NWS Boston/Norton, MA wrote its last area forecast discussion before the first event at May 31, 10:52 AM EST, 8 minutes earlier.
Area forecast discussion, May 31, 10:52 AM EST, 8 minutes before
Area Forecast Discussion
National Weather Service Boston/Norton MA
1152 AM EDT Sat May 31 2025
.SYNOPSIS...
A strong low pressure will bring a round of widespread showers and
scattered thunderstorms with locally heavy rainfall through this
morning. A period of drier weather is expected late morning into the
afternoon before another round of scattered showers arrives later
today into tonight, with a few embedded thunderstorms possible too.
Drier weather follows Sunday into much of next week, except Thursday
and/or Friday, with the risk for scattered showers & thunderstorms.
A warming trend is likely too, with highs in the 80s mid to late in
the week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Key Messages:
* Gusty to Strong Southwest Wind Gusts for Southeast New
England, peaking between 2-7 PM. Wind Advisory issued until 10
PM for gusts 45-50 mph for southeast RI, southeast MA and
Cape Cod/Islands.
* Widely Scattered T-storms mainly in interior Southern New
England to I-95 between 2-7 PM.
Made a few adjustments to the forecast.
Overcast skies early have started to scatter out across
southeast New England, including the Cape and Islands. This has
led to some modest heating/mixing and is leading to
southwesterly gusts in the 35 mph range, even as far north as
Norwood and Boston. However gusts Further southwest in the
cloudy air across Long Island and NYC/northern NJ, gusts of
35-40 kt have been pretty common. NAM/RAP/HRRR profiles show a
southwesterly low level jet moving across the south coast during
the afternoon to early evening, with the NAM showing 975 mb
winds 45-50 kt! As long as we can stay with partial sun, we
should be able to mix a good portion of this jetcore leading to
gusts peaking in the 45-50 mph range. Given that some may have
made it to the beaches with this clearing, we opted for a wind
advisory for these southeast coastal areas until 10 PM.
Also monitoring the potential for re-developing scattered
showers/t-storms mainly in interior Southern New England during
the 2-7 PM timeframe. With cloud cover trending toward more of
scattered to broken cumulus look, modest heating has allowed
for temps to warm into the mid 60s. Additional heating should
allow for a narrow corridor of weak instability (CAPEs 500-1000
J/kg) from about Orange to Hartford eastward to Lawrence and
southward into the Providence area, as sfc low near the
Litchfield Hills pulls NE into north-central MA. Already are a
few deepening cores currently per day-cloud-phase satellite
imagery coming off the Berkshires and into NW Hartford County,
with expectations that this activity and additional scattered
t-storms could develop northeastward following recent
NAM-3km/HRRR trends. Severe weather not expected but lightning
and brief gusts to 40 mph possible in stronger cells.
Previous discussion...
We're in the thick of the much advertised period of widespread rain
showers with some elevated thunderstorms associated with an
anomolous mid level trough which is currently digging into New
England. Mesoscale analysis and WV satellite imagery show the center
of the vertically stacked low directly over the Mid Atlantic where
the heaviest rainfall currently is falling. As this low lifts
directly over SNE the heaviest and steadiest bands of precipitation
will fall to the NW of the low, over western MA and CT. This is
where the most rainfall is expected by the time all is said and done
Saturday evening. We continue to expect generally 1 to 2 inches of
rain, but with locally higher amounts as high resolution guidance
indicates the potential for as much as 3 to 4 inches; at this time
those highest amounts are more likely just to the west of our
region. Regardless, some localized street flooding is possible,
especially under any training cells or convection. Instability is
marginal (up to 500-850 mb) and elevated so not expecting any severe
weather, but rather garden variety thunderstorms embedded in
showers, especially between 8 am and 2 pm. A dry slot eventually
moves over eastern MA/RI bringing an end to widespread rainfall by
mid to late morning. Rain likely continues most of the day further
west. Then, some additional moisture is pulled in on the back side
in the late afternoon/evening as another shortwave rounds the base
of the trough. This may kick off another round of less widespread
showers and an embedded thunderstorm or two, generally along and
northwest of the I-95 corridor. Instability is more limited with
this round (dependent on how many breaks of sun we get) and the
shear environment is unfavorable, so severe weather is not expected.
Showers come to an end by 10 pm with drier westerly flow bringing a
good amount of clearing. Cold advection in the low/mid levels will
support lows in the upper 40s (warmer along the immediate coast.
&&
.SHORT TERM /SUNDAY/...
Key Messages:
* Mainly dry Sunday, but cooler than normal, with highs in the 60s
and lows in the 40s.
