BOX issues Area Forecast Discussion (AFD) at Jan 7, 6:34 PM EST996
FXUS61 KBOX 072334
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
634 PM EST Tue Jan 7 2025
.SYNOPSIS...
Cold temperatures, blustery to gusty northwest winds and dry
weather will prevail for much of this week. Dry weather will
continue on Friday, but temperatures will modify a bit from
earlier in the week along with less wind. Odds favor a coastal
low pressure passing too far south of the region Saturday to
bring us a major winter storm, but deliver more of a glancing
blow/miss. That being said...the forecast is still 4 days in the
future and a higher impact still can not be ruled out.
Regardless...dry and cold weather follow early next week.
&&
.NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/...
340 PM Update:
Key Messages:
* Windy and cold tonight with dry weather. Wind chills 0 to 10 below.
* Strong winds in the higher terrain of western and central MA. Wind
Advisory issued, although minimal impact.
Southern New England remains entrenched in a tight NW gradient
between slow moving strong low pressure over the Canadian Maritimes
and a strong 1040+ mb high pressure over the Northern Plains. This
enhanced northerly flow is helping to draw a modified-Arctic airmass
southward. Cold air aloft is helping to create gusty conditions even
though mixing is pretty shallow. So far, northwest gusts have been
commonly around 30-35 mph today, although a few areas in the higher
terrain in the Berkshires and central MA have gusted between 40 to
at times up to 50 mph. This has prompted the issuance of Wind
Advisories for these locations, although with trees devoid of leaves
and no snow weighing on them, other than a few downed branches and
perhaps pretty isolated power outages, impacts from this Advisory
should be overall pretty minimal. The Wind Advisory has been
extended into Wednesday night, with northwest gusts expected to be
be similar or perhaps a touch higher expected, but even then,
impacts should be limited.
The main effect the winds even outside of the Advisory will have is
to produce low wind chill temperatures. While the air temps will be
slow to fall, leading to low temps in the single digits to the
mid/upper teens, the combined chilling effect of the wind should
produce apparent temps around 0 to 10 below zero. Lowest readings to
be confined to the higher terrain where temps are coldest and wind
gusts are the strongest. While these fall short of dangerous levels,
it is the first we've seen wind chills dip to this degree, and those
bringing children to the bus stop early Wednesday morning should
ensure they are bundled up with layers to prevent exposure.
&&
.SHORT TERM /6 AM WEDNESDAY MORNING THROUGH WEDNESDAY NIGHT/...
340 PM Update:
Key Messages:
* Continued dry and windy with below normal temps. Daytime wind
chills 5 below to 10-15 above zero, 0 to 10 below Wed night.
* Gusty to strong northwest winds continue, and though gusts could
be a little higher than on Tue, impacts should be minimal.
Details...
Large-scale weather pattern for Wednesday is generally quite similar
to today, with cold temperatures and gusty NW winds along with dry
weather. However the core of the strongest cold air moves in for
Wednesday as 925 mb temps fall to around -13 to -15C! So the peak of
the cold air settles into the region on Wed. Highs on Wed may
struggle to reach the mid 20s into the coastlines, and the interior
high terrain may not get to 20 degrees. Clear skies initially
for Wed night but may become more of a partly to mostly cloudy
look given the enhanced flow off the Gt Lakes leading to areas
of stratocumulus, with lows in the upper single digits to the
mid to upper teens.
On the winds...we expect wind gusts to increase again shortly
after sunrise. NW low level jet strength is progged to be about
5 kt stronger than today, around 35 to 45 kt. Inversion height
is pretty low, which could favor areas in and around the higher
terrain to gust to 50 mph on Wed. Gusts elsewhere should reach
into the 30-40 mph range. This is also consistent with HREF 10-m
minimum gust speeds, which shows local maxima in the higher
terrain at similar values to today. After coordination with NWS
Albany, we've extended the wind advisory into Wed night. Gusts
should slowly ease some into Wed night, but will still be quite
breezy into the evening.
&&
.LONG TERM /THURSDAY THROUGH TUESDAY/...
Key Points...
* Windy & Cold Thu with highs mainly in the upper 20s/lower 30s
* Continued Dry Fri but a bit milder with less wind...Highs 35-40
* Odds favor glancing blow/miss on Sat storm...light snow possible
* Dry & seasonable cold weather returns early next week
Details...
Thursday...
Strong low pressure over the Canadian Maritimes will combine with a
ridge of high pressure across the Ohio Valley. This will continue to
result in northwest wind gusts of 30-40 mph and cold temperatures.
