163
FXUS61 KBOX 170613
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
213 AM EDT Tue Jun 17 2025

.SYNOPSIS...
A couple of weak disturbances will bring scattered showers at
times late tonight into Wednesday with a few thunderstorms
possible Wednesday. Cooler than normal temperatures Tuesday
will be followed by a warming trend with hot and humid
conditions Thursday. The heat and humidity will be accompanied
by a chance of thunderstorms, some severe possible, late
Thursday and Thursday evening ahead of a cold front. Then more
seasonable and drier conditions follow for Friday and Saturday.
Looking ahead to early next week, it appears significant heat
may impact southern New England.

&&

.NEAR TERM /UNTIL 6 AM THIS MORNING/...
Key Messages:

* Stratus and patchy fog redeveloping

* Scattered showers possible late

Weak mid level ridging will set up over New Eng tonight with weak
large scale subsidence for most of the night. However, deepening
moisture plume approaches from the west ahead of a weak shortwave so
scattered showers may develop late tonight from west to east.
Otherwise, ridging at the surface will extend west across SNE with
continued low level SE flow providing abundant low level moisture.
Result will be stratus and patchy fog redeveloping and expanding
across the region tonight. Lows will range from 55 to 60.

&&

.SHORT TERM /6 AM THIS MORNING THROUGH 6 PM WEDNESDAY/...
Key Messages:

* Lots of clouds with scattered showers at times Tue and Tue
  night

* Below normal temps Tue but increasing humidity

Tuesday and Tuesday night...

Unsettled pattern developing as a couple weak shortwaves will be
moving through. Meanwhile, an area of deep moisture sets up across
SNE with anomalous PWAT plume increasing to 1.75 to 2 inches.
Forcing for ascent is weak but enough forcing acting on high
moisture will lead to scattered showers moving through. Timing of
these showers is uncertain and not expecting a washout, but there
will be showers at times Tue into Tue night. Not expecting any
thunder but may see some convective showers developing as stability
decreases.

Otherwise, expect gloomy conditions with lots of stratus through the
period. The cloud cover and SE flow will result in cooler than
normal temps Tue with highs upper 60s to lower 70s. Dewpoints will
be climbing into the low and mid 60s so there will be somewhat of a
humid feel to the airmass. A milder night Tue night with lows in the
lower 60s.

&&

.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Messages:

* Becoming hotter each day through Thursday, then cooling off a bit
  Friday through the weekend before our hottest stretch of the year
  early next week.

* Severe weather possible on Thursday, greatest risk is damaging
  winds

* Dry Friday and Saturday but chance for some showers at some point
  in the weekend.

Wednesday and Thursday...

The return of more summer-like warmth comes Wednesday as southern
New England will be sandwiched between high pressure  over the
Atlantic and low pressure moving through the Great Lakes. This
places us beneath warm, moist SW flow until a cold front sweeps
through late Thursday. Before this, 925 temps reach 20C on Wednesday
and near 25C on Thursday which should lead to high temperatures in
the 80s and upper 80s/low 90s respectively. It will also feel very
humid as dewpoints surge into the upper 60s Wednesday and even low
70s potentially by Thursday. Not only will this increase the
apparent temperatures, it will contribute to a great amount of
instability on Thursday; guidance indicates several thousand J/kg of
MUCAPE available. This, combined with mid level lapse rates
approaching 7 c/km and 30-40 kts of 0-6 km bulk shear will lead to a
decent chance of severe weather on Thursday. SREF guidance indicates
a 40-50% probability of CAPE > 1000 J/kg and bulk shear >30kts,
maximized over western and central SNE. Timing and severity will
depend on several factors, including how quickly that cold front
moves through. At this point the ECMWF would indicate a quicker
passage, closer to the peak heating of the day while the GFS is
slower, after sunset. Stay tuned.

Friday through early next week...

Friday into the weekend we`ll be under drier W/NW flow and with a
lingering trough/cyclonic flow aloft leading to some diurnal clouds
Friday and potential for a weak shortwave moving through around late
Saturday/early Sunday which may bring some showers but confidence is
low at this point. What is more certain is that the pattern will be
changing as we go into next week with high confidence of a building
ridge and very hot temperatures for the first half of next week. At
this point both the EPS and GEFS indicate a 70+% chance of 90+F on
Monday and a near certainty by Tuesday.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...
Forecaster Confidence Levels...

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

06z TAF Update:

Through 12z Tuesday: Low to moderate confidence.

A broad mix of VFR-MVFR with even some patchy IFR, with the
lowest categories currently over the interior in some showers.
Forecast guidance has been poor in handling these observed
conditions which renders a low-confidence forecast. Trend will
be for deteriorating conditions where VFR currently exists toward
at least widespread MVFR/intervals IFR by daybreak, with hit-
or- miss light showers that won`t restrict visby. Light E/SE
winds.

Today: Moderate confidence.

Areas MVFR/IFR stratus should improve toward BKN-OVC MVFR bases.
After early-AM showers move east, best chance at hit-or-miss
showers mainly interior but confidence in timing/coverage is
low and may end up being dry for most of the day. SE to S winds
under 10 kt.

Tonight: Moderate confidence.

Deteriorating conditions toward MVFR-IFR with patchy IFR-MVFR
visby fog. A better chance at showers tonight and especially
overnight, which continues to move east and offshore toward
daybreak. SE to S winds 5 kt or less.

Wednesday: High confidence in trends but moderate on exact
timing.

MVFR/IFR stratus from overnight scatters/lifts to BKN VFR
bases, with showers ending early in the day. S/SW winds 5-10
kt.

KBOS Terminal...Moderate confidence in TAF. Current VFR should
deteriorate to MVFR stratus after 08z but the timing and is low
confidence. Categories should linger around MVFR levels most of
the day with any showers being hit-or-miss. E/SE winds 5-10 kt.

KBDL Terminal...Moderate confidence in TAF. MVFR/psbl IFR cigs
with -SHRA thru 16z, then improving to BKN MVFR bases. Light SE
winds.

Outlook /Wednesday Night through Saturday/...

Wednesday: Mainly VFR, with local IFR possible. Chance SHRA,
slight chance TSRA.

Wednesday Night: VFR. Slight chance SHRA, slight chance TSRA.

Juneteenth: VFR. Breezy. Slight chance SHRA, slight chance
TSRA.

Thursday Night: VFR. Breezy. Slight chance SHRA.

Friday: VFR. Breezy.

Friday Night: VFR.

Saturday:

&&

.MARINE...
Forecaster Confidence Levels...

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

Tonight through Tuesday night...

Persistent E-SE winds through Tue gradually becoming more
southerly Tue night. Speeds below 20 kt and seas 2-4 ft. Areas
of fog developing tonight into Tue morning with more fog
possible Tue night. Scattered showers at times Tue and Tue
night.

Outlook /Wednesday Night through Saturday/...

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

Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft. Slight chance of rain showers, slight chance
of thunderstorms.

Juneteenth: Low risk for Small Craft Advisory winds with gusts
up to 25 kt. Areas of seas approaching 5 ft. Slight chance of
rain showers.

Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers.

Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of seas approaching 5 ft.

Friday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.

Saturday: Winds less than 25 kt.

&&

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

&&

$$

SYNOPSIS...Loconto
NEAR TERM...Loconto
SHORT TERM...Loconto
LONG TERM...Loconto
AVIATION...Loconto
MARINE...Loconto