BOX issues Area Forecast Discussion (AFD) at Mar 29, 2:02 PM EDT815
FXUS61 KBOX 291802
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
202 PM EDT Sat Mar 29 2025
.SYNOPSIS...
Raw and chilly weather is on tap for the weekend along with a
few showers at times as well as areas of fog and drizzle. In
fact...temperatures will be cold enough to support some light
freezing rain/freezing drizzle in the highest terrain of the
Berkshires and Worcester Hills later today and especially
tonight. A warm front will cross the region late Sunday night or
Monday morning...bringing much milder temperatures by Monday
afternoon. A cold front will bring showers along with the risk
of downpours and a rumble or two of thunder late Monday/Monday
night. Dry weather returns Tuesday and Wednesday with
temperatures trending cooler. Milder temperatures return
Thursday and Friday with perhaps a round of showers.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Update...
Cloud cover over central CT is continuing to keep temperatures
in the 40s, but appears to be trying to break up a bit. Once
this clearing happens, temperatures can be expected to rise into
the mid 50s. Will continue to monitor as the day goes on.
Fog and drizzle are still expected to persist through the rest
of the day.
Previous discussion...
Key Messages:
* Stationary boundary bisects southern New England leading to a
stark contrast in temperatures with mild air south of the boundary
and cold air north of the boundary.
* Showers, areas of fog and drizzle for much of today. A lower
chance for pockets of freezing rain in higher terrain (areas AOA
1,000 ft) due to near freezing surface temperatures, with a better
chance tonight into Sunday morning.
* Winter Weather Advisory issued for the higher terrain of northern
and western Massachusetts for ice accretion.
Latest WPC surface analysis shows the stationary boundary extending
from west to east, bisecting Massachusetts. Able to see this when
looking at area ASOS, with the wind on the north side of the front
out of the north to northeast, while south of the front the winds
are out of the south to southwest. A perfect example, KBAF has a
northerly wind while KBDL has a southerly wind, sites are 15 miles
apart! Early this morning have a wave of low pressure riding the
front with areas of light rain, there are little impacts associated
with this first round of precipitation as temperatures remain above
freezing. Rain comes to an end by midmorning, while the rest of the
day isn't a washout, likely an overcast day with showers for areas
in northern Massachusetts, while rest of southern New England has
areas of fog and drizzle due to the high moisture content trapped in
the lowest levels. Now, temperatures in far northern Massachusetts
(along the border with NH and VT) will be close to freezing, will
have to be cautious of freezing rain or freezing drizzle, with the
potential for minor ice accumulation (areas AOA 1,000 ft) tonight
into Sunday morning and because of that a Winter Weather Advisory
was issued from 8am this morning through 11am Sunday for northern
Worcester County, northwest Middlesex County, and western Franklin
and Hampshire Counties. The risk if for ice accretion up to 0.1"
with a low risk of up to 0.2".
As advertised, today is the battle between two different air masses
and much of southern New England will be on the colder side. But a
few locations will briefly warm into the 50s mainly in Connecticut
and southern Rhode Island. Not too far off, southwestern Connecticut
will top out in the middle 70s to perhaps 80F! A stark contrast to
northcentral and northeastern Massachusetts, where the temperatures
this afternoon are in the low and middle 30s! This is because of a
strong high pressure system in eastern Canada, locking in the colder
air. Looking at 925mb it is easy to see the wide temperatures spread
across the region, from -5C at BOS to +10C at HFD. Look at 850mb and
there is a fairly uniform air mass at +6C to +8C! Not much changed
with the position of the boundary, does look to bisect southern New
England from the northwest to the southeast, roughly from Pittsfield
to Springfield to Providence to New Bedford. Leaned heavily on a
blend of the high-res guidance (CONSAll, HREF, NAM 3KM, and HRRR)
this give a few hours of daytime heating south of the boundary
before the front shifts southwest towards the Mid Atlantic.
In general, this is a fairly sensitive set up, if the boundary were
to shift either north or south by +/- 25 miles cities like Hartford,
Springfield, and Providence have potential to have a significant
bust temperature wise given the close proximity to the boundary.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Key Messages:
* Icing threat overnight for higher elevations of northern and
western Massachusetts.
* Cold and raw Sunday a few showers or drizzle at times. Pockets of
freezing rain or drizzle possible through the morning over higher
elevations north of Route 2.
Tonight: As the front moves south and out of the region temperatures
will continue to lower into the 30s, areas AOA 1,000 ft are near or
below freezing, 30F to 32F. It is here where we have confidence in
minor ice accretion, less than 0.1" with a low risk of up to 0.2",
anyone traveling should exercise caution. This area is covered in
the current Winter Weather Advisory, where we have lower confidence
in minor icing/glaze would be interior Essex County, as there is the
potential for similar temperatures, but given the lower elevation
and warmer ground temperatures, feel it would be difficult for ice
to accumulate. If confidence were to increase, may want to expand
the advisory. Elsewhere, a cold and raw night, showers, areas of
drizzle and fog with temperatures in the middle and upper 30s.
Sunday: Cold and raw conditions continue, occasional showers or
drizzle at times, especially north of I-90 where better moisture is
available, while locations near the south coast may remain mostly
dry Sunday as some drier air moves up from the south. Still could
see some pockets of freezing rain or drizzle in the morning over
higher elevations north of Route 2 where temperatures hover around
freezing. The afternoon temperatures only reach the upper 30s across
northern Massachusetts, low to mid 40s in eastern Massachusetts,
eastern Connecticut, and Rhode Island. Areas west of Hartford reach
the upper 40s to low 50s. That said, should have a non-diurnal night
with the warmest temperatures possibly around midnight heading into
Monday.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key Messages:
* Scattered showers with areas of drizzle and fog persist Sun night
* Turning much milder Mon with a period of widespread showers late
Mon/Mon night with a rumble of thunder & downpours possible too
* Dry weather Tue & Wed with temps trending cooler
* Milder temps arrive Thu into Fri along with the risk for a round
of showers sometime...but confidence is low
Details...
