Saturday as high pressure remains parked just off shore. Surface winds turn more ESE as a result of the high pressure, but with dry air offshore, not expecting low clouds and fog to persist all day, with the exception over the Cape and Islands. High temperatures today top out in the low to mid-80s with partial sunshine. Mid-level flow begins to turn more SW late across western MA and into NY and VT. This will help establish a weak convergence boundary that could bring Isolated showers and thunderstorms to the interior. 00z Hi-res guidance has trended this activity further west, remaining in NY and VT.
With 1000-1500 J/kg of MLCAPE and a relatively light cap, I wouldn't be surprised to see some thunderstorms across the western interior near the high terrain. The severe threat still appears limited, with little to no shear and mid-level lapse rates of around 5 C/km. PWATS are a bit higher today compared to yesterday, around 1.5 inches. Some cells produced 2-4 inches of rain in a relatively short period yesterday, prompting a couple of flash flood warnings. Assuming storms form in the western interior today, there is a risk for more heavy rain and flash flooding. 00z HREF highlights much of the western interior with a 30-50% chance to receive 1 inch of rain in 3 hours and a 10% chance to receive 3 inches of rain in 3 hours.
TONIGHT THROUGH 6 PM SUNDAY
Key Points
*Mild with fog again tonight *Dry with seasonably warm and humid conditions on Sunday
Tonight:
Another mild night with low temperatures bounded by dewpoints in the low to mid-60s. More low clouds and fog form shortly after sunset again with light ESE onshore flow.
Sunday:
Very little change in airmass on Sunday as high pressure remains offshore over the Gulf of Maine and a mid-level ridge over the region. High temperatures once again warm into the low to mid-80s, with dewpoints still in the mid-to-upper 60s. Storm chances are lower Sunday as the axis of instability moves further north with the convergence boundary. This leaves SNE capped under the subsidence inversion from the mid-level ridge.
Skies turn mostly sunny after the morning fog and stratus burn off. .
SUNDAY NIGHT THROUGH FRIDAY
Key Messages:
* Better chance at more widespread showers/t-storms Monday, although lower instability values should limit potency of these showers/storms.
* Very warm to hot during the middle of next week, with elevated heat indices around 95-100F.
* Cold front Friday brings a break from the heat and humidity, but also a risk for thunderstorms.
Details:
Monday:
It still looks like Monday offers a better chance at showers and thunderstorms across a wider portion of Southern New England than compared to the weekend, as a stronger shortwave trough in midlevels and an associated sfc front cross the area during the afternoon to early evening. Still pretty weak wind fields overall, albeit a touch stronger than prior days.
Instability values are also still on the lower side. Wouldn't rule out a stronger cell or two but thinking any storms would be more garden-variety than otherwise. Highs are generally similar in the middle 80s, but will be accompanied by increased humidity levels.
Tuesday through Thursday:
Warming temperatures and increased levels of humidity are anticipated for this period, as shortwave ridging aloft builds over and just east of Southern New England. This should bring increasing heat indices to elevated levels, in particular for Wed and Thurs. Both days could feature heat indices approaching Advisory thresholds in the mid 90s to low 100s, highest in the CT and Merrimack Valleys. High temps stand to reach into the upper 80s to mid 90s away from the coast.
It looks as though this period is generally dry with subsidence aloft governing our weather.
That said, there are still a smaller minority of GEPS/EPS members which show some unsettled weather emanating from the mid-Atlantic offshore waters/Gulfstream current moving off towards the NE. Were this to transpire, it could bring a risk for cloudiness and some showers. With fewer ensemble members offering this potential, this wetter outcome isn't currently reflected in the forecast, but may need to be re-considered if there are more ensemble members which show rainier conditions.
Friday:
Friday could feature another day of elevated heat and humidity, but most of the ensemble means show an approaching cold front with higher-end Chance PoPs for showers and thunderstorms coming in during the afternoon. Flow aloft is seasonably strong and could point to a few stronger storms around as the front sags southward but still enough time to drill into those details in the coming days ahead..
Forecaster Confidence Levels...
Low - less than 30 percent. Moderate - 30 to 60 percent. High - greater than 60 percent.
06z TAF Update:
Rest of Tonight: High Confidence
IFR/LIFR stratus and fog continue to move north and overspread much of the region.
Saturday: Moderate confidence.
With little change to the weather pattern, expecting low stratus and fog to lift and burn off around the same time it did yesterday, between 12-15z with the exception of the Cape and Islands where CIGS may remain low all day.
VFR with pockets of MVFR again with lingering low level moisture. Chance for scattered showers and thunderstorms again this afternoon, although recent guidance has trended the activity further west. Went with prob30 for TSRA at western terminals for now, but future shifts may consider removing.
Saturday Night: Moderate confidence.
More IFR/LIFR Stratus builds north under light ESE flow.
KBOS Terminal...High confidence in TAF.
IFR/LIFR CIGS through about 15z again, then VFR/MVFR through the afternoon. Low stratus deck likely again tonight.
KBDL Terminal...High confidence in TAF.
MVFR/IFR through about 13z, then CIGS gradually improve to VFR. Chance for thunderstorms again late this afternoon/evening, but the threat has trended further west.
Outlook /Sunday Night through Wednesday/...
Sunday Night: Mainly VFR, with local IFR possible.
Monday: Mainly VFR, with local MVFR possible. Chance SHRA, chance TSRA.
Monday Night: VFR. Slight chance SHRA, slight chance TSRA.
Tuesday through Wednesday: VFR.
Forecaster Confidence Levels...
Low - less than 30 percent. Medium - 30 to 60 percent. High - greater than 60 percent.
Today through Sunday...High confidence.
Weak pressure gradient will keep winds/seas below small craft advisory thresholds through Sunday: seas 2-4 ft with E winds over the southern waters and SE winds over the eastern waters up to 15 kts during the afternoon hours, remaining light in the overnight hours. Main concern for mariners will be areas of fog tonight that may redevelop Saturday night.
Outlook /Sunday Night through Wednesday/...
Winds less than 25 kt.