Dry on Sunday under westerly flow under slowly rising heights. The
upper trough remains overhead with a cold pool aloft and this
together with lingering low/mid level moisture will lead to a good
amount of diurnal cloud cover. Given the colder air aloft, highs
will be a few degrees cooler, in the mid to upper 60s.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key Messages:
* Mainly dry week ahead, a cold front late in the week brings the
next chance for appreciable rainfall.
* Warming trend this week, Wednesday and Thursday will be summery
with highs in the 80s and dewpoints in the 60s.
Fairly quiet weather on Monday, will have a mixture of clouds as the
region is under cyclonic flow. 850mb temperatures begin to increase,
from +3C Sunday to +7C Monday, resulting in warmer temperatures for
Monday afternoon. Highs are in the upper 60s near the coast to the
lower 70s inland. Monday evening into Tuesday a shortwave pivots
about the departing system, do not expect any precipitation as PWATs
fall to less than 1/2".
Mid-level trough moves off shore Tuesday with rising heights as the
ridge shifts into New England. Dry and warming conditions Tuesday to
Thursday, the one potential issue would be if the ridge pinches off
the departing trough and results in weaker cut-off low east of the
region. Only a few members show this, thus think the warm and dry
conditions will prevail. 850mb temperatures Tuesday increase towards
+8C and +10C, but really increase for Wednesday and Thursday as
those temperatures are +15C to +18C. Should have highs on Tuesday in
the upper 70s to low 80s away from the coast, near the coast those
temperatures are in the lower 70s. Wednesday and Thursday it will be
summer like with highs well into the 80s. Looking for relief the
south coast will likely be a bit cooler in the upper 70s due to the
SSW flow. And with this flow, will have increasing due points into
the low 60s, so will feel muggy as well. As for nighttime relief,
doesn't appear to be much with lows Tuesday/Wednesday/Thursday night
in the low to middle 60s.
Our next chance for rain would come late in the week, late Thursday
or perhaps Friday as a cold front moves in from the northwest.
&&
.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
15z TAF Update:
Today: Moderate confidence.
MVFR/VFR ceilings, lowest categories mainly along/west of ORH.
Possible SCT -TSRA 17-22z HFD/BDL to ORH to BED. SW gusts
strongest over SE MA/RI/Cape and Islands. Gusts at ACK could
reach into the 45 kt range this afternoon, with gusts 35-40 kt
PVD and Cape airports. Elsewhere, SW winds around 10-15 kt with
gusts 25 kt before shifting to W late in the day.
Tonight...High confidence.
VFR. W winds 10-15 kts.
Sunday...High confidence.
VFR. W winds 10-15 kts, gusting to 20-25 kts in the afternoon,
locally higher to 30 kts over the Cape and Islands.
BOS TAF...High confidence in trends. Lower confidence in vsby
potential and timing.
BDL TAF...High confidence in trends. Lower confidence in exact
timing and specific details.
Outlook /Sunday Night through Wednesday/...
Sunday Night: VFR. Breezy.
Monday through Wednesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today...
Winds becoming SW 12-18z today followed by gusts to 25-35 kt
developing, higher to 40 kts possible over southern waters.
Seas building to 8-10 ft over southern waters as well. SCA in
effect for all waters. Showers and sct t-storms moving over the
waters this morning with poor vsbys in fog, with some
improvement developing during the afternoon.
Saturday night...High Confidence.
W winds 15-20 kts with gusts as high as 25 kts. Seas 6-10 ft.
Sunday...High Confidence.
W winds 10-20 kts with gusts as high as 30 kts. Seas 4-7 ft.
Outlook /Sunday Night through Wednesday/...
Sunday Night: Winds less than 25 kt. Local rough seas.
Monday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Monday Night: Winds less than 25 kt. Seas locally approaching
5 ft.
Tuesday through Wednesday: Winds less than 25 kt.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Wind Advisory until 10 PM EDT this evening for MAZ020>024.
RI...Wind Advisory until 10 PM EDT this evening for RIZ005-007-008.
MARINE...Small Craft Advisory until 10 PM EDT this evening for ANZ230-
231-251.
Gale Warning until 10 PM EDT this evening for ANZ232>237-
254>256.
Small Craft Advisory until 8 AM EDT Sunday for ANZ250.
&&
SYNOPSIS...BW/Dooley
NEAR TERM...Loconto/BW
SHORT TERM...BW
LONG TERM...Dooley
AVIATION...Loconto/BW/Dooley
MARINE...Loconto/BW/Dooley