Severe Thunderstorm Warning 58, NWS Boston/Norton, MA

Area Forecast Discussion
National Weather Service Boston/Norton MA
353 PM EDT Tue Sep 13 2022

.SYNOPSIS...

A cold front will bring scattered showers and thunderstorms
into mid-evening with the primary focus shifting from near the
south coast to interior southern New England. This will be
followed by a seasonably warm and dry weather Wednesday, then a
touch of fall for the end of the week with blustery and cool
conditions as high pressure builds in from Canada. The high
pressure moves offshore this weekend bringing warmer
temperatures into early next week.

&&

.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...

345 PM Update...

* A few strong-severe t-storms possible into mid evening mainly
  in western MA/CT but not expecting widespread severe weather

* Dry weather overnight with a sharp decrease in Humidity

The cluster of showers and t-storms that brought torrential
rainfall/street flooding near the south coast, as well as portions
of the Cape & Marthas Vineyard today was finally starting to
decrease in areal coverage. This trend should continue as drier
air continues to work into these region aloft.

Main focus was shifting to a potent shortwave/closed 500 mb low
lifting northeast across the Great Lakes. SPC Meso-Analysis
indicates MLCapes have increased to around 1500+ J/KG across
western MA/CT with 40-45 knots of effective bulk shear. While
this is quite favorable for severe weather; the big limiting
factor is the potent shortwave/closed 500 mb and its associated
forcing was well to our west across the eastern Great Lakes.
This lack of overlap will be a limiting factor for severe
weather this evening. That being said; the pre-frontal and
associated cold front swinging through this evening will
probably be enough to generate scattered showers and t-storms
this evening. The main focus for this will be northwest of I-95
and particularly across western MA/CT; closer to the upper
level support. While a severe weather outbreak is not expected;
a few strong to severe thunderstorms are certainly possible
with isolated strong to damaging wind gusts the main concern.
Again, widespread severe weather is not expected.

Any activity should wind down and come to an end by late
evening. Otherwise...much drier air will work into the region
overnight on westerly winds. Low temps will bottom out in the
middle 50s to the lower 60s in most locations by daybreak.

&&

.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...

Highlights...

* Plenty of sunshine and beautiful Wed with pleasant high temps
  in the middle 70s to the lower 80s and comfortable humidity

* Secondary cold front late Wed night brings a taste of early
  fall weather by daybreak Thu

Wednesday...

A beautiful post-frontal airmass follows on Wednesday. We should
see partly to mostly sunny skies with just some fair weather
diurnal CU; which will be most prevalent across the interior.
850T near +10C should result in highs ranging from the middle
70s in the high terrain with upper 70s/lower 80s elsewhere.
Dewpoints in the 50s will result in comfortable humidity levels
too. High pressure building into eastern Quebec coupled with low
pressure over the Maritimes will result in a decent breeze.
Nothing too extreme but northwest winds will gust to between 20
and 25 mph at times. Overall...a very nice mid-September
afternoon is in store for the region.

Wednesday night...

A secondary cold front will cross the region late Wednesday
night. This front will come through dry, but it will usher in an
even cooler airmass to southern New England. Low temps by
daybreak Thu will generally be in the 50s northwest of the Cape
Cod Canal. In fact may see some upper 40s in northwest MA. This
will not be a radiational type of cooling, but on cool
advection on NW winds. Northwest wind gusts of 15 to 20 mph
expected to develop toward daybreak and up to 25 mph along the
coast and parts of the high terrain. So a taste of early fall
weather will arrive by daybreak Thu.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...

Highlights...

* A taste of true Fall weather arrives for Thursday into the first
  half of the weekend.

* Warming up Sunday into early next week with above normal
  temperatures returning by Monday. Periodic chances for rain return
  starting on Sunday.

Details...

Thursday through Saturday...

A stretch of dry and quite a bit cooler weather arrives for the
latter half of the week and into the first half of the weekend. This
nice weather comes thanks to an exiting trough over Nova Scotia and
a building ridge over the Midwest. It places southern New England
beneath dry and cooler northwest flow advecting in 850 mb temps
around 7-10C. Model soundings indicate mixing up to just under 850
mb which will translate to highs from the upper 60s (interior high
elevations) to the mid 70s (along the south coast) through Saturday.
This is compared to average highs in the mid 70s. Overnight plunging
dewpoints will allow for chilly lows, in the 40s and low 50s.
Placement between a building surface high and low pressure over Nova
Scotia will make for breezy conditions, especially during the day.

Sunday through Tuesday...

