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466
FXUS61 KBOX 171907
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
307 PM EDT Mon Mar 17 2025

.SYNOPSIS...
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A cold front and associated precipitation slowly edges east tonight
through Tuesday morning before a drier air mass works it`s way over
southern New England for Tuesday afternoon. Mainly dry and mild
weather returns Tuesday into Thursday. Another frontal system
will likely bring a period of showers sometime late Thursday
into Friday, possibly changing to snow over higher elevations
Friday as colder moves back into the region. Dry and seasonable
conditions follow next weekend.
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&&

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

* Clouds and showers persist through this evening before rain
  tapers off The Cape/Islands tomorrow morning

* Trending drier tomorrow with mild temperatures in the mid to
  upper 50s

Rest of Today and Tonight

Heaviest precipitation has ended for most of southern New England,
though there remains a batch of steady to moderate rainfall mainly
over The South Coast, Cape, and Islands. The leading edge of a
surface cold front is currently bisecting MA from north to south,
roughly through Worcester. Winds west of the front have shifted
northwest and we can expect the rest of the region to see winds
shift northwest as this boundary makes its way east this evening and
overnight. Ample moisture remains ahead of the frontal boundary with
PWATs around an inch or greater. While the strongest forcing
associated with this system has passed, we still have upper level
forcing for ascent with the presence of the right entrance region of
an upper-level jet overhead. This will continue to support periods
of spotty precipitation through this evening. Showers will gradually
taper off over night as the front works east and mid-level dry air
intrudes from the west. Expect most locations to be dry/clear by
sunrise tomorrow with the exception of The Cape/Islands where some
showers may linger. Low temps overnight in the mid to upper 30s.
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&&

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

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Tomorrow

Some lingering clouds tomorrow morning as showers and moisture
associated with an eastward moving cold front continue to shift
east. A mid-level ridge builds in behind the front with seasonable
925 hPa air slightly above 0 Celsius. With northwest flow and
diurnal mixing, this will translate to surface temperatures in the
mid to upper 50s tomorrow afternoon. Clouds may linger a bit longer
over The Cape/Islands which may suppress high temperatures to the
40s. Elsewhere across the interior, there should be a good bit of
sunshine, especially for mid-afternoon hours. Steady northwest winds
from 10 to 15 mph gradually become light out of the northeast by mid-
afternoon. Overall a fairly quiet day.

Tomorrow Night

Remaining cloud cover over The Cape/Islands completely clears out
tomorrow night. Light/variable winds should support efficient
radiational cooling that will allow temperatures to dip below
freezing for select locations in interior New England and eastern
MA. Elsewhere, temperatures in the mid to upper 30s will be common.
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&&

.LONG TERM /WEDNESDAY THROUGH MONDAY/...

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Key Messages:

* Warm and dry for Wednesday and much of Thursday

* Next round of rain likely Thursday night into Friday

* Windy Friday following frontal passage with slightly below normal
  temperatures that rebound over the weekend

Details...

Light northerly winds begin to shift to the east Wednesday morning,
likely bringing some lingering clouds to the area. The onshore flow
will help to mitigate Wednesday`s high temps for the Cape and
eastern shores while temps across the interior will most likely
reach at least 55F. Ensemble guidance is indicating 70 percent
probability or higher for the CT Valley reaching 60F. River rises
and possible minor flooding from the rain earlier in the week
combined with snowmelt from northern New England will continue to be
a concern along creeks and larger rivers. More details on that can
be found in the hydrology section of this discussion.

The next system will originate as a trough digging into the central
US Wednesday that moves northeast into the Great Lakes region on
Thursday. While the surface low will continue northeast into
southern Ontario, the cold front will extend down into the northeast
US by Thursday night. Guidance continues to hint at the development
of a secondary low along this front over the Mid-Atlantic region
that could track through southern New England. Winds ahead of this
system on Thursday will continue to shift from Wednesday easterly to
southeasterly, and they`ll begin to strengthen as the pressure
gradient tightens throughout Thursday. Dominant onshore flow will
once again ramp up PWATs to anomalously high values... ECMWF and GFS
ensembles still sitting around 0.6" to 0.7" across the region (about
200 percent of normal). The lift from the cold front combined with
this increased moisture will set the stage for more rain and a few
hours of flurries across southern New England starting sometime
Thursday night and continuing into Friday morning. The latest ECMWF
ensemble has 60 percent probs of seeing 1" or greater of snow in the
Berkshires, 30-40 percent in the Worcester Hills, and exceedingly
less likely elsewhere. ECMWF and GFS ensemble guidance are also
indicating 24-hour QPF amounts of less than 0.5", so the odds of any
snow sticking on the ground are quite low.

Cooler temperatures aloft along with post-frontal winds from the NW
will lead to dry, cool and breezy conditions Friday, keeping highs
in the 40s for most and dew points down in the 20s and teens. The
cold front moves offshore by Friday afternoon, leaving temperatures
around 5F below normal overnight. Lows will likely sit in the 30s
for much of the region, with higher elevations in the upper 20s.
Highs rebound into the mid 50s for Saturday as temperatures aloft
get above 0C at 850 mb (and up to +5C at 925 mb) with breezy W
winds. The ECMWF deterministic and ensemble guidance is hinting at a
shortwave approaching just to the south of the region or right over
it Sunday morning, which may bring some scattered showers depending
on how this wave tracks -- or if it develops at all. Otherwise,
light W winds prevail into Sunday morning, with the other ensembles
indicating more zonal flow.
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&&

.AVIATION /19Z MONDAY THROUGH SATURDAY/...
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Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18Z TAF Update
Through 00Z...High Confidence in trends. Moderate confidence in
timing.

