750
FXUS61 KBOX 261109
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
709 AM EDT Sat Apr 26 2025

.SYNOPSIS...
Periods of rain with embedded downpours continue through at least
the first part of the day today. A few thunderstorms are possible
for western areas but severe weather is not likely. A cold front
then ushers in a much cooler airmass tonight. Cloudy, cool, and
blustery conditions on Sunday. High pressure returns with dry
conditions for Monday and Tuesday, along with mild to warm
temperatures. A cold front moves across the region on Wednesday with
a few showers possible late Tuesday night into early Wednesday
morning. Seasonable temperatures to end the week with the next
chance for rain by Friday.

&&

.NEAR TERM /THROUGH TONIGHT/...
Key Messages...

* Rain moves offshore, but eastern MA and RI may struggle to reach
  the lower 60s with overcast skies persisting.

* A few t-storms possible west of Worcester this afternoon, but
  severe weather is not likely.

* Cooler and breezy overnight.

Isentropic forcing continues to produce widespread light rain
showers over southern New England early this morning, though the
heavier precipitation remains over eastern PA/NY. This is where, not
coincidentally, mesoanalysis indicates the core of a 40+ kt 850 mb
jet. As this jet (and associated forcing) shift east the heavier
bands of rain will move through SNE generally between 7 AM and 5 PM.
Once all is said and done most locations will have gotten a good
soaking, between a 0.25" and 1.25" with the QPF bullseye over
western/interior SNE; ensemble guidance paints a 60-70% chance of
AOA 1" in the Worcester Hills and 80-95% chance in the Berkshires.
Some dry mid/upper level air works in by afternoon as the core of
the jet moves off, so more breaks in the rain are expected,
especially west, before a final round of showers and thunderstorms
accompanies the cold front late afternoon/evening. Guidance
continues to be pessimistic on breaks of sun during daylight hours
(needed to increase the modest instability available, up to 500 J/kg
SBCAPE) so severe weather is not expected. However, some
thunderstorms are possible, mainly west of Worcester.

Tonight the cold front ushers in a much cooler and drier airmass as
dewpoints drop from 60F to the 30s by 5am. It will become breezy,
however, as CAA promotes deeper mixing. Low temps will be 10+
degrees cooler than the previous night, in the 40s.

&&

.SHORT TERM /SUNDAY/...
Key Messages...

* Cool and blustery conditions on Sunday

Sunday will be drier, but still cloudy thanks to the -23C 500mb cold
pool and cyclonic flow aloft with the lingering trough. Strong
gradient winds will also be increasing through the day as CAA
promotes mixing down of a potent 45-50 kt 850 mb LLJ. A marginal
Advisory may be needed for a portion of interior SNE. Most locations
will be dry on Sunday, but a few instability showers are possible
and some orographically forced precipitation may linger over the
Berkshires for part of the day.

&&

.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key Messages:

* Much warmer with dry conditions Monday and Tuesday. A few showers
  are possible Tuesday night into Wednesday morning ahead of an
  approaching cold front.

* Near seasonable temperatures Thursday and Friday. While Thursday is
  dry, rain chances return for Friday.

Sunday Night: Gusty NNW winds continues for part of the night, but
the duration of the wind will largely depends how quickly we cool
the boundary layer and lose the mixing. Guidance does show a robust
850mb jet with wind speeds aloft 50 to 60 knots, with the 00z NAM
being the most robust with max wind speeds ~70 knots. While I do not
think will mix up to 850mb, BUFKIT soundings mix upward 900mb which
have winds close to 40 knots. For now, think wind gusts 30 to 40 MPH
through midnight is a good assessment, with potentially near advisory
level gusts 46+ MPH for the Berkshire high terrain. Otherwise, the
mid-level low moves out to the Gulf of Maine and drier air advects
into southern New England, will have clearing skies and lows in the
40s and possible upper 30s for those AOA 1,000 feet.

