812
FXUS61 KBOX 031851
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
151 PM EST Tue Mar 3 2026

.WHAT HAS CHANGED...
No significant changes made to the wintry mix today and
tonight...but some black ice is a concern after this activity
departs for the early Wednesday morning commute.

&&

.KEY MESSAGES...

- Mainly snow arrives from southwest to northeast between 11 am
  and 3 pm then changes to rain near the coast but with pockets
  of light freezing rain across the interior into tonight. Snow
  accumulations a coating to 2" with ice accretion up 0.10".

- Areas of black ice possible early Wed morning. Otherwise...dry
  & milder Wed with highs in the upper 40s to the middle 50s.
  The one caveat is if fog hangs on later than expected...highs
  will be cooler than currently forecast.

- A period of wintry precip remains possible Thu night into  early
Fri.

- Pattern change towards milder weather this weekend and
  potentially warmer next week.

&&

.DISCUSSION...
KEY MESSAGE 1...Mainly snow arrives from southwest to northeast
between 11 am and 3 pm then changes to rain near the coast but with
pockets of light freezing rain across the interior into tonight.
Snow accumulation`s a coating to 2" with ice accretion up
0.10".

A large 1040 mb high pressure system will continue to shift further
east and way from the region today. At the same time...shortwave
energy will approach from the west so brief morning sunshine will
quickly fade by lowering and thickening clouds. This shortwave will
also induce a modest southwest LLJ on the order of 35 to 45 knots.
This will increase the forcing for ascent and precipitation should
arrive from southwest to northeast...roughly between 11 am and 3 pm.
Thermal profiles indicate antecedent airmass should initially be
cold enough for mainly snow except perhaps the immediate south
coast, Cape and Islands. Given light to moderate intensity during
the daylight hours...the early March sun angle will probably keep
roads wet/slushy outside the highest terrain. Snow  of a
coating to 2 inches of snow with higher amounts expected north
of I-90.

High pressure sliding directly east of our latitude...mid level
warmth will quickly overspread the region. This will allow snow
to change to rain along the coastal plain from south to north
with perhaps a brief period of sleet during the
transition...roughly in the 4 to 8 pm time frame. Periods of
rain & drizzle will continue tonight across the coastal plain
along with areas of fog. The bigger concern will be northwest of
I-95 and into parts of the interior where temps will remain at
or below freezing into Tue night. This will result in the snow
transitioning to pockets of light freezing rain. Ice accretion
of up to one tenth of an inch are possible and untreated
roads/walkways may become icy tonight.

Departing shortwave should bring an end to the precipitation toward
daybreak. Light winds and perhaps some clearing may result in areas
of fog and black ice for the Wed morning commute.

KEY MESSAGE 2...Areas of black ice possible early Wed morning.
Otherwise...dry & milder Wed with highs in the upper 40s to the
middle 50s. The one caveat is if fog hangs on later than
expected...highs will be cooler than currently forecast.

Give the left over low level moisture, light winds, and near or sub-
freezing temperatures will have to watch for areas of fog and black
ice early Wed morning. Otherwise...subsidence behind tonight/s
shortwave should allow plenty of sunshine and 925T remain
between +5C and +6C. This should yield a mild Wednesday
afternoon with highs in the upper 40s to the middle 50s. Most
locations away from the immediate coast/sea breeze potential
should break 50! The one caveat is the potential for low
clouds/fog patches to hang on later than expected. Given very
weak surface flow this can not be ruled out...so if this were to
occur highs would be lower than currently forecast.

KEY MESSAGE 3...A period of wintry precip remains possible Thu night
into  early Fri.

Mid to late week the synoptic pattern remains flat and zonal with
the first shortwave moving through late Thursday into Friday. This,
while a 1040mb high pressure sits over southeast QC setting up a
potential cold air damming situation. While the mid level
disturbance moves through a moist environment on Thursday bringing
rain to much of the area, stubborn NE surface flow into the high
terrain will likely keep temps below freezing leading to the
possibility of freezing rain. The risk for now looks to be limited
to the high terrain of interior MA and CT where ensemble guidance
paints a 20-35% chance of at least a tenth of an inch of ice
overnight.

KEY MESSAGE 4...Pattern change towards milder weather this weekend
and potentially warmer next week.

There continues to be good model agreement in a pattern shift
looking into the extended forecast with an Atlantic ridge leading to
warmer SW flow directed into southern New England. However, there
remains a good degree of uncertainty as to the magnitude and
duration of the warm up given the quick, transient pattern; GEFS
plumes show a big increase in spread in 2M-Temp guidance beyond
Friday highlighting that lower confidence. Overall, though, high
temperatures in the low 50s are possible this weekend with perhaps
even some low 60s as we go into the new week. This with a high March
sun angle and elevated dewpoints will help to melt away our existing
snowpack.