Winds gradually shift to the northwest after 20-21Z. Light rain
lingers but gradually tapers off from west to east. Showers
linger a bit longer at BOS and Cape/Islands terminals. Remaining
IFR ceilings should lift to MVFR as winds shift northwest. Some
20 knot gusts possible after the wind shift.

Tonight...High Confidence in trends. Moderate confidence in
timing.

North/northwest winds from 10 to 20 knots. MVFR ceilings persist
for most of the evening but should improve back to VFR by 12Z as
a drier air mass works its way into the reigon.

Tuesday...High confidence.

VFR across the western half of southern New England. MVFR and
local IFR becoming VFR by early afternoon farther east.


Tuesday Night...High Confidence.


VFR. Light and variable winds.

KBOS TAF...Moderate confidence
in TAF.

KBDL TAF...Moderate Confidence in TAF.

Outlook /Wednesday through Saturday/...

Wednesday through Wednesday Night: VFR.

Thursday: Mainly VFR, with local MVFR possible. Breezy. Slight
chance RA.

Thursday Night: Mainly MVFR, with areas IFR possible. Breezy.
RA.

Friday: Mainly VFR, with local IFR possible. Windy with gusts
up to 30 kt. RA likely.

Friday Night: VFR. Breezy. Slight chance RA.

Saturday: VFR. Breezy.
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&&

.MARINE...
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Forecaster Confidence Levels:

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

Tonight

Cold front crosses the waters tonight. This will support winds
shifting to the north/northwest. Moderate winds over the coastal
waters expected with sustained speeds of 15 to 25 knots and gusts up
to 30 knots over the outer marine zones. Small Craft Advisories
remain in effect.

Tomorrow

Stronger/gusty northwest winds gradually diminish tomorrow morning
and eventually become more modest out of the north/northeast from 10
to 15 knots. Seas remain elevated enough to justify Small Craft
Advisories which remain in effect through 8PM tomorrow night.
`
Tomorrow Night

Northeast winds from 5 to 10 knots over the coastal waters. SCY
headlines may need to be extended with 5 foot seas over the outer
marine zones. Near-shores zones seas will be 4 feet or less.

Outlook /Wednesday through Saturday/...

Wednesday through Thursday: Winds less than 25 kt. Seas up to
5 ft.

Thursday Night: Winds less than 25 kt. Areas of rough seas.
Rain likely.

Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 25 kt. Rough seas up to 8 ft. Chance of rain.

Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Rough seas up to 9 ft. Slight chance of
rain.

Saturday: Winds less than 25 kt. Seas up to 5 ft.
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&&

.HYDROLOGY...
215 PM Update:

Heavy rains which occurred early Monday morning have started to
shift eastward to Cape Cod and the Islands, with rain intensities
across most of Southern New England lightening or tapering off
entirely. Much of RI and southeast MA saw the highest rainfall
totals with 1.5-2.5 inches of rain being common, and rain amounts of
about an inch or so in northern/northwestern MA and into CT.

In response to this rainfall, and with some additional ongoing
contributions from a combo of rain and snowmelt occurring
upriver along the Connecticut River basin, river flood warnings
are active on portions of the Connecticut River and on the Wood
River at Hope Valley.

For the Connecticut River...gradual river rises remain expected
on the entire reach of the Connecticut through at least Tuesday
as water from rain and snowmelt moves downriver. River Flood
Warnings are in effect for the Connecticut River at Montague,
Northhampton, Thompsonville, Hartford and Middle Haddam (in
southern Connecticut) with crests into the Minor flood stage.
Earliest onset of minor flood stage levels take place on the
Connecticut at Montague and Connecticut at Northhampton,
expected to rise late this afternoon and early tonight. Further
downriver at Thompsonville, Hartford and Middle Haddam, minor
flood stage is forecast to take place overnight into early on
Tuesday. Gradual recession in river levels below flood stage are
expected from north to south through Thursday, taking the
longest in the lower reaches of the Connecticut near Middle
Haddam as this gage is affected by tidal effects. See the latest
river flood warning text statements for anticipated flooding
impacts as well as river level forecasts from the Northeast
River Forecast Center.

For the Wood River at Hope Valley...the river will continue to
rise just above minor flood stage levels overnight tonight, then
recede below flood stage Tuesday morning. See the latest river
flood warning text statements for anticipated flooding impacts
and river level forecasts from the Northeast River Forecast
Center.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
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CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 2 PM EDT Tuesday for ANZ231>234.
     Small Craft Advisory until 8 PM EDT Tuesday for ANZ235-237-250.
     Small Craft Advisory until 6 AM EDT Wednesday for ANZ254>256.
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&&

$$

SYNOPSIS...McMinn/RM
NEAR TERM...RM
SHORT TERM...RM
LONG TERM...McMinn
AVIATION...McMinn/RM
MARINE...McMinn/RM
HYDROLOGY...Loconto