Area Forecast Discussion
Issued by NWS Boston, MA

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FXUS61 KBOX 251055
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
655 AM EDT Mon Mar 25 2024

.SYNOPSIS...
Cooler than normal temperatures are expected today and Tuesday along
with spot rain chance late tonight and Tuesday across for parts of
Rhode Island and eastern Massachusetts. Considerably milder
Wednesday with continued risk for showers. A frontal wave will
bring more widespread rain Thursday into early Friday then
drying in the afternoon. Dry and seasonable next weekend but
blustery on Saturday.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Highlights:

* Dry and cooler than normal temperatures expected.

* Minor river flooding continues across southeast Massachusetts and
  Rhode Island.

More or less a rinse and repeat forecast, similar conditions from
Sunday. Once again, we are situated between two pressure systems,
increasing the wind speeds. Do anticipate the more gusty winds, up
to 35 mph, are felt across southeast Massachusetts, Cape Cod, and
Islands through Monday afternoon. As for temperatures, the northeast
flow will keep 925mb temperatures fairly low, -4C to -6C, around
10th percentile, based off sounding climatology from CHH. Afternoon
highs reach the low and mid 40s, with parts of southwest Connecticut
where the winds are less breezy could reach the upper 40s - areas
south and west of Hartford.

Dry conditions continue to day, high cirrus clouds slowly thicken
late in the day from southeast to northwest due to surface low
pressure system moves north.

Forecast from the NERFC was issued last night at 10pm is the basis
for the current warnings; Taunton River at Bridgewater, Pawtuxet
River at Cranston, Pawcatuck River at Westerly, and Wood River at
Hope Valley. Two rivers we continue to watch for the potential to
reach minor flood stage are Pawcatuck River at Rood River Junction
for later this morning, though the forecast calls for the river
graze minor flood stage as it would crest - as a result have held
off on issuance of a new river flood warning. Did collab with the
NERFC and was told the forecast for Pawcatuck at Wood River Junction
had decreased throughout the Sunday. FWIW, the MMEFS has a 49
percent chance the river will reach minor flood stage -stay tuned!
Lastly, the Charles River at Dover may crest into minor flood by
Tuesday afternoon/late evening.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Highlights:

* Spotty showers overnight and into Tuesday for eastern
  Massachusetts and Rhode Island.

* Gusty northeast winds continues along with chilly temperatures by
  late March standards.

Tonight: Increasing clouds and ceilings lowering low chance of a
scattered rain shower predawn across the Islands and outer Cape Cod
as moisture from a distant ocean storm lifts north. Otherwise a
generally dry night. Low temperatures will vary depending on
location and amount of sky cover there is. Current thought are there
will be enough clouds over much of eastern Massachusetts and Rhode
Island to allow for a more mild night with lows between the upper
20s and mid 30s. Further west where there is less clouds and light
winds temperatures will be able to fall well into the low 20s and
upper teens.

Tuesday: Surface high pressure shifts northeast, but the flow still
remains onshore - yet another cool/raw day with high temperatures in
the upper 30s and low 40s. Wind remains out of the northeast 10 to
15 mph, gusting to 25 mph and coastal areas 15 to 20 mph, gusts to
35 mph. Little sunshine to be had with spotty showers possible
across eastern Massachusetts and Rhode Island, by no means is this a
washout, QPF amounts are generally a few hundredths of an inch east
of the I-95 corridor.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Highlights:

* Spotty light rain showers Tue night, then turning milder Wed but
  continued risk for showers

* More widespread rain developing Thu into early Fri, possibly heavy
  at times in eastern New Eng

* Dry and seasonable next weekend with gusty NW winds Sat.

Details:

Overall a pretty unsettled pattern through the end of the workweek,
with several chances of at least light showers and abundant cloud
cover. More widespread rainfall expected toward the end of the week
but details are still a bit uncertain.

Tuesday night and Wednesday:

Persistent NE flow and abundant low level moisture will keep low
clouds across SNE Tue night with spotty light rain at times,
especially eastern half SNE where deeper moisture is present.
Surface ridging extending south from the Maritimes favors a cold air
damming set up and temps may drop to near 32 across northern MA
higher elevation where localized light freezing rain/drizzle is
possible. The risk is low but something to monitor early this week.
Then on Wed, more of the same with chance of showers at times as a
frontal boundary approaches from the west and interacts with modest
moisture plume. Milder Wed as winds turn southerly with highs in
the 50s.