&&

.AVIATION /18Z TUESDAY THROUGH SUNDAY/...
Forecaster Confidence Levels...

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

18z TAF Update...

Today...High confidence in trends with moderate confidence in
timing/ptypes.

MVFR-IFR conditions. Ptype initially mainly snow to start this
afternoon for most. Change to rain from south to north occurs
in the 20z to 01z timeframe along the coastal plain with a period
of sleet during the transition. Low chance for brief period of
freezing rain before a change over to rain. Snow/sleet
transitioning to pockets of light freezing rain by early evening
for interior terminals.

Tonight...High confidence in trends. Moderate for exact ptype.

IFR to LIFR conditions expected tonight with periods of rain
along the coastal plain and pockets of light freezing rain
across parts of the interior. Winds generally less than 10 knots
today and tonight becoming WNW Wednesday morning.

Wednesday...Moderate confidence (timing of improvement to VFR)

IFR improving to VFR early Wednesday morning. Lingering low
clouds/fog possible early AM. Lower confidence is exact timing
of improvements to VFR. Ceilings should improve to VFR 11-16Z.
NW winds 5-10 kts.

KBOS Terminal...Moderate confidence (ptype today/tonight and
VFR timing Wed).

Snow to start with a wintry mix/sleet possible after 22Z.
Flipping to rain by 00z. Low risk for a brief period of freezing
rain before changing over to rain. Rain exits by 12Z. Slushy
coating of snow on runways. Visibilities bouncing between 2SM
to as low as a 1/2SM worst case this evening/tonight. Moderate
confidence in exact timing of improvements to VFR early
Wednesday AM, but more likely between 10-13Z.

KBDL Terminal...Moderate confidence in TAF.

Snow flips to light rain/freezing rain 20-22z with perhaps a
period of sleet during the transition. Temps this evening will
be near freezing...so impacts may be somewhat limited on runways
but some icing can not be ruled out. Rain exits by 10Z
Wednesday. Lower confidence with timing of improvements to VFR,
but generally are expected to improve 13-16Z. Low stratus and
BR/FG may linger early Wednesday morning with ceilings
potentially not improving until late AM (worst case).


Outlook /Wednesday through Sunday/...

Wednesday: Mainly VFR, with local MVFR possible. Patchy BR.

Wednesday Night: Mainly VFR, with local IFR possible. Patchy
FG.

Thursday: Mainly VFR, with local IFR possible. Chance RA,
slight chance FZRA.

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

Friday: MVFR/IFR conditions possible. Breezy. RA likely, chance
FZRA.

Friday Night: Mainly VFR, with areas IFR possible. Slight
chance RA, slight chance FZRA.

Saturday: Mainly VFR, with local IFR possible. Breezy. Slight
chance RA.

Saturday Night: Mainly VFR, with local IFR possible. Breezy.
Chance RA.

Sunday: VFR. Slight chance RA.

&&

.MARINE...
Forecaster Confidence Levels...

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

Today through Wednesday...High confidence.

High pressure continues to move east of the waters today. This will
result in long S-SW fetch and build seas into the 3 to 6 foot range
late tonight into Wed across our southern waters. Therefore...we
have issued small craft advisories for our southern outer-
waters.

Outlook /Wednesday through Sunday/...

Wednesday: Winds less than 25 kt. Seas up to 5 ft. Patchy fog.
Local visibility 1 to 3 nm.

Wednesday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Patchy fog. Local visibility 1 nm or less.

Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain. Local visibility 1 nm or less.

Thursday Night: Winds less than 25 kt. Areas of seas
approaching 5 ft. Rain likely.

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

Friday Night through Saturday: Winds less than 25 kt. Areas of
rough seas. Slight chance of rain.

Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Areas of rough seas. Chance of rain.

Sunday: Winds less than 25 kt. Seas up to 5 ft. Chance of rain.

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Weather Advisory until 7 AM EST Wednesday for
     CTZ002>004.
MA...Winter Weather Advisory until 7 AM EST Wednesday for
     MAZ002>012-014-026.
RI...Winter Weather Advisory until 7 AM EST Wednesday for RIZ001.
MARINE...Small Craft Advisory from 10 PM this evening to 7 PM EST
     Wednesday for ANZ254>256.

&&

$$

DISCUSSION...Frank/BW/Nocera
AVIATION...Loconto/Hrencecin/Mensch
MARINE...Frank/BW/Nocera