169
FXUS61 KBOX 022338
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
738 PM EDT Wed Apr 2 2025

.SYNOPSIS...
An approaching warm front will bring a period of light rain tonight
into Thursday morning, with pockets of mixed wintry precipitation
possible across northern MA tonight. Milder conditions arrive
Thursday into Friday, with a stalled front possibly bringing a few
showers near the south coast Thursday night into early Friday.
Unsettled conditions continue this weekend, as a frontal system
impacts the region, with cooler temperatures Saturday followed by
milder conditions Sunday. Saturday appears to be the wetter of the
two days. Drying out Monday, as the frontal system exits the region,
along with cooler than normal temperatures overspreading the area
much of next week.

&&

.NEAR TERM /UNTIL 6 AM THURSDAY MORNING/...

740 PM update...

Forecast remains on track. WAA precip overspreading the region
from the west. Airmass is initially dry, so leading edge of
precip shield is partially evaporating before reaching the
ground. This is also resulting in evaporative cooling thru the
column, yielding some ice pellets mixing in with the rain at
KALB. Although, with surface temp there at 43F, no impacts.
Eventually, mid level warm nose climbs to +6C, too warm to
support sleet. Thus, all rain overnight, with the only exception
across the high elevations of western/central MA, where temps
may lower to near freezing, supporting some spotty freezing rain
at elevations above 1,000 ft. This remains a low prob, thus no
changes to the forecast. Farther south across CT/RI and SE MA,
less rainfall expected with best WAA farther northward. Earlier
discussion below.

-------------------------------------------------------------------

Key Messages:

* Periods of rain developing tonight

* Pockets of mixed wintry precip across the interior with
  spotty freezing rain possible over the higher elevations. Any
  travel impacts will be limited.

Higher clouds were already starting to arrive ahead of an
approaching warm front, While the surface part of this front
will probably not reach southern New England by daybreak
Thursday, there will be plenty of warm air higher up. Most model
soundings had peak warm nose temperatures of 4-6C. These
soundings also showed a 4-6km deep layer of colder air beneath
that warm nose. Overall, this should result in a period of
sleet between about 8 PM to 1 AM before transitioning to all
rain the rest of the night. Rainfall amounts for most
anticipated to be between 0.10-0.50 inches.

The other possibility is freezing rain. We had plenty of
sunshine today, which should mean surface, not the standard air,
temperatures well above freezing. The areas which would support
this precipitation type should be isolated. With limited impact
of icing this time of year, opted to not issue Winter Weather
Advisories for either the freezing rain or sleet. The main
areas of concern will be the higher terrain of the Worcester
Hills and towards the Berkshires.

&&

.SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY/...

Key Messages:

* Milder Thu with rain becoming more spotty in the afternoon

The approaching warm front should finally move to our north
during the day Thursday. This will lead to well above normal
temperatures. Any precipitation should be in the form of rain.
Once our region gets into the warm sector, then the rainfall
chances become more spotty by late morning into the afternoon.
A weak cold front should then try to pass through Thursday
night.

One forecast concern is temperatures, and the corresponding
impact on winds. Should more sunshine develop than currently
forecast, we likely get deeper boundary layer mixing. With a
40-50 kt low level jet at 925 mb, that could lead to stronger
winds than currently forecast, which is closer to the 90th
percentile of the NationalBlend guidance but still below Wind
Advisory thresholds. Forecast high temperatures in the 60s away
from the immediate coasts could reach the 70s in a few spots.

Drying out from north to south behind the aforementioned weak
cold front.

&&

.LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/...

Updated 2:50 PM

Key Messages

* Pleasant early spring day Friday afternoon

* Cooler on Saturday followed by increasing shower chances Saturday
  afternoon & night, then warmer and not as wet Sunday

* Trending drier, but cooler next week

Friday...

Wavy frontal boundary impacts the region Fri/Sat and Sun, with a
roller coaster ride in temps, along with wet and dry periods of
weather. The frontal boundary is south of New England Fri, but close
enough for moisture and associated showers to possibly clip the
south coast Fri morning. Then in the afternoon, northern stream s/wv
trough dives southeast from Quebec into Maine and then the
Maritimes, shifting the frontal boundary and its moisture farther
offshore and south of New England. Thus, dry weather for the
afternoon, along with increasing sunshine from north to south.
Modest NW winds 10-15 mph will combine with a well mixed boundary
layer to support highs in the low to mid 60s, about 10 degs warmer
than normal for early April. Looks like a real nice afternoon,
enjoy!

The Weekend...

The frontal boundary south of New England begins to return northward
as a warm front Saturday. Thus, dry weather Sat morning will be
replaced be increasing shower chances in the afternoon and night.
Looks pretty wet/widespread showers Sat aftn/night, with ensemble
probs of rainfall exceeding 0.10 inches at 100%. As for temps, much
cooler Saturday with 1030+ mb high over the maritimes, providing
cool air damming across SNE. This is evident as 925 mb temps dip to
0C to +2C across the area Sat. Therefore, 60s on Friday will be
replaced by temps in the 40s Sat, feeling even cooler along the
coast, with east winds 10-15 mph off the chilly ocean (SST 36-42F).

