BOX issues Area Forecast Discussion (AFD) at Dec 12, 1:09 PM EST538
FXUS61 KBOX 121809
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
109 PM EST Thu Dec 12 2024
.SYNOPSIS...
Mainly dry, blustery and seasonably chilly temperatures are on
tap for today. Cold/Below normal temperatures with dry weather
will be in place for Friday and Saturday. Pattern trends more
unsettled later Sunday through next week with periods of
precipitation possible. Temperatures moderate to above normal
levels for the early part of next week.
&&
.NEAR TERM /THROUGH TONIGHT/...
Key Messages:
* Breezy and much colder this afternoon and overnight.
* Rouge flurries, mainly across northern MA are possible due to
ongoing lake effect snow.
Cold and quiet conditions this afternoon across the northeast
with an occasional light snow shower as the region is under
cyclonic flow due to the mid-level low pressure system and
deepening 976mb low in northeastern Canada. As mentioned, a few
flurries are possible through the afternoon and evening due to
the metaphoric "snow guns" blasting snow eastward off of Lake
Ontario and Lake Eire. With steep low-level lapse rates, gusts
between 20-30 mph continue this afternoon. When you combine the
wind and the seasonably cooler temperatures which are in the 30s
and low-40s, have apparent temperatures in the 20s and low-30s.
Heading into the overnight hours the gusts diminish, but will
remain elevated with occasional gusts 15 to 20 mph. While sky
cover is trending more clear, the elevated wind gusts should
preclude true radiational cooling - that said, overnight
temperatures dip into the teens to low-20s. Slightly warmer for
the immediate coast and urban centers like Boston are in the
middle 20s.
&&
.SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/...
Key Points...
* Dry & cold tonight with lows mainly upper teens to lower 20s
* Sunny and cold Fri with highs upper 20s to middle 30s
Details...
Friday...
A 1040+ MB high pressure system over the Great Lakes will nose
eastward. This should result in lots of sunshine but it will be
cold. 850T between -14C and -16C should result in high temps in
the upper 20s across the high terrain to mainly between 30 and
35 elsewhere. These readings will be about 10 degrees below
normal of this time of year. Northwest wind gusts around 20 mph
with a few gusts near 25 mph are expected.
&&
.LONG TERM /SATURDAY THROUGH WEDNESDAY/...
Key Messages:
* Dry conditions through the first half of weekend. Pattern leans
unsettled Sun through next week with periods of precipitation
possible.
* Below normal temperatures for the weekend, trending above normal
early next week.
Expect another night of efficient radiational cooling Friday night
with clear skies and cooler air still in place. Temperatures likely
drop into the mid to upper teens across most areas with some low 20s
for some of the coastal locations. The higher terrain spots across
the interior may see lows drop into the lower teens.
Temperatures remain below normal Saturday with highs in the 30s
across southern New England. Winds should stay on the lighter side
keeping wind chill values close to actual temperatures. With high
pressure in place conditions remain dry.
Ensemble guidance continues to show a consensus on a shift to a more
unsettled/active pattern Sunday into next week. There is a general
signal for increased moisture phased with the passage of a few
shortwave troughs in the flow aloft. This will give way to periods
precipitation. However, aside from the ensemble means, individual
models/ens solutions are still displaying differences with respect
to the details of these disturbances, particularly the timing/speed
of the systems. Overall, expect periods of precipitation starting as
early as early Sunday evening through at least mid-week. There is
some potential for light mixed precip/icing for parts of the
interior at the onset of precipitation late Sun, but this is still
low confidence given that there isn't a consensus on timing just
yet. There is a hint of better moisture being in place Tuesday which
may lead to more widespread chances for precipitation.
Ensembles further diverge toward the end of the week. As a result of
differences in the upper pattern, there is uncertainty in
temperatures Thursday with some solutions leaning toward a cooler
airmass in place and others showing a ridge with highs closer to
normal.
&&
.AVIATION /18Z THURSDAY THROUGH MONDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18z TAF Update...
Today...High Confidence.
VFR despite scattered to broken strato-cu around 4-5K feet. WSW
wind gusts of 25 to 30+ knots.
Tonight...High Confidence.
VFR. WSW winds should diminish to between 5 and 10 knots,
occasional gust to 20 kt.
Friday...High Confidence.
VFR. WNW 8-15 knots with some 20+ knot gusts at times.
KBOS Terminal...High Confidence in TAF.
KBDL Terminal...High Confidence in TAF.
Outlook /Saturday through Monday/...
Friday Night: VFR. Breezy.
Saturday through Sunday: VFR.
Sunday Night: Mainly VFR, with local MVFR possible. Slight
chance SN.
Monday: Mainly VFR, with areas IFR possible. Chance RA.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Today...High Confidence.
Westerly wind gusts of 30 to 35 knots are on tap for today in
the cold air advection pattern behind yesterday/s front.
Strongest of the winds will be across the southern waters where
we have Gale Warnings all day. Across our northern waters...we
should be able to replace Gales with small craft headlines later
this morning as gusts will be more on the order of 30 knots. 8
to 15 foot seas over many of our waters will gradually lower
through the day...but they will remain quite rough.
Tonight and Friday...High Confidence.
Cold Advection over the relatively mild ocean will result in W
wind gusts of 20 to 30 knots persisting over the open waters
tonight into Friday. We will need small craft headlines for many
waters.
Outlook /Saturday through Monday/...
Friday Night: Winds less than 25 kt. Seas locally approaching
5 ft.
Saturday through Sunday: Winds less than 25 kt.
Sunday Night: Winds less than 25 kt. Slight chance of rain.
Monday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 10 PM EST this evening for ANZ230-
236.
Small Craft Advisory until 1 AM EST Friday for ANZ231-251.
Gale Warning until 5 PM EST this afternoon for ANZ232>235-237-
254>256.
Small Craft Advisory until 7 AM EST Friday for ANZ250.
&&
$$
SYNOPSIS...Dooley/Mensch
NEAR TERM...Dooley
SHORT TERM...Frank
LONG TERM...Mensch
AVIATION...Dooley/Mensch
MARINE...Frank/Mensch
Source:
BOX issues Area Forecast Discussion (AFD) at Dec 12, 1:09 PM EST----------------
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