Gale Watch 7, NWS Boston/Norton, MA

Area Forecast Discussion
National Weather Service Boston/Norton MA
1204 AM EST Wed Mar 5 2025

.SYNOPSIS...
A frontal system brings a period of soaking rains, brief strong
southerly wind gusts, and unseasonably mild temperatures later
Wednesday into early Thursday morning. Then a strong but dry
cold front brings more seasonable temperatures, but also a
period of strong northwesterly wind gusts Thursday night through
Friday. Trending drier and slightly cooler than normal for this
weekend into early next week.

&&

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

* Dry & milder tonight...lows in the 30s to near 40

Anomalously strong low pressure over the plains will lift
northeast towards the Great Lakes tonight. In response, upper
level flow will become more meridional across our region. In
fact, a modest southwest LLJ will keep winds from decoupling
in most locations and significantly milder temps than the last
few nights. Overnight lows should only bottom out in the 30s to
near 40 along with a scattered to broken deck of mid level
cloudiness.

&&

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

* A few spot showers poss across the interior into mid Wed
  afternoon
* Soaking rain arrives late Wed afternoon/evening from west to
  east
* Breezy to windy later Wed/Wed night with mild temps upper 40s
  & 50s
* Wind Advisories may be needed Wed night near and southeast of
  I-95

Details...

Strong surface low pressure lifts northeast across the Great
Lakes Wed. The warm advection process may result in a few spot
showers across the interior during the morning/mid afternoon
hours, but the majority of this period will be feature dry but
mostly cloudy weather. This a result of the main dynamics
remaining well west of the region. Despite the clouds, southwest
flow and good mixing with 925T on the order of +7C/+8C should
result in spring-like high temperatures into the 50s across much
of the region. In fact, temps will remain in the upper 40s and
50s for much of Wed night with strong southerly flow out ahead
of this vigorous system.

The low pressure system over the eastern Great Lakes late Wed
will eventually move into Quebec later Wed night. In response,
forcing for ascent will increase and allow widespread showers to
move into the region late Wed into Wed evening from west to east
and persist overnight. A strong southerly LLJ of 70-80 knots
coupled with Pwats around 1.25 inches, which are both 3-4
standard deviations above normal for this time of year will
sweep across southern New England. These ingredients are
favorable for a period of heavy rain. Fortunately, the system is
progressive but still expect widespread rainfall totals of 0.50
to 1.50 inches with perhaps a few localized higher amounts. We
can not even rule out a rumble or two of thunder, but confidence
was not high enough to insert into the forecast at this time.

The other issue will be a period of strong southerly wind gusts.
Although it will be breezy during the day Wed, the strongest
winds will cross the region Wed evening and into the overnight
hours. These southerly LLJ cases are always tricky as a result
of the inversion. The NAM is indicating the potential of an 80+
knot low level jet at 850 mb moving across the region Wed night.
There are some modest pressure falls too...which sometimes can
assist in winds reaching the surface. Thinking best shot for
this is near and southeast of I-95. In fact, the CIPS analogs
have some modest probs of 40+ knot wind gusts and even a low
risk for 50+ knot wind gusts. We are thinking right now the
potential for southwest wind gusts of 40-55 mph are possible
for a 1-3 hour period, particularly with any convective showers.
Given its 3rd period will let the next shift decide on Wind
headlines, but one may be needed near and southeast of I-95.

&&

.LONG TERM /THURSDAY THROUGH TUESDAY/...
Key Messages:

* Period of strong northwest wind gusts Thu night and Fri. Wind
  headlines likely for at least some of southern New England and
  the coastal waters.

* Still monitoring potential storminess late this weekend, but
  may pass too far offshore for any impacts. Trending colder by
  this weekend into Monday.

Details:

Much of this portion of the forecast exhibited rather good
agreement overall. Expecting the southern stream of the mid
level flow to be dominant and nearly zonal across the southern
tier of the USA. The impact of this will be to steer the
majority of weather systems past our region to the south. The
northern stream of the mid level flow looks more variable. At
some times helping to steer weather features to our south, and
sometimes trying to drag them farther north. The ebb and flow of
the northern stream will have the biggest impact on our
temperatures.

