Carolina, Rhode Island 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

641
FXUS61 KBOX 231728
AFDBOX

Area Forecast Discussion
National Weather Service Boston/Norton MA
1228 PM EST Mon Dec 23 2024

.SYNOPSIS...
Ocean effect flurries end early this afternoon followed by a
dry and continued cold Monday, but temperatures moderate
slightly. A weak clipper system may bring very minor snow
accumulations late Monday night into Christmas Eve morning.
Otherwise, dry weather dominates the rest of the Holiday week
into next weekend with seasonably chilly temperatures.

&&

.NEAR TERM /UNTIL 6 PM THIS EVENING/...
Updated: 9:35 AM

Key Messages:

* Lingering flurries come to an end near Cape Cod.

* Sunny and chilly this afternoon as the Arctic high centers over
  the northeast.

Forecast is on track and only minor adjustments made. Radar
shows lingering ocean effect flurries from near Plymouth to
Cape Cod but we have noted a diminishing trend as daytime
"heating" has started to disrupt banding. Soundings show
conditional instability and well-aligned low level NNE flow
persisting through early afternoon, so flurries will hang on for
a few more hours, but on a larger scale, ridging at 850 mb and
below working into region this afternoon will begin to squash
this activity as subsidence increases.

Otherwise, high pressure over