Sunday night...
Scattered showers along with areas of drizzle and fog will persist
Sun night. This as a modest southerly LLJ attempts to over run the
backdoor cold front at the surface...which will be initially
positioned south of our region. We do expect the showers to be more
numerous across northern MA...given better forcing/deeper moisture.
Some of the global guidance allows a warm front to lift northward
across the region. Tend to lean more towards the high resolution
models which indicate slow northward progress given it is as night
and the time of year. So good chance temps hold in the 30s and 40s
during the evening...perhaps rising toward daybreak Mon.
Monday and Monday night...
Low pressure will be tracking to our north across Quebec with a cold
front extending southward. This will allow the surface warm front to
lift north of the region on Mon and afternoon highs will probably
recover into the 60s with a gusty southerly wind. In addition...a
southerly LLJ of 50-60 knots will develop ahead of the cold front
and allow Pwats to rise to between 1.25 and 1.50 inches.
Lastly...the guidance indicates a few hundred J/KG of elevated Cape.
Putting all these ingredients together...expect a period of
widespread showers late Mon/Mon night ahead of the approaching cold
front. Given the southerly LLJ and Pwat plumes 2-3 standard
deviations above normal coupled with some elevated
instability...downpours along with a rumble or two of thunder will
be possible. We may see a solid 0.50 to 1" of rainfall late Mon/Mon
might with the front and perhaps some localized higher amounts.
Tuesday and Wednesday...
Canadian high pressure will nose down into southern New England
bringing a return to dry weather with temps trending cooler. Highs
may still break 50 in many locales Tue. However...shallow cool air
will ooze southward into the region late Tue into Wed. Lows by Tue
night will be well down into the 20s to the lower 30s with highs on
Wed mainly in the 40s to perhaps near 50 in the lower CT River
Valley.
Thursday and Friday...
The high pressure system moves off the coast by late in the work
week. This combined with an approaching cold front will result in
milder temps Thu into Fri. We also may see a round of showers
sometime Thu and/or Fri ahead of the cold front...but confidence is
low at this time.
&&
.AVIATION /18Z SATURDAY THROUGH WEDNESDAY/...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18z TAF Update...
Tonight...High Confidence.
IFR-LIFR ceilings with scattered showers along with areas of
drizzle and fog. Pockets of light freezing rain/freezing drizzle
likely in the high terrain of the Worcester
Hills/Berks. ENE winds 5-10 knots.
Sunday...High Confidence.
IFR conditions continue Sunday with localized LIFR conditions
in any scattered showers, drizzle and fog mainly Sunday
morning. Some improvement to marginal MVFR conditions are
possible across the CT River Valley. Spotty pockets of FZDZ
possible for the higher elevations, but any residual shower
should transition to liquid by mid-morning. E winds at 6-12 kts,
perhaps a bit stronger over the Cape/Islands.
BOS TAF...High confidence in TAF.
BDL TAF...High confidence in TAF.
Outlook /Sunday Night through Wednesday/...
Sunday: Mainly IFR, with areas MVFR possible. Patchy BR, chance
FZRA, slight chance RA.
Sunday Night: Mainly IFR, with areas MVFR possible. Breezy.
Chance SHRA, areas BR, patchy DZ.
Monday: Mainly MVFR, with areas IFR possible. Windy with gusts
up to 30 kt. Chance SHRA, areas BR.
Monday Night: Mainly IFR, with areas MVFR possible. Windy with
areas of gusts up to 30 kt. SHRA.
Tuesday: Mainly VFR, with local MVFR possible. Breezy.
Tuesday Night: VFR. Breezy.
Wednesday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Saturday through Sunday: High Confidence.
A front stalls across the waters through Saturday night. ENE winds
across the eastern waters, with W to SW winds across the southern
waters. Gusts are likely to remain below 25 kt, do expected rough
seas to develop across the outer coastal waters through Sunday. Thus
a Small Craft Advisories posted for this time frame. Additionally,
low clouds, periods of rain, drizzle, and fog are likely during this
time frame along with poor visibility.
Outlook /Sunday Night through Wednesday/...
Sunday: Winds less than 25 kt. Areas of seas approaching 5 ft.
Patchy fog, slight chance of rain.
Sunday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of
rain showers, areas fog, patchy drizzle. Local visibility 1 to
3 nm.
Monday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Areas of rough seas. Chance of rain showers, areas
fog.
Monday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Rough seas up to 10 ft. Rain showers.
Visibility 1 to 3 nm.
Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas. Chance of rain showers.
Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of rough seas.
Wednesday: Winds less than 25 kt. Seas up to 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Winter Weather Advisory until 11 AM EDT Sunday for MAZ002>004-
008-026.
RI...None.
MARINE...Small Craft Advisory until 8 AM EDT Sunday for ANZ235-237.
Small Craft Advisory until 4 AM EDT Sunday for ANZ250.
Small Craft Advisory until 2 PM EDT Sunday for ANZ254.
Small Craft Advisory until 8 PM EDT Sunday for ANZ255-256.
&&
$$
SYNOPSIS...Frank/Dooley
NEAR TERM...Dooley/Hrencecin
SHORT TERM...Dooley
LONG TERM...Frank
AVIATION...Hrencecin/Mensch
MARINE...Frank/Dooley
Source:
BOX issues Area Forecast Discussion (AFD) at Mar 29, 2:02 PM EDT----------------
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