A moderation of temperatures begins later Saturday and especially
Sunday as high pressure exits offshore and flow once again becomes
S/SW. While pushing temperatures back above normal on Sunday (into
the upper 70s/low 80s) it also brings the return of more humidity as
dewpoints rise into the low 60s. Indications continue to be that
this is the start of a prolonged warm-up into mid week under a
building ridge, with highs back in the mid-upper 80s Mon and
Tuesday! EPS ensemble guidance is indicating a >60% chance that
we'll be back above the 80s on Monday, a bit less so on Tuesday.
This lines up with CPS's current 6-10 day outlook calling for a 70-
80% chance of above average temperatures during this period. We'll
see a couple of disturbances clip New England, bringing periodic
rain chances first on Sunday then again Monday or Tuesday, but
confidence is low in the details of any unsettled weather.

&&

.AVIATION /19Z TUESDAY THROUGH SUNDAY/...

Forecaster Confidence Levels:

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

18Z TAF Update:

This afternoon and Evening...Moderate Confidence. MVFR-IFR
conditions will dominate into early this evening. Showers and
embedded t-storms with torrential rainfall near the south coast,
Cape and MVY will wind down somewhat by late afternoon.
Otherwise, the focus for scattered showers and thunderstorms
will shift to the interior particularly interior MA & CT after
19z. A few of the storms may become strong to severe with
locally strong wind gusts. Again, this new activity should
focus mainly northwest of I-95 especially western/central MA and
CT. This activity should wind down between 01z and 02z.

Later This Evening and Overnight...High Confidence. MVFR-IFR
conditions should improve to VFR roughly between 00z and 03z
across the interior. This should happen across the coastal
plain generally between 03z and 06z. Otherwise...mainly VFR
overnight outside of some low-lying patchy ground fog, but
should not be widespread given enough wind in the boundary
layer. Winds generally WSW at 5-15 knots.

Wednesday and Wednesday night...High Confidence. VFR other than
some brief marginal MVFR ceilings possible in distant interior
for a few hours in the morning. Otherwise...VFR with just
scattered diurnal CU. WNW wind gusts of 15 to 25 knots during
the daylight hours. Another surge NW wind gusts of 15 to 20
knots should develop toward daybreak Thu behind a secondary cold
front.

KBOS Terminal...Moderate confidence in TAF. Expect main threat
for thunderstorms later this afternoon and evening to remain
west of the terminal. However, the low risk for a t-storm does
still exist.

KBDL Terminal...Moderate confidence in TAF. Main risk for
thunderstorms in the vicinity of the terminal will be between
19z and 00z.

Outlook /Thursday through Sunday/...

Thursday through Thursday Night: VFR. Breezy.

Friday through Saturday Night: VFR.

Sunday: VFR. Slight chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Wednesday night...High Confidence.

A cold front crosses the region tonight. This should bring an
end to the scattered showers and thunderstorms that were
impacting the southern waters this evening. Otherwise...small
craft headlines hoisted for our northern waters beginning late
tonight. NW wind gusts of 25 knots should develop behind the
cold front in the cool advection pattern. While these wind gusts
will diminish for a time Wed afternoon and evening; they should
pick back up toward daybreak Thu behind a secondary cold front.
Therefore...extended the small craft headlines for these waters
and its possible a few additional waters may need to be added.

Outlook /Thursday through Sunday/...

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

Thursday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Friday through Sunday: Winds less than 25 kt.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 1 AM Wednesday to 8 AM EDT Thursday
     for ANZ250-251.

&&

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

Hazardous Weather Outlook
National Weather Service Boston/Norton MA
409 PM EDT Tue Sep 13 2022

CTZ002>004-MAZ002>024-026-RIZ001>008-142015-
Hartford CT-Tolland CT-Windham CT-Western Franklin MA-
Eastern Franklin MA-Northern Worcester MA-Central Middlesex MA-
Western Essex MA-Eastern Essex MA-Western Hampshire MA-
Western Hampden MA-Eastern Hampshire MA-Eastern Hampden MA-
Southern Worcester MA-Western Norfolk MA-Southeast Middlesex MA-
Suffolk MA-Eastern Norfolk MA-Northern Bristol MA-
Western Plymouth MA-Eastern Plymouth MA-Southern Bristol MA-
Southern Plymouth MA-Barnstable MA-Dukes MA-Nantucket MA-
Northern Middlesex MA-Northwest Providence RI-
Southeast Providence RI-Western Kent RI-Eastern Kent RI-Bristol RI-
Washington RI-Newport RI-Block Island RI-
409 PM EDT Tue Sep 13 2022

This Hazardous Weather Outlook is for northern Connecticut, all of
Massachusetts east of Berkshire County, and Rhode Island.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

ANZ230>237-250-251-254>256-142015-
Boston Harbor-Cape Cod Bay-Nantucket Sound-Vineyard Sound-
Buzzards Bay-Rhode Island Sound-Narragansett Bay-Block Island Sound-
Coastal waters east of Ipswich Bay and the Stellwagen Bank National
Marine Sanctuary-Massachusetts Bay and Ipswich Bay-
Coastal waters from Provincetown MA to Chatham MA to Nantucket MA
out 20 nm-
Coastal Waters extending out to 25 nm South of Marthas Vineyard and
Nantucket-
Coastal Waters from Montauk NY to Marthas Vineyard extending out to
20 nm South of Block Island-
409 PM EDT Tue Sep 13 2022

This Hazardous Weather Outlook is for Massachusetts and Rhode
Island coastal waters.