We may see a few 45+ mph wind gusts...but overall thinking
conditions will be just below wind advisory criteria. Highs should
be held in the upper 20s to the lower 30s...but given the windy
conditions it will feel colder! Dry weather will prevail outside
perhaps a brief passing spot flurry from remnant Lake Effect
moisture.
Friday...
The ridge of high pressure shifts east towards southern New England
on Fri. This will weaken the pressure gradient...so it will still be
breezy but not as windy as the past few days. 925T rebound a
bit...so we should see highs recover into the 35-40 degree range for
much of the region.
Saturday...
All attention revolves around a low pressure system that will be
emerging from the Gulf Mexico late this week and lifting northeast
Fri into Sat. How far north this system will get depends upon on
much the northern stream energy can dig and amplify the upper level
flow. Based on the latest trends and most of the supporting
guidance...odds favor a glancing blow/miss to the south with this
system. The shortwave does not appear to dig enough which allows the
low to pass too far south to deliver a major snowstorm in our region.
That being said...this storm is still 96-120 hours out in the model
world and we still can not rule out a more significant impact. While
most of the GEFS/EPS/CMC individual ensembles indicate a glancing
blow/miss...there are a few that indicate a larger impact with most
of those being GEFS members.
So in a nutshell...odds favor a glancing blow/miss but still can not
rule out a larger impact until at least Wed, Regardless...we may see
a period of light snow Sat with just the northern stream upper level
energy separate from the main system.
Sunday/Monday/Tuesday...
Dry and cold weather is the main weather story early next week. We
are still looking at generally a -NAO/+PNA across the region. This
should result in seasonable to a bit below normal temps early next
week. Trough axis looks to be too far east to support much if any
precipitation over this time...other than perhaps a brief passing
flurry from remnant Lake moisture.
&&
.AVIATION /00Z WEDNESDAY THROUGH SUNDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
00z TAF Update...
Tonight through Wednesday Night: High confidence.
VFR through the period. The main concern is the strong NW wind
gusts of 25 to 40 knots. The strongest of those winds will be
during the daylight hours of Wednesday with a few gusts of 40-45
knots possible especially in the high terrain.
KBOS TAF...High confidence in TAF.
KBDL TAF...High confidence in TAF.
Outlook /Thursday through Sunday/...
Thursday through Thursday Night: VFR. Windy with gusts up to
35 kt.
Friday: VFR. Windy with local gusts up to 30 kt.
Friday Night: Mainly VFR, with local IFR possible. Slight
chance SN.
Saturday: Mainly IFR, with local MVFR possible. Breezy. Chance
SN.
Saturday Night: Mainly VFR, with local IFR possible. 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.
Tonight through Wednesday Night: High confidence.
Gale Warnings have been extended into Thursday on most waters, with
a rather prolonged period of northwest gusts into the 30-40 kt
range. Expect the strongest gusts - in the solid Gale force range -
to take place during the daytime hours, with gusts closer to the 30-
35 kt range during the evening hours (tonight and Wed night). Wave
heights of 5-10 ft are expected through the forecast period with
little change, highest values offshore with wave heights on the
lower end of that range in the coastal/nearshore zones, with bays
around 1-2 ft.
Note that the cold air and strong winds are likely to favor
minor accretion of freezing spray on vessels navigating through
Southern New England's coastal waters.
Outlook /Thursday through Sunday/...
Thursday: Moderate risk for gale force winds with gusts up to
35 kt. Areas of rough seas. Freezing spray.
Thursday Night: Strong winds with gusts up to 35 kt. Areas of
rough seas.
Friday: Moderate risk for Small Craft Advisory winds with gusts
up to 30 kt. Local rough seas.
Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of snow. Areas of visibility 1 to 3 nm.
Saturday: Winds less than 25 kt. Chance of snow. Visibility
1 to 3 nm.
Saturday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 25 kt. Local rough seas. Chance of snow.
Visibility 1 to 3 nm.
Sunday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Areas of rough seas.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...Wind Advisory until 1 AM EST Thursday for MAZ002-004-008-009-
012-026.
RI...None.
MARINE...Gale Warning until 7 PM EST Thursday for ANZ230>235-237-250-
251-254>256.
Small Craft Advisory until 1 PM EST Thursday for ANZ236.
&&
$$
SYNOPSIS...Loconto/Frank
NEAR TERM...Loconto
SHORT TERM...Loconto
LONG TERM...Frank
AVIATION...Loconto/Frank
MARINE...Loconto/Frank
Source:
BOX issues Area Forecast Discussion (AFD) at Jan 7, 6:34 PM EST----------------
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