Monday through Wednesday: After a gloomy weekend, nicer weather for
Monday and Tuesday with high pressure and mid-level ridging. Monday
night there is the potential for cooler temperatures because of
radiational cooling, did blend in the cooler CONSMOS guidance which
gave lows are in the upper 30s to low 40s across interior southern
and known areas that radiate well along the I-495 corridor and
Martha`s Vineyard, elsewhere middle and upper 40s. The axis of the
ridge shifts east Tuesday evening and a northern stream trough and
cold front approaches from the west. Temperatures rebound nicely
both these days, low 70s for Monday, then mid to upper 70s on
Tuesday. SW flow on Tuesday ushers in higher PWATs, ahead of an
approaching mid-level trough and surface cold front. While a few
showers Tuesday night into Wednesday morning are possible, it looks
the best forcing with the cold front comes too late as the best
moisture exits east of New England before the cold front arrives.
The timing of the cold front will dictate the high temperatures for
Wednesday, thinking it could be a slow moving front, which may allow
the coast plain to warm up nicely into the low and middle 70s, while
those interior locations only reach the upper 60s to low 70s. Cold
front moves across the region and brings a shot of colder air across
all of southern New England, widespread upper 30s to low 40s.

Thursday and Friday: Drier Thursday with weak high pressure briefly
in control, but is quickly followed by unsettled weather and the
return of rain on Friday. Temperatures late week are seasonable in
the low and middle 60s.

&&

.AVIATION /11Z SATURDAY THROUGH WEDNESDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

12Z TAF Update:

Today: Moderate confidence.

Widespread MVFR/IFR in bands of steady moderate rain, which
begins to move offshore around 18-20z. By then, clouds scatter
to VFR-MVFR (perhaps still some straggling IFR along the south
coast). Possible SCT SHRA/TS near/west of ORH after 20z Sat,
although development and strength of any TS would depend on how
quickly we see any breaks in OVC. If we do see any storms, they
would likely be weakening as they move east of ORH. S/SW winds
around 10-15 kt with occasional gusts to low 20s-kt range.

Tonight: High confidence.

Improvement toward SCT-BKN VFR with cold frontal passage,
though some MVFR bases may develop overnight in western
airports. Winds become W/WNW around 10-15 kt with gusts 25 kt
(up to 30 kt high terrain).

Sunday: High confidence.

VFR. NW winds 10-15 kts.

KBOS TAF...High confidence in TAF thru 07z, then moderate to low.

VFR with E/SE winds continuing thru 03z before becoming S
around 10 kt. Mainly MVFR bases with 3-6SM RA developing after
10z Sat, possibly IFR at times. RA ends ~18-20z with slow
improvement in cigs to borderline VFR levels. Another round of
showers and perhaps a rumble or two of thunder is possible late
afternoon to early evening

KBDL TAF...High confidence in TAF thru 05z, then moderate to low.

VFR with south winds around 10 kt. MVFR-possible IFR bases with
3-6SM RA developing after 09z, then tapering off around early
to mid afternoon. Possible SCT SHRA/TS after 20z depending on
how quickly improvement develops from AM rains.

Outlook /Sunday Night through Wednesday/...

Sunday Night: VFR. Windy with gusts up to 35 kt.

Monday: VFR. Breezy.

Monday Night: VFR.

Tuesday: VFR. Breezy.

Tuesday Night: VFR. Breezy. Slight chance SHRA, isolated TSRA.

Wednesday: VFR. Breezy.

&&

.MARINE...
Forecaster Confidence Levels:

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

Southerly flow continues to strengthen into the SCA range for today,
with winds 25-30 kt and seas 4-7 ft. Rain and reduced visibilities
expected until a sharp frontal passage this evening, bringing a
windshift to W/NW around 15-25 kt. Sunday NW winds will gust 20 to
25 kts with seas of 3-6 ft.

Outlook /Sunday Night through Wednesday/...

Sunday Night: Moderate risk for Small Craft Advisory winds with
local gusts up to 30 kt. Local rough seas.

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

Monday Night: Winds less than 25 kt.

Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas locally approaching 5 ft.

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

Wednesday: Low risk for Small Craft Advisory winds with gusts
up to 25 kt. Local rough seas.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Sunday for ANZ231>237.
     Small Craft Advisory until 2 AM EDT Monday for ANZ250-254>256.

&&

$$

SYNOPSIS...BW/Dooley
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...Dooley
AVIATION...BW/Dooley
MARINE...BW/Dooley