BOX issues Area Forecast Discussion (AFD) at Feb 26, 3:15 AM EST684
FXUS61 KBOX 260815
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
315 AM EST Wed Feb 26 2025
.SYNOPSIS...
Dry, blustery and mild today then a frontal system will bring a
period of rain and snow late tonight before changing to all
rain Thursday. Blustery and somewhat cooler weather returns
Friday, then a clipper system will bring more snow to northern
MA late Friday night before changing to rain showers Saturday.
Behind this system, blustery and cold conditions follow for
Sunday and Monday with below normal temperatures. Milder air
returns next Tuesday.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Upper level trough axis moves to the east today with weak
shortwave ridging providing subsidence. The subsidence and dry
airmass will result in mostly sunny skies today mixed with some
strato-cu, with high clouds increasing later in the afternoon
ahead of the next system. It will become breezy today as
soundings show a well mixed boundary layer supporting NW gusts
to 20-30 mph at times. Cooler post-frontal airmass today with
925 mb temps around 0C will lead to highs mid-upper 40s, except
around 50 in the coastal plain.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM THURSDAY/...
Key Messages:
* A period of snow late tonight with minor accums north of the MA
Pike. Mainly rain, possibly mixed with snow south of the Pike.
Minor impacts to Thu morning commute across the higher elevations
in northern MA
* Snow in far northern MA changes to rain Thu morning with a brief
period of freezing rain possible during the transition across
higher elevations
Tonight and Thursday...
Upper level trough amplifies across the Gt Lakes tonight into Thu
with a series of shortwaves rotating into New Eng. Surface low pres
moves NE from the Ohio valley and tracks to the north on Thu. Decent
low level jet 50-60 kt will bring a plume of higher PWATs into SNE
and increase forcing for ascent at the nose of the jet. Precip
overspreads SNE after midnight tonight and continues into Thu. The
column is cold enough for precip to begin as snow especially north
of the MA Pike, and there could even be a brief period of snow
across northern CT and northern RI otherwise mostly rain here.
Milder air aloft will gradually lift northward across northern MA
late tonight into Thu morning with snow transitioning to rain. One
thing we will have to watch is the potential for a brief period of
freezing rain Thu morning over the Berkshires and Worcester Hills
during the precip transition. Can't rule out a brief period of ice
but confidence is low as soundings suggest more of a snow to rain
scenario given near isothermal temp profile near zero below 850 mb
as the column is warming. Will have to examine this further with
later forecasts.
Regarding potential snow accums before the changeover to rain, we
are expecting a coating to an inch north of the MA Pike, but 1-3
inches possible over the Berkshires and Worcester Hills north of
Route 2. Minor impacts to the morning commute expected in northern
MA, especially over the higher elevations.
Steadiest precip will be late tonight into Thu morning, especially
interior, then rain will become more scattered into the afternoon as
the warm front lifts northward and the low level jet moves to the
east. Dry slot moves in from the west late in the day.
Temps will rise through the 40s Thu afternoon with some lower 50s
possible in RI and SE MA. Colder air may hang on north of Route 2
into the Berkshires with temps struggling into the lower 40s. 925 mb
jet around 60 kt moves up across the Cape/Islands later Thu morning
and early afternoon but soundings show a strong low level inversion
in place which will prevent these winds from mixing down to the
surface. But gusts to 35 mph will be possible.
&&
.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
Key Messages:
* Dry with gusty northwest winds on Friday
* Another round of snow changing to rain expected Friday night
into Saturday morning
* Cold and blustery conditions settle in behind a cold front
Saturday night, and continue into early next week
Latest guidance suite in rather good agreement with the overall
synoptic picture. Still some timing and intensity differences
that will need to get resolved over the coming days. That said,
have above average confidence in the overall theme for this
portion of the forecast.
The first order of business is the departure of a low pressure
moving east across northern New England Thursday night.
Expecting rainfall to end from west to east Thursday night,
especially after midnight.
Modest cold air advection and plenty of sunshine should result
in another gusty day Friday. Peak wind gusts will depend on
the strength of the low-level jet which is uncertain at this
time range, but ensemble means are suggesting wind speeds
between 25 and 40 knots in the 925 hPa to 850 hPa layer. This is
consistent with surface gusts in the 30-35 mph range with an
expected well mixed boundary layer Friday afternoon.
Another low pressure should pass over northern New England
Saturday. Have greater confidence in showers across northern
MA that towards the south coast. A subtle change in track could
have a big impact on what should be mostly a rain event, with
the possibility of some light snowfall towards the end sometime
Saturday afternoon into Saturday night.
High pressure then expected to return drier and colder
conditions Sunday into Monday. Still dry but likely warmer
Tuesday.
Anticipating temperatures to not be as much above normal Friday,
before a brief surge of warmth Saturday. A large high pressure
moving southeast from central Canada trends temperatures below
normal Sunday into Monday. Thinking it will be a little warmer
Tuesday as this high pressure moves offshore.
&&
.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Today...High Confidence.
VFR for most. Areas of MVFR towards the Berkshires this morning.
WNW/NW winds 5-12 kts, with gusts up to 25 kts developing after
14z.
Tonight...High Confidence
VFR with light/variable winds through 06Z. MVFR ceilings
overspread the region from west to east between 06Z and 12Z
with some -SN/-RA.
Thursday...High Confidence.
Mix of conditions. IFR for most to start the day, then becoming
MVFR during the morning with lingering IFR across the higher
terrain. Mainly MVFR with local VFR during the afternoon hours.
Any -SN should quickly change to -RA by 13-15Z.
KBOS TAF...High confidence in TAF.
KBDL TAF...High confidence in TAF.
Outlook /Thursday Night through Sunday/...
Thursday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance RA.
Friday: VFR. Breezy.
Friday Night: Mainly VFR, with local MVFR possible. Breezy.
Slight chance SN.
Saturday: Mainly VFR, with local MVFR possible. Breezy. Chance
RA.
Saturday Night: VFR. Breezy. Slight chance SN.
Sunday: VFR. Breezy.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today...High Confidence.
Gusty NW winds to 25 kt developing this morning, strongest across
eastern MA waters where SCA in effect. Winds begin to drop off late
today.
Tonight and Thursday...High confidence.
Winds diminish this evening and become southerly late tonight,
then increase to 20-30 kt Thu as low level jet moves across the
waters. Seas build to 6-9 ft over the outer waters Thu. Periods
of rain late tonight into Thu with vsbys reduced at times.
Outlook /Thursday Night through Sunday/...
Thursday Night: Winds less than 25 kt. Rough seas up to 9 ft.
Chance of rain.
Friday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas.
Friday Night: Winds less than 25 kt. Local rough seas. Slight
chance of snow.
Saturday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Chance of rain.
Saturday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Slight chance of rain,
slight chance of snow.
Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of
freezing spray, slight chance of snow.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 4 PM EST this afternoon for ANZ231-
250-251-254.
Small Craft Advisory from 7 AM Thursday to 1 AM EST Friday for
ANZ232>235-237-255-256.
&&
$$
SYNOPSIS...Belk/KJC
NEAR TERM...KJC
SHORT TERM...KJC
LONG TERM...Belk
AVIATION...Belk/KJC
MARINE...Belk/KJC
Source:
BOX issues Area Forecast Discussion (AFD) at Feb 26, 3:15 AM EST----------------
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