Warm sector overspreads the region Sunday, however, not a clean warm
sector airmass, with cold front quickly approaching from the west.
Thus, not sure how much if any breaks of sunshine we will see
Sunday, but warm sector airmass will provide dew pts in the 50s and
highs 60-65. So definitely a warmer feel to the airmass than Sat.
Bit of bust potential regarding temps Sun, +12C +16C at 925 mb
Sunday afternoon. If more sunshine and mixing materializes, some
locations away from the south coast could briefly pop into the 70s.
Ensembles hint at this, with low probs of 70+ highs. As for precip,
not a washout Sunday and definitely not as wet as Sat, but can`t
rule out a few showers Sun along and ahead of frontal boundary.
Given dew pts will be in the 50s, some SB instability combined with
frontal scale forcing may support a low risk of thunder.

Monday/Tuesday/Wednesday...

Monday looks to be a transition day, with frontal boundary moving
offshore and replaced by post frontal airmass. Thus, risk of early
morning showers, especially over southeast MA, but trending drier in
the afternoon. Seasonable temps, with highs in the 50s.

Tuesday and Wednesday, ensembles in good agreement on a fairly high
amplitude long wave trough carving out over Quebec and New England.
This will support mainly dry weather (other than an isolated PM
rain/snow shower with cold cyclonic flow aloft), but cooler than
normal, with highs 45-50.

&&

.AVIATION /00Z THURSDAY THROUGH MONDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

00z update...no change from previous TAFs.

Tonight...Moderate Confidence, mainly due to timing.

VFR trending to MVFR overnight. Local IFR across the higher
terrain late. Mostly -SHRA, but risk for -PL across the
interior with pockets of -FZRA higher elevations.

Thursday...Moderate Confidence.

Mainly IFR/MVFR with -SHRA in the morning becoming more spotty
in the afternoon. Increasing SW winds with gusts to 25-35 kt
developing.

Thursday Night...Moderate Confidence.

IFR/MVFR improving to VFR from NW to SE with passage of a cold
front.

BOS TAF...High confidence in trends. Moderate confidence in
timing. Risk for a spotty shower 03/01-05Z. Even lower risk for
light PL during that time. Not enough confidence to include it
in the TAF at this time, as it is more to not occur.

BDL TAF...High confidence in trends. Moderate confidence in
timing.

Outlook /Friday Night through Monday/...

Friday Night: VFR.

Saturday: Mainly MVFR, with local IFR possible. SHRA.

Saturday Night: MVFR/IFR conditions possible. Breezy. SHRA.

Sunday: Mainly VFR, with local IFR possible. Breezy. Chance
SHRA.

Sunday Night: Mainly MVFR, with local IFR possible. Breezy.
SHRA likely.

Monday: MVFR/IFR conditions possible. Breezy. Chance SHRA.

&&

.MARINE...
Forecaster Confidence Levels:

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

Winds and seas briefly diminish late this afternoon and early
evening. Increasing SE winds then develop overnight, building
seas once more. Considered gale force gusts during Thursday, but
have more confidence in strong Small Craft Advisory conditions.
Staggered the timing through tonight into Thursday. Winds should
diminish closer to sunset, but rough seas likely to linger
across the outer coastal waters.

Greater risk for reduced visibility in showers and fog across
the waters east of MA than the southern waters. A warm front
should move past the waters Thursday, with a cold front passing
the waters late Thursday night.

Outlook /Friday Night through Monday/...

Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft.

Saturday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain showers.

Saturday Night: Winds less than 25 kt. Seas up to 5 ft. Rain
showers.

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

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

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

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Small Craft Advisory from 10 AM to 10 PM EDT Thursday for
     MAZ020-021.
RI...None.
MARINE...Small Craft Advisory from 10 AM to 7 PM EDT Thursday for
     ANZ230.
     Small Craft Advisory from 7 AM to 10 PM EDT Thursday for
     ANZ231.
     Small Craft Advisory from 7 AM Thursday to 1 AM EDT Friday for
     ANZ232-234.
     Small Craft Advisory from 7 AM Thursday to 7 AM EDT Friday for
     ANZ233.
     Small Craft Advisory from 2 AM Thursday to 7 AM EDT Friday for
     ANZ235-237-255.
     Small Craft Advisory from 10 AM Thursday to 7 AM EDT Friday
     for ANZ236.
     Small Craft Advisory from 5 AM Thursday to 7 AM EDT Friday for
     ANZ250-254.
     Small Craft Advisory from 5 AM to 10 PM EDT Thursday for
     ANZ251.
     Small Craft Advisory until 7 AM EDT Friday for ANZ256.

&&

$$

SYNOPSIS...Belk/Nocera
NEAR TERM...Belk/Nocera
SHORT TERM...Belk
LONG TERM...Nocera
AVIATION...Belk/Nocera
MARINE...Belk/Nocera