978
FXUS61 KBOX 291018
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
618 AM EDT Tue Apr 29 2025
.SYNOPSIS...
Plenty of sunshine and becoming quite breezy and unseasonably warm
today with highs in the upper 70s to 80+ away from the south
coast. A cold front crosses the region tonight...but nothing
more than brief scattered showers are possible across parts of
interior southern New England as the activity rapidly weakens as
it moves east. Dry weather with pleasant temperatures is on tap
for Wednesday and Thursday. Next chance for showers arrives
early Friday with a few rounds of showers possible Friday and
another round of rain for Saturday. Temperatures trend slightly
above normal. Cold front moves in late Saturday bringing cooler
temperatures for Sunday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages...
* Sunshine today & becoming quite breezy with wind gusts of 25-35 mph
* Highs today upper 70s to 80+ away from the south coast
Details...
High pressure will continue to move east and away from the mid-
Atlantic coast today. At the same time...a cold front will be
dropping south into northern New England. The increasing gradient
will allow for a modest southwest LLJ of 40-50+ knots to develop
during the afternoon and especially by early evening. This will
result in southwest wind gusts increasing to between 25 and 35 mph
with perhaps a few brief gusts near 40 mph. 925T will rise to
between +15C to +17C should allow for an unseasonably warm
afternoon. Highs should top out in the upper 70s to 80+ away
from the south with plenty of sunshine and just some thin high
clouds at times. The gusty SW winds off the ocean will result in
cooler high temps in the 60s to near 70 near the immediate
south coast.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM WEDNESDAY/...
Key Messages...
* Brief scattered showers possible across interior southern new
England tonight but uncertain how far east activity survives
* Otherwise...quite breezy and unseasonably mild for much of tonight
ahead of the approaching cold front
* Sunny & breezy Wed with highs mainly in the middle 60s to lower 70s
Details...
Tonight...
The southwest LLJ will persist tonight ahead of the approaching cold
front...so it will remain quite breezy. This cold front will be
associated with showers and thunderstorms with severe weather likely
across upstate NY and parts of PA. However...mid level ridging in
southern New England coupled with diminishing diurnal instability
will result in the activity weakening significantly as it pushes
southeast towards our region. The guidance differs on how well the
activity holds together with the HRRR being the most aggressive in
allowing showers to impact much of the region. The other guidance is
not quite sold on that with the activity weakening faster.
Overall...thinking we may see a brief round of scattered showers in
parts of interior southern New England with the greatest risk in
northwest MA where a brief downpour or two is possible. Activity
will continue to rapidly weaken as it moves southeast with nothing
more than perhaps a brief sprinkle or two probably survives onto the
Boston to Providence corridor if even that. Later shifts may need to
make adjustments on the POPS...especially if it appears the more
aggressive HRRR starts to get support from other guidance later
today.
It will remain unseasonably mild tonight with temps only dropping
into the 60s this evening away from the south coast. Most locations
will see temps down into the 50s by daybreak Wed as NW winds usher
in somewhat cooler air behind the cold front.
Wednesday...
A very pleasant post-frontal airmass will be ushered into the region
on Wed. Plenty of sunshine and a bit of a northwest breeze
especially during the first part of the day. While we will see cool
advection working in aloft...the mild start coupled with the strong
late April sun angle will result in highs mainly in the middle 60s
to the lower 70s with the coolest of those readings mainly in the
high terrain.
&&
.LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/...
Key Messages:
* Dry and seasonable temperatures for Thursday.
* Slightly above normal temperatures Friday and Saturday. Chance for
showers Friday and another round of rain for Saturday.
* Dry with seasonable temperatures Sunday.
Details...
Wednesday Night through Thursday:
An upper level ridge begins to build in Wednesday night, setting up
Thursday to be another dry and pleasant day. A surface high
positioned to the east will support light wind patterns with light
northerly flow turning southerly for Thursday afternoon.
Temperatures will be more seasonable Thursday with highs in the 60s
for most spots and upper 50s/low 60s for the immediate coast, Cape,
and Islands.
Friday through Sunday:
Pattern becomes more unsettled by early Friday, with ensembles
indicating almost 200 percent PWAT anomalies across southern New
England ahead of a slow moving upper level trough. Ensemble guidance
shows a weak shortwave trough moving through Friday, followed by
another wave moving through sometime Saturday. This will bring a few
rounds of showers late Thursday night through Friday. Temperatures
for Friday look to be above normal with guidance suggesting mid to
high 70s for the interior and 60s for the Cape/Islands.
Saturday is going to be a little tricky, as timing on the next wave
is still quite uncertain. However... confident there`ll be another
round of rainfall Saturday. Expect breezy SW to W winds during the
day Saturday with gusts 20-25 mph. Temperatures lean above normal in
the mid 60s to low 70s. Conditions gradually dry out Saturday night
with a cold frontal passage.
