NEAR TERM /UNTIL 6 PM THIS EVENING/
Latest SPC mesoanalysis showed convective inhibition from the showers and thunderstorms earlier this morning already started to dissipate. CAPE values recovering somewhat, with most- unstable values between 500-1,000 J/kg. Not seeing a lot of breaks in the clouds upstream, meaning it's not likely to increase substantially heading into this afternoon. Mesoanalysis did show a decent amount of shear. Not enough where there is significant concern for severe weather, but enough where some storms could get stronger.

The main concern heading into this afternoon will be the potential for downpours. Precipitable water values of 2-2.5 inches just signal how humid the air mass is. 12Z soundings did show warm-cloud depths in excess of 10 kft, meaning efficient rainfall processes should be in place. Will need to monitor stronger storms for excessive rainfall this afternoon and evening.

Minor tweaks to temperatures to reflect observed trends.

7:15 AM Update:

First batch of moderate to heavy rain as moved from southeast CT through RI and into eastern MA. KBOX indicated rainfall rates around 2-5 inches per hour, a nod to the impressive PWATs over SNE. Did make adjustments to the hourly POPs to better reflect current radar trends. As previous discussion mentioned, it is a low confidence forecast do to the lack of forcing. Never the less the trends outlined by the previous forecast remain in line with current thinking.

345 AM Update:

Key Points:

* Variable cloudiness, highest south and east, but quite humid!

* Scattered t-storms in CT and western/central MA as soon as noon, but more likely 2-10 PM. Torrential downpours are the main risk, but isolated strong wind gusts are possible.

Bottom line up front: the forecast for today is marred with quite a bit of uncertainty on timing details, especially on potential for re- developing showers/storms this afternoon. In a weak pressure pattern with nebulous forcing mechanisms and a very humid air mass, it won't take much heating to generate at least pop-up showers, and as they typically do in this weakly- forced setting, near-term and high-res guidance are really struggling with run-to-run consistency. Potential exists for changes today, but our best estimate on anticipated conditions is below.

For today...ongoing showers in CT and western/central MA will continue to work their way through Southern New England in isolated to scattered coverage. Could be some downpours in these as they move offshore, but lightning isn't expected. The still- expanding stratus/low clouds from overnight should start to scatter out in most locations by mid to late morning north and west of RI and southeast MA today; but it could take quite a while to scatter out for RI and southeast MA and that leads to somewhat lower temperatures (70s-low 80s) for that portion of Southern New England, as well as low instability. Better heating north and west and especially in the interior seems to favor a second round of scattered showers and thunderstorms moving in from eastern NY or developing over the Berkshires/Litchfield Hills this afternoon. Decent signal across the high-res guidance on this potential, but timing varies. So for PoPs, offered generally dry weather for the mid to late morning in all areas, but a steady increase in PoP to around 30- 50% from Fitchburg to Worcester to Willimantic west. It's a VERY humid airmass and even modest heating in that corridor looks sufficient for CAPE values around 1000-1500 J/kg, falling off sharply further east into eastern MA and SE MA and RI due to the low clouds and slower destabilization. Though we do have pretty good SW flow in mid to upper levels, 0-6 km shear is still on the weaker side. Under assumption storms develop in that airmass, any storm is capable of producing torrential downpours (warm cloud depths are around 13-14,000 ft and PWATs are over 2 inches). I don't think this is a severe weather setup, but we could have isolated stronger gusts through water- loading effects. Eastern extent of this activity in some question but weakening on approach to the BOS-PVD corridor is more likely (if they get that far), and opted to leave these areas dry for the afternoon. Sided highs today in the mid to upper 80s away from the South Coast where there's a better chance at sunny breaks.

SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SATURDAY/
345 AM Update:

Tonight and Saturday:

Any storms from the daytime hrs should shift NE and/or dissipate early tonight. Thinking tonight should be dry for the vast majority of the time, but with the very humid airmass, I couldn't rule out a shower at any time. Kept PoPs around the 20-30% range for tonight. There are some signals in the GFS/FV3 solutions for another round of showers/storms toward daybreak into the western counties, but guidance is again pretty mixed in general on that outcome. Thus couldn't justify going any higher with PoP. We should see expanding fog and stratus again tonight, potentially across a wider portion of Southern New England. Kept lows in the low to mid 70s with expected overcast and the very humid air.

For Saturday there's again quite a diversity in outcomes when it comes to timing of showers and storms, associated with a weak impulse in the SW flow aloft. The GFS shows two potential rounds, one in the morning and the other late in the day, while the NAM solutions favor a more early to mid afternoon timing.
It's not likely to be raining the whole day, but western areas again have a little better chance at showers and thunderstorms than east. Kept a rather broad brushed 30-60% PoP, lowest east and higher west. Will need to wait to see how today's convection unfolds before there's really any confidence in timing. Early overcast should give way to partial clouds by late morning with similar highs to today.

LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/
Highlights:

* Weak front brings showers and storms, mainly to northwestern areas Saturday night and diminishing by Sunday morning. Sunday morning could feature areas of coastal stratus and fog.

* Drier Sunday and Monday, although a slight chance Sunday afternoon for a spot shower or thunderstorm remains. Still rather warm and muggy both days.

* Summer heat and humidity continues into next week with additional rain chances starting later on Tuesday.

Saturday Night:

A front/cool(ish) front associated with mid-level shortwave energy moves across northern New England with showers and thunderstorms. As we've been mentioning, PWATs are anomolous for southern New England, forecasts continue to indicate values between 2.0 to 2.3 inches.
05/00z NAM 3km shows a robust line, but signs it will decay after exiting Vermont and New York. Greatest forcing to the north, plus the forecast lapse rates diminish to next to nothing 00z-03z Sunday.
The better chance for any severe weather would be far northwestern Massachusetts, but severity should quickly diminish as these storms move into a stable airmass.

Unfortunately this is not a strong front, will not bring much if any relief from the high dew points. The front/boundary could stall over the coast waters and be a region for a few spot showers into early Sunday morning.

In addition, high dewpoints and air temperatures in the upper 60s (north) to the mid 70s (south) could spell areas of coastal stratus and fog to start Sunday morning.

Sunday and Monday:

Southern New England is on the outer periphery of a mid-level ridge which is anchored over Bermuda. Do think most of this time we are dry, but with bouts of shortwave energy riding the outer periphery of the ridge, cannot rule out a spot shower/thunderstorm. Have kept a mention of 'slight chance' POPs Sunday afternoon, mainly across the interior as we would expect the terrain to influence the development. As for Monday, likely dry with even less forcing from weak shortwave energy.

With more in the way of sun, should see temperatures rebound back into the upper 80s and lower 90, while the coast sits in the lower to middle 80s. Dew points are still elevated, but a far cry from the middle 70s, look for dews in the upper 60s and lower 70 both days. A heat index could push the mid 90s for places in locations such as the Connecticut River Valley and I-495 corridor. No heat headlines expecting at this time due to the criteria, heat index of 95F to 99F for two consecutive days. Never the less, it will be plenty warm!

As for the overnights, its warm with lows in the upper 60s and the lower 70s around the populated urban centers.

Tuesday through late next week:

Another warm and muggy day for Tuesday, expecting highs in the upper 80s to lower 90s, away from the coast. Dew points are elevated and returning to the low 70s! The heat index to return to the lower and middle 90s. But feel this heat falls just short of needing any heat related headlines. Still a few days out, it is possible things could change. With rain and clouds mid to late week temperatures fall back a few degrees to the low and middle 80s on Wednesday and Thursday.
Still, there is no relief from the summer humidity with dew points remaining elevated, upper 60s to middle 70s.