.DAY ONE...Tonight.

No hazardous weather is expected at this time.

.DAYS TWO THROUGH SEVEN...Wednesday through Monday.

No hazardous weather is expected at this time.

.SPOTTER INFORMATION STATEMENT...

Spotter activation is not expected at this time.

For more information on upcoming hazardous weather, please see the
Area Forecast Discussion on our webpage for the latest forecast
thinking. There is also our Enhanced Hazardous Weather Outlook at
www.weather.gov/box/ehwo

For the latest updates...please visit our webpage at
www.weather.gov/boston

You can follow us on Facebook at
www.facebook.com/NWSBoston

You can follow us on Twitter at
@NWSBoston

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Special Weather Statement
National Weather Service Boston/Norton MA
103 PM EDT Tue Sep 13 2022

MAZ023-131800-
Dukes MA-
103 PM EDT Tue Sep 13 2022

...A strong thunderstorm will impact portions of Dukes County through
200 PM EDT...

At 102 PM EDT, Doppler radar was tracking a strong thunderstorm near
Aquinnah, moving northeast at 35 mph.

HAZARD...Minor flooding.

SOURCE...Radar indicated.

IMPACT...Minor nuisance flooding of typically flood prone areas.

Locations impacted include...
Oak Bluffs, Edgartown, Tisbury, Aquinnah, West Tisbury and Chilmark.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Get indoors when you hear thunder. Do not resume outdoor activities
until at least 30 minutes after the storm has passed.

Do not drive through flooded roads or underpasses. Avoid low lying
areas near small streams.

&&

LAT...LON 4125 7082 4126 7083 4132 7077 4132 7080
      4131 7079 4135 7084 4135 7077 4143 7070
      4148 7061 4145 7060 4147 7056 4143 7057
      4139 7050 4136 7050 4139 7048 4137 7045
      4135 7045 4134 7073 4125 7080
TIME...MOT...LOC 1702Z 233DEG 29KT 4129 7091

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...<30 MPH

RM

Special Weather Statement
National Weather Service Boston/Norton MA
522 PM EDT Tue Sep 13 2022

MAZ008>010-132215-
Western Hampshire MA-Western Hampden MA-Eastern Hampshire MA-
522 PM EDT Tue Sep 13 2022

...A strong thunderstorm will impact portions of western Hampshire
and northwestern Hampden Counties through 615 PM EDT...

At 522 PM EDT, Doppler radar was tracking a strong thunderstorm near
Great Barrington, moving northeast at 30 mph.

HAZARD...Winds in excess of 40 mph and penny size hail.

SOURCE...Radar indicated.

IMPACT...Strong winds could cause minor damage such as downed
         branches. Minor damage to outdoor objects is possible.

Locations impacted include...
Northampton, Easthampton, Southampton, Huntington, Westhampton,
Chester, Blandford, Chesterfield, Worthington, Goshen, Cummington,
Montgomery and Middlefield.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Get indoors when you hear thunder. Do not resume outdoor activities
until at least 30 minutes after the storm has passed.

&&

LAT...LON 4239 7305 4238 7301 4243 7300 4249 7287
      4227 7271 4217 7303 4227 7300 4231 7300
      4231 7303 4233 7306 4238 7307
TIME...MOT...LOC 2122Z 245DEG 27KT 4219 7328

MAX HAIL SIZE...0.75 IN
MAX WIND GUST...40 MPH

KC

Special Weather Statement
National Weather Service Boston/Norton MA
531 PM EDT Tue Sep 13 2022

MAZ002-132215-
Western Franklin MA-
531 PM EDT Tue Sep 13 2022

...Strong thunderstorms will impact portions of northwestern Franklin
County through 615 PM EDT...

At 530 PM EDT, Doppler radar was tracking strong thunderstorms along
a line extending from near Monroe to Adams. Movement was east at 20
mph.

HAZARD...Winds in excess of 30 mph and minor flooding.

SOURCE...Radar indicated.

IMPACT...Minor nuisance flooding of typically flood prone areas.

Locations impacted include...
Monroe, Colrain, Charlemont, Leyden, Heath, Rowe and Hawley.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Get indoors when you hear thunder. Do not resume outdoor activities
until at least 30 minutes after the storm has passed.

Do not drive through flooded roads or underpasses. Avoid low lying
areas near small streams.

&&

LAT...LON 4273 7265 4264 7277 4262 7296 4266 7295
      4267 7296 4266 7298 4267 7300 4270 7295
      4270 7302 4274 7302
TIME...MOT...LOC 2130Z 256DEG 19KT 4275 7301 4263 7315

MAX HAIL SIZE...0.00 IN
MAX WIND GUST...40 MPH

KC