Wednesday night through Friday:

Surface front will cross SNE Wed night and likely stall to the east
on Thu as upper trough amplifies to the west. Favorable jet dynamics
with right entrance region of the jet acting on deep moisture plume
just to the east will result in widespread rain developing and
lifting northward across SNE late Wed night through Thu night. Where
the axis of rainfall sets up is still somewhat uncertain and will
depend on the location of the stalled front and deep moisture axis.
Will also have to consider the track of a southern stream frontal
wave which may enhance rainfall across SE New Eng as strong
shortwave lifts NE from the SE CONUS. Consensus of the deterministic
and ensemble guidance favor eastern New Eng for potential heavy
rainfall although there are subtle differences in the rainfall axis.
ECMWF ensembles are focused more across Cape/Islands while GEFS and
CMC ensembles have potential heavy rain impacting much of eastern
New Eng. Ensemble probs of greater than 1" are high (70-80%) within
the rainfall axis and the 90th percentile QPF values exceed 2
inches. A significant rainfall event is possible in eastern New Eng
and probabilistic hydrographs from the NAEFS and GEFS indicate
renewed flooding for RI rivers.

Bulk of the rain should begin to exit on Fri but timing is uncertain
and will depend on the track and timing of the frontal wave. Highest
PoPs Fri will be in the east.

Saturday and Sunday:

System deepens and moves into the Maritimes with drier NW flow which
should result in a mostly dry weekend, although NW winds will be
gusty on Sat. Seasonable temps.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

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

12z TAF Update:

Today... High Confidence.

VFR. Eastern terminals have NE wind 15 to 20 knots with gusts
to 30 knots. Western terminals have NE wind 10 to 15 knots and
gusts to 25 knots.

Tonight...High confidence.

MVFR cigs developing over Cape/Islands after midnight, then
overspreading eastern MA and RI by 12z.

Tuesday... High Confidence.

MVFR ceilings expanding west across rest of SNE. Isolated areas
of IFR after 18z. Low chance for an isolated light rain shower
for eastern terminals. Eastern terminals have NE wind 15 to 20
knots with gusts to 30 knots. Western terminals have NE wind 10
to 15 knots and gusts to 25 knots.

KBOS TAF...High confidence in TAF.

KBDL TAF...High confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night: MVFR/IFR conditions possible. Breezy. Chance RA,
chance FZRA.

Wednesday through Wednesday Night: Mainly VFR, with local IFR
possible. Chance RA.

Thursday: Mainly MVFR, with areas IFR possible. RA likely.

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

Friday: Mainly VFR, with local MVFR possible. Windy with gusts
up to 30 kt. Slight chance RA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Today: Low pressure system moves north and continues gusty NE gales
on the southern and eastern outer waters. Northeast waters gusts
near 30 knots. Seas on the outer waters are greater than 14 feet,
near shore waves are 6 to 10 feet.

Tonight: Low pressure to our south will continue to bring strong NE
winds 20-30 kts gusting to 40 kts. Seas on the outer waters 12 to 15
feet, near shore waves are 7 to 11 feet.

Tuesday: Low pressure system drifts south late in the day, gusty NE
gales continue first half of the day before diminishing. Seas on the
outer waters lower to 8 to 12 feet, while southern near shore waters
are 4 to 8 feet, eastern near shore waters are up to 10 feet.

Outlook /Tuesday Night through Friday/...

Tuesday Night: Winds less than 25 kt. Rough seas up to 12 ft.
Chance of rain.

Wednesday: Winds less than 25 kt. Areas of rough seas. Chance
of rain.

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

Thursday: Winds less than 25 kt. Seas up to 5 ft. Rain likely.

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

Friday: Moderate risk for Small Craft Advisory winds with local
gusts up to 30 kt. Rough seas up to 9 ft. Chance of rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 8 PM EDT Tuesday for ANZ230-231-236-
     237-250-251.
     Gale Warning until 2 PM EDT Tuesday for ANZ232>235-254>256.

&&

$$

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


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