Becoming unsettled late Tuesday with mid-level heights falling and bursts of shortwave energy ahead of a more robust shortwave that will be over the eastern Great Lakes. This feature does moves east with a broad mid-level trough overnight. Return of showers and storms as early as Tuesday afternoon and continues into the overnight hours. Mid-levels over the northeast are quasi-zonal and will allow for additional bursts of shortwave energy to pass through and produce showers into Thursday. As we've mentioned before, do not expect wall-to-wall rain, rather both periods of rain and periods of dry weather. As for the overnights, its warm with lows in the upper 60s and near 70F around the populated urban centers.

AVIATION /14Z FRIDAY THROUGH TUESDAY/
Forecast Confidence Levels:

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

Today: Moderate confidence overall, but low on timing.

Main aviation concerns this period revolve around timing improvement, if any, of stratus and then SCT SHRA/TSRA for central and western airports. MVFR-LIFR stratus is likely to begin this morning for most, and while we should start to see SCT-BKN MVFR bases for most by 15z, sites such as BOS, PVD and the Cape airports could struggle to see much improvement. There looks to be a period of TSRA today in western New England as skies start to scatter, but confidence in the timing is lower than normal. Heavy downpours likely in TSRA. SW winds today around 5-10 kt.

Tonight: Moderate confidence overall, but low on timing.

Any TSRA for central/western airports to weaken thru 02z; dry weather should prevail for several hours, but we could see another round of SHRA/TS for these same areas later tonight/overnight. Deterioration toward a widespread IFR- LIFR tonight into overnight but timing uncertain. Light S winds.

Saturday: Moderate confidence overall, but low on timing.

IFR-LIFR generally improves to SCT-BKN VFR, but seems to be a better chance at TSRA on Sat especially ORH-PVD north and west.
Timing of TSRA uncertain and subject to adjustment. SW winds 4-8 kt.

KBOS TAF...Moderate to low confidence. IFR CIGs likely to continue for much of today, with a brief period of MVFR CIGs between 15z-18z. Steady south winds around 10 knots. Additional showers and thunderstorms are possible this afternoon, but confidence is too low to include in TAF at this time. CIGs remain IFR to LIFR overnight into Saturday morning.

KBDL TAF...Moderate to low confidence. IFR CIGS this morning improve to MVFR around 15z, with the potential of MVFR BKN CIGs around 20z-00z. Will have chance of thunderstorms this afternoon, but confidence was too low to include at this time.
Tonight, CIGs fall back to IFR. South winds around 10 knots.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Mainly IFR, with local MVFR possible. Breezy.
Chance SHRA, chance TSRA, patchy BR.

Sunday: Mainly VFR, with local IFR possible. Slight chance SHRA, slight chance TSRA.

Sunday Night through Monday Night: VFR.

Tuesday: VFR. Slight chance SHRA, slight chance TSRA.

MARINE
Forecaster Confidence Levels:

Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

Today through Saturday: High Confidence.

Persistent SW flow with winds around 10-15 kt through the period, and seas could get near 5-ft thresholds given the long SWly fetch. Still think it is borderline for SCAs. Morning showers dissipate by late-morning, with fog and stratus tonight over the waters. Better chance for showers and storms over the southern waters on Saturday, but widespread storms not expected.

Outlook /Saturday Night through Tuesday/...

Saturday Night: Winds less than 25 kt. Areas of seas approaching 5 ft. Chance of rain showers, chance of thunderstorms, patchy fog. Visibility 1 to 3 nm.

Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Chance of rain showers, slight chance of thunderstorms, patchy fog. Local visibility 1 to 3 nm.

Sunday Night: Winds less than 25 kt. Seas locally approaching 5 ft. Slight chance of rain showers.

Monday through Tuesday: Winds less than 25 kt.

BOX WATCHES/WARNINGS/ADVISORIES
CT...None.
MA...None.
RI...None.
MARINE...None.