Anticipating above normal warmth Thursday to trend closer to
normal Friday into Monday. Some signs that above normal warmth
could return towards next Tuesday, but much will depend on which
side of a nearly stationary front trapped between two high
pressures we get stuck on. At present, thinking this front will
be just north of the northern MA border. It will not take much
of a shift south to alter the forecast significantly.

Still anticipating a period of stronger winds Thursday night
into Friday as a low pressure over southeast Canada deepens
considerably during this time. The strongest gusts around
Worcester County and into the Berkshires/CT Valley region. A
second surge of gusts is likely Friday at the lower elevations
once daytime mixing gets going. Wind Advisories seem likely to
be needed at least for the higher terrain areas and may gust up
to near High Wind criterion Thurs night. It is a little more
borderline regarding wind headlines at the lower elevations,
but nonetheless close. This is also a somewhat longer period of
stronger wind gusts, which won't really ease up until later
Friday afternoon.

Looking for another low pressure to pass by to our south this
weekend. A third low pressure may move across northern New
England early next week.

Once the rainfall ends from our mid week storm, not thinking
precipitation chances will be very high. There will at least be
some risk, but southern New England does not appear like we will
be very close to any of the aforementioned systems, other than
the passage of a cold front at times. Will need to get a better
handle on the amount of available humidity to fine-tune this
aspect of the forecast.

&&

.AVIATION /06Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:

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

Tonight...High Confidence.

VFR. SW winds at 10-15 knots. Winds around 2kft around 40-45
knots will create LLWS.

Wednesday and Wednesday Night...Moderate Confidence.

VFR with pockets of MVFR/IFR possible this morning esspically
west of ORH. South winds pick up and gust 20-30 knots today.
With winds aloft still around 40-45 knots, there could be some
light LLWS around much of the day. Wind shear picks up Wednesday
evening as a strong LLJ brings 2kft winds to 50-65 knots. Gusts
at the surface should stay elevated in the 20-30 knot range.
Rain moves in from west to east between 00z and 04z, but quickly
moves off shore by 12z Thursday. CIGS drop to IFR/LIFR with the
rain.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Thursday through Sunday/...

Thursday: MVFR/IFR conditions possible. Breezy. Chance SHRA.

Thursday Night: Mainly VFR, with local MVFR possible. Strong
winds with local gusts up to 40 kt.

Friday: VFR. Windy with gusts up to 35 kt.

Friday Night: VFR. Breezy. Slight chance RA, slight chance SN.

Saturday: VFR. Breezy. Slight chance RA.

Saturday Night: VFR. Breezy.

Sunday: VFR. Breezy. Slight chance RA, slight chance SN.

&&

.MARINE...
Forecaster Confidence Levels:

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

Tonight through Wednesday night...High

A modest southwest LLJ tonight will continue to result in Small
Craft Advisory wind gusts/seas persisting tonight into Wed
morning. As a very strong LLJ moves into the region later Wed
into Wed night, we expect southerly Gale force wind gusts to
develop despite an inversion. Gale Warnings remain posted for
all waters. Seas should build to between 7 and 13 feet across
the outer-waters. Rain and areas of fog will also impact the
waters late Wed and especially Wed night.

Outlook /Thursday through Sunday/...

Thursday: Low risk for Small Craft Advisory winds with local
gusts up to 30 kt. Rough seas up to 14 ft. Chance of rain
showers.

Thursday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Rough seas up to 12 ft. Slight chance
of rain showers.

Friday: Strong winds with gusts up to 30 kt. Rough seas up to
12 ft.

Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Slight chance of rain.

Saturday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Slight chance of rain.

Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Slight chance
of rain, slight chance of snow.

&&

.TIDES/COASTAL FLOODING...
A period of strong southerly wind gusts and modest pressure
falls will result in a 1.5 to 2.5 ft storm surge with a low risk
for up to 3 feet along the south coast. This may result in a
period of splashover or perhaps very minor coastal flooding
during the late Wed night astronomical high tide. Not expecting
any significant impacts, but it may warrant Coastal Flood
Statement/Advisory with later forecasts.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Gale Warning from 3 PM Wednesday to 7 AM EST Thursday for
     ANZ230>237-250-251-254>256.

&&

SYNOPSIS...Belk/Frank
NEAR TERM...Frank
SHORT TERM...Frank
LONG TERM...Belk
AVIATION...Belk/Frank/KP
MARINE...Belk/Frank
TIDES/COASTAL FLOODING...Frank