Sunday trends drier with breezy northwest winds as a the main axis
of the upper trough slides across southern New England. Cooler
airmass behind the front will support highs around normal in the
60s. Residual moisture may support a few spot showers around during
the day.
&&
.AVIATION /10Z TUESDAY THROUGH SATURDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12z TAF Update...
Today...High Confidence.
VFR with SW wind gusts of 25 to 35 knots developing by mid
afternoon.
Tonight...High Confidence.
VFR conditions dominate...but a cold front may bring weakening
brief scattered showers into interior southern New England
tonight. Greatest risk for a few downpours will be in northwest
MA with nothing more than perhaps a sprinkle or two reaching the
I-95 corridor. SW wind gusts of 20 to 30 knots with a few gusts
near 35 knots possible towards the Cape. LLWS will also develop
too and are included in many of the TAFS.
Wednesday...High Confidence.
VFR. NW wind gusts of 20 to 25 knots with the strongest of the
winds through mid-afternoon.
KBOS TAF...High Confidence in TAF.
KBDL TAF...High Confidence in TAF.
Outlook /Wednesday Night through Saturday/...
Wednesday Night through Thursday: VFR.
Thursday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SHRA.
Friday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA, isolated TSRA.
Friday Night: Mainly VFR, with local MVFR possible. Breezy.
Chance SHRA.
Saturday: Mainly MVFR, with areas VFR possible. SHRA likely.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today and tonight...High Confidence.
High pressure moves off the mid-Atlantic coast as a cold front
approaches from the northwest later today and tonight. The result
will be a modest LLJ allowing for SW wind gusts of 25 to 35 knots to
develop this afternoon and persist into tonight. We went with strong
small craft advisories for most waters...but did go with Gale
Warnings for Buzzards Bay/MVY sound and Cape Cod Bay where where
excellent mixing nearshore should allow for 35 knot wind gusts at
times. Seas will become quite choppy this afternoon and continue
into tonight.
Wednesday...High Confidence.
Winds shift to the NW by daybreak Wed behind the cold front. We may
have some marginal morning small craft northwest wind gusts near
shore across eastern MA. While these winds should diminish some
during the afternoon...lingering swell will result in the need for
continuation of small craft advisories for seas across our southern
waters.
Outlook /Wednesday Night through Saturday/...
Wednesday Night: Winds less than 25 kt. Seas locally
approaching 5 ft.
Thursday: Winds less than 25 kt.
Thursday Night: Winds less than 25 kt. Slight chance of rain
showers.
Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas up to 5 ft. Slight chance of rain showers.
Friday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Chance of rain showers,
isolated thunderstorms.
Saturday: Winds less than 25 kt. Areas of seas approaching
5 ft. Rain showers likely.
&&
.FIRE WEATHER...
After collaboration with our surrounding WFO/s and Fire Weather
Partners...an SPS remains in effect today for the potential of
elevated Fire Spread. This is for the combination of minimum
afternoon relative humidity values dropping to between 25 and 35
percent with SW wind gusts on the order of 25 to 35 mph later today.
As for Wednesday...winds will not be quite as strong but some NW 25+
mph wind gusts will be possible especially during the first part of
the day. Minimum relative humidity values will be lower on the order
of 15 to 30 percent with drier NW flow behind the cold front. We
will be reaching out to the Fire Weather partners for the potential
of additional statements.
&&
.TIDES/COASTAL FLOODING...
Despite very quiet weather...King tides will result in the potential
for splashover or very minor coastal flooding again during the early
Wednesday morning high tide along parts of the eastern MA coast. The
MLLW Astro tide at BOS is 12.0 feet shortly before 130 AM Wed
morning. We may need another coastal flood statement for some minor
splashover...but really not looking at any real impacts especially
given the time of occurrence.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory from 2 PM this afternoon to noon EDT
Wednesday for ANZ230-232-235-237-251.
Gale Warning from 2 PM this afternoon to 2 AM EDT Wednesday
for ANZ231-233-234.
Small Craft Advisory from 2 PM this afternoon to 8 AM EDT
Wednesday for ANZ236.
Small Craft Advisory from 11 AM this morning to 8 AM EDT
Wednesday for ANZ250.
Small Craft Advisory from 11 AM this morning to 4 PM EDT
Wednesday for ANZ254>256.
&&
$$
SYNOPSIS...Frank/McMinn
NEAR TERM...Frank
SHORT TERM...Frank
LONG TERM...McMinn
AVIATION...Frank/McMinn
MARINE...Frank/McMinn
FIRE WEATHER...Frank
TIDES/COASTAL FLOODING...Frank
