BOX issues Area Forecast Discussion (AFD) at Dec 1, 4:06 PM EST163
FXUS61 KBOX 012106
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
406 PM EST Sun Dec 1 2024
.SYNOPSIS...
Below normal temperatures and mainly dry conditions early next
week with the exception of some offshore ocean effect rain/snow
showers. Next chance for precipitation comes late Wednesday
through Thursday bringing rain or light snowfall. An even colder
airmass moves in Friday and into the weekend, likely with the
coldest air of the season thus far.
&&
.NEAR TERM /UNTIL 6 AM MONDAY MORNING/...
As expected, this afternoon feels much like yesterday afternoon as
we've seen little change in the overall pattern with low pressure to
the north and high pressure to the south. As the high nears, the
pressure gradient further slackens and we'll see this morning's
breezy winds diminish toward sunset. Overnight this sets SNE up for
efficient radiational cooling, so have trended the forecast toward
MOS guidance, predicting lows in the teens and low 20s. Dry forecast
save for the islands where there remains the slight chance of a
passing ocean effect rain shower through this evening.
&&
.SHORT TERM /6 AM MONDAY MORNING THROUGH MONDAY NIGHT/...
Key Points...
* A quiet and cold start to the week.
Monday high pressure approaches as the low exits further northeast,
so while we're still beneath a mid level trough, heights will be
rising and the column remains very dry (PWATs <0.2"). So, expecting
another sunny and dry day with below normal highs thanks to that
trough/cold airmass overhead. Looking at another day with highs
around 10 degrees colder than average, in the mid to upper 30s.
Another repeat Monday night with good radiational cooling and lows
in the teens (interior) and low 20s (along the coast).
&&
.LONG TERM /TUESDAY THROUGH SUNDAY/...
Key Messages:
* Below normal temperatures favored next week, trending even colder
by next weekend.
* Next chance for rain/snow Wednesday evening through Thursday.
Ensemble guidance is in good agreement with the general set-up of
upper ridging to the west and a trough over the northeast. This will
allow a cooler airmass settle across the northeast resulting in
below normal temperatures. Tuesday and Wednesday trend on the drier
side with highs ranging from mid 30s (higher elevations) to low 40s
(coastal locations). With ocean temperatures near 50, can't rule out
low chances for ocean effect rain/snow showers each day, mostly
offshore. Overnight, temperatures drop into the upper teens across
the high elevation spots and 20s elsewhere.
A shortwave trough and accompanying cold front move through
Wednesday night to Thursday which will bring the next chance for
precipitation. Model guidance continues to track the upper low north
of the region along with the main batch of synoptic energy/forcing
and moisture is marginal. Despite this, there is just enough support
for precipitation developing from west to east Wednesday night.
Given the cool air in place, this could mean that light snow or a
rain/snow mix is possible Wednesday night into Thursday morning.
Snow will be more favored in the high elevation spots (above 1 kft)
and the MA interior. Ensemble guidance continues to display
probabilities for greater than 1" of snow ranging from 20 percent in
east MA to upwards to 80%+ across the west slope of the Berkshires.
Elsewhere sits at 30-50% with the exception of the Cape which likely
won't have accumulation. For 3" or greater, probabilities of 20-50%
stay confined to the Berkshires and Worcester Hills, perhaps locally
higher probs for the highest elevation spots. There is potential for
snow or a rain/snow mix toward the coastal areas overnight; however,
these areas have lower probabilities for > 1" (10-45%).
In other words, 1-4 inches looks to be the range highlighted by
ensembles right now with the best chances for accumulation for the
interior and especially the higher elevations. Closer to the coast,
there's the risk of a rain/snow mix which will limit accumulation,
but still may see a little snow before it warms up Thursday morning.
This could mean that flakes may be falling during the AM commute
Thursday, but given the light nature of accumulations, not expecting
major impacts.
A few rounds of showers may shift through on Thursday before the
main front pushes across. We'll have to keep monitoring to see how
strong the CAA will be behind the front Thursday afternoon/evening
as this could be a flash freeze issue if strong enough. Too early to
tell at this point, but there is a general signal there with model
snow squall parameter fields highlighting the push of cool air with
some instability with it. What we do know is that is will get COLD.
Thursday night into Friday, an arctic airmass advects in behind the
system bringing in the coldest air so far this season. This will
support highs in the upper 20s and 30s with most areas struggle to
get above freezing by Saturday. Nights will be chilly with lows
dropping into the low 20s for the coast and teens across the
interior.
The Late Weds-Thurs system will also bring windy conditions to the
region increasing Wednesday night into Thursday continuing through
Friday. Gusts 20-30 mph possible. This will be important Friday
given the cold air which in combination will bring apparent
temperatures into the teens and low 20s during the day Friday.
&&
.AVIATION /21Z SUNDAY THROUGH FRIDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
18Z update...
Through Monday: High confidence.
VFR, though there could be continued ocean-effect clouds at
borderline VFR/MVFR levels at ACK. Can't rule out a few brief ocean
effect rain/snow showers today into Monday at ACK. Low chance
for MVFR/IFR CIGS towards the Berkshires. WSW winds today with
gusts up to 20 kt this afternoon for the coastal terminals.
Winds turn WNW late tonight into Monday and Monday night,
becoming light after Sunday afternoon.
KBOS Terminal...High confidence in TAF.
KBDL Terminal...High confidence in TAF.
Outlook /Tuesday through Friday/...
Tuesday through Tuesday Night: VFR.
Wednesday: VFR. Breezy.
Wednesday Night: MVFR/IFR conditions possible. Breezy. RA
likely, SN likely.
Thursday: Mainly VFR, with local IFR possible. Windy with gusts
up to 30 kt. Chance RA, chance SN.
Thursday Night: VFR. Windy with gusts up to 35 kt. Slight
chance SN.
Friday: VFR. Windy with areas of gusts up to 30 kt.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Gusty W winds up to 25 kt continue across the waters this
afternoon. Rough seas linger across the southern outer coastal
waters into tonight, before finally subsiding below 5 feet.
Small Craft Advisories continue into tonight. Slight chance of
rain or snow showers Sunday afternoon then again Monday night.
Outlook /Tuesday through Friday/...
Tuesday: Winds less than 25 kt. Slight chance of rain.
Tuesday Night: Winds less than 25 kt. Chance of rain.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Chance of rain.
Wednesday Night: Moderate risk for Small Craft Advisory winds
with gusts up to 30 kt. Areas of rough seas. Rain.
Thursday: Strong winds with gusts up to 35 kt. Rough seas up to
14 ft. Rain likely.
Thursday Night: Strong winds with gusts up to 40 kt. Rough seas
up to 14 ft. Chance of rain, slight chance of snow.
Friday: Strong winds with gusts up to 35 kt. Rough seas up to
11 ft. Slight chance of snow.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until midnight EST tonight for ANZ254-256.
Small Craft Advisory until 4 AM EST Monday for ANZ255.
&&
$$
SYNOPSIS...BW/Mensch
NEAR TERM...BW
SHORT TERM...BW
LONG TERM...Mensch
AVIATION...BW/Mensch
MARINE...BW/Mensch
Source:
BOX issues Area Forecast Discussion (AFD) at Dec 1, 4:06 PM EST----------------
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