BOX issues Area Forecast Discussion (AFD) at Feb 8, 3:59 AM EST448
FXUS61 KBOX 080859
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
359 AM EST Sat Feb 8 2025
.SYNOPSIS...
Quiet for most of today. A snowstorm is on tap tonight into
Sunday morning, with perhaps some mixing at the end of this
storm near the south coast and islands. Drying out Sunday night
through Tuesday, with a period of below normal temperatures and
limited if any snowmelt from tonight's storm. Our weather
pattern then becomes more active again with a coastal low
pressure passing to our south Tuesday night into Wednesday that
may bring light snow, and monitoring a stronger storm around
late next week.
&&
.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Key Messages:
* Rather tranquil and slightly colder today
High pressure moving offshore will maintain rather quiet weather
across southern New England today. Expecting slightly lower
temperatures, which will set the stage for some snow later
tonight. Some sunshine this morning, with increasing clouds this
afternoon.
&&
.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/...
Key Messages:
* Snowstorm moves across southern New England tonight into
Sunday morning.
* Medium confidence in snow totals, with a most likely range of
4-8" across southern New England.
* Potential for freezing drizzle/snizzle on back end of storm Sunday
AM.
Latest guidance suite trended slightly slower with the timing of
this event. While surface temperatures across most of our region
should not be a problem for supporting snowfall, there are still
some uncertainties that lower confidence in these snowfall
totals. The first is the duration of this storm. It's moving
fast, and should persist for only about 12 hours or so. As it
looks now, we have about a 4-5 hour period where the conditions
line up best to produce higher snowfall rates (from about 10 PM
to 3 AM). A shorter duration would cut back on snowfall
amounts.
Another issue is the expectation of drier air moving into the
dendritic growth zone (DGZ) after midnight. This can have the
effect of making smaller snowflakes or freezing rain instead.
Neither is good for accumulating snow. As of this writing, still
have the greatest confidence this will impact areas south of
the Mass Pike, but there is a risk for it moving farther north.
The 08/00Z NAM is the slowest to do this, but even it brings the
dry air in the DGZ to the NH/VT/MA border by daybreak Sunday.
This will need to be monitored through today.
Considering all of this, have the highest confidence in 4-8" of
snow across most of southern New England, which is enough to
convert Winter Storm Watches to Warnings. Towards the Cape and
islands, am thinking there are just too many issues to have
confidence in averaging 6" of snow. Winter Weather Advisories
posted there instead. Subtle changes over the next 24 hours may
alter this forecast further.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key Messages:
* Quiet to start the week through Thursday, slightly colder than
normal but dry
* Low pressure moving off the mid-Atlantic coast Tuesday night
being monitored for possible light snow, but details remain
uncertain
* Stronger system possible Thursday, but the track and
precipitation types remain uncertain this far out
Sunday night through Tuesday...
High pressure builds in and remains over southern New England
into Tuesday. Forecast soundings across the region Monday
indicate good mixing, and with 925 mb temperatures sitting
around -10C for much of the day, slightly colder than normal
temperatures can be expected. Highs for Monday will likely be in
the low to mid 30s across the region with some spots in the
higher elevations sitting in the 20s. Lows Sunday night will
likely be in the teens and low 20s, but are expected to sink to
single digits and teens for Monday night with the cold airmass
settling over the region. Since these temperatures aren't
expected to climb much higher during these few days, not much
snowmelt can be expected to start the week.
Tuesday night...
A shortwave disturbance from the Rockies is expected to progress
eastward and a surface low will likely develop ahead of it
across the central US. This will likely reach the mid-Atlantic
by Tuesday night. Precipitation and track are still quite
uncertain at this time. Ensemble guidance at this time keeps the
highest probabilities for QPF >0.1 inches over 24 hours (ending
00z Thurs) to the South Coast, with probs ranging from 50% to
75% up into RI and along the Cape. Probs are below 50% towards
Boston and north. The one ensemble that has notably low probs is
the GEFS, which also tracks the system well to the south and
east offshore. This is also evident in the GFS compared to the
other deterministic models. If this system does pass along/just
south of the South Coast, some light snow could accumulate,
especially with the colder temperatures aloft still in place.
Wednesday through Friday...
Brief high pressure looks to return following the passage of
Tuesday night's low. A notably stronger shortwave from the
Rockies moving east is expected to produce a stronger surface
low out ahead of it that may reach the Northeast by Thursday
morning. As it is still quite far out, timing, track, and ptype
are not nailed down at this time. Ensemble solutions are leaning
towards taking this low's center along the South Coast or just
south of it, and when coupled with possible warmer temperatures
aloft (925 mb temperatures reaching 0C and slightly above), this
could encourage a mix of winter precipitation types. The extent
that the low's associated WAA extends north will be a key
factor here, and with the spread in possible tracks across all
models, this remains uncertain. The ECMWF shows a primary low
passing to our northwest with a secondary low developing over
southern New England before undergoing more intense cyclogenesis
over the Gulf of Maine as it moves off into the Maritimes, but
as of the time of this writing, this is the one model with that
track. PoPs were reduced to Likely at the highest across the
extended period.
&&
.AVIATION /08Z SATURDAY THROUGH WEDNESDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Today...High Confidence
VFR. W winds 5-10 knots shift to more of a SW direction by late
afternoon.
Tonight and Sunday...High Confidence.
IFR/LIFR conditions rapidly develop this evening as snow
overspreads the region from southwest to northeast between 00z
and 03z Sun. The snow will fall heavy at times into the
overnight hours with 1-2" per hour rates at times. Brief change
over to rain/sleet is possible for mainly the Islands.
Snow winds down from west to east Sun morning, but will linger
longest across central and eastern MA. Improvement to VFR will
occur during the afternoon across western MA/CT, but lower cigs
may linger a bit longer across eastern MA with even a few left
over snow showers/flurries near the coast.
Light S winds Sat evening become NE by daybreak Sun. Winds then
shift to the NW Sun afternoon.
KBOS TAF...High Confidence in TAF. Snow arrives near 02z/03z Sun.
KBDL TAF...High Confidence in TAF. Snow arrives near 00z/01z
Sun.
Outlook /Sunday Night through Wednesday/...
Sunday Night: VFR.
Monday: VFR. Breezy.
Monday Night: VFR.
Tuesday: VFR. Slight chance SN.
Tuesday Night: Mainly VFR, with local IFR possible. Chance SN.
Wednesday: Mainly VFR, with local MVFR possible. Slight chance
SN.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High- greater than 60 percent.
Overall high confidence through Saturday.
Small Craft Advisories continue on the outer coastal waters as
winds continue to decrease. A low pressure should move east
around the 40N parallel. Rough seas should redevelop across the
outer coastal waters Sunday. Will likely need Small Craft
Advisories again.
Outlook /Sunday Night through Wednesday/...
Sunday Night: Winds less than 25 kt. Seas up to 5 ft.
Monday through Monday Night: Winds less than 25 kt. Areas of
seas approaching 5 ft.
Tuesday: Winds less than 25 kt. Chance of snow.
Tuesday Night: Winds less than 25 kt. Chance of snow. Local
visibility 1 nm or less.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of snow.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...Winter Storm Warning from 7 PM this evening to 1 PM EST Sunday
for CTZ002>004.
MA...Winter Storm Warning from 7 PM this evening to 1 PM EST Sunday
for MAZ002>021-026.
Winter Weather Advisory from 7 PM this evening to 1 PM EST
Sunday for MAZ022>024.
RI...Winter Storm Warning from 7 PM this evening to 1 PM EST Sunday
for RIZ001>007.
Winter Weather Advisory from 7 PM this evening to 1 PM EST
Sunday for RIZ008.
MARINE...Small Craft Advisory until 7 AM EST this morning for ANZ250-
254>256.
&&
$$
SYNOPSIS...Belk/Hrencecin
NEAR TERM...Belk
SHORT TERM...Belk
LONG TERM...Belk/Hrencecin
AVIATION...Belk/Hrencecin
MARINE...Belk/Hrencecin
Source:
BOX issues Area Forecast Discussion (AFD) at Feb 8, 3:59 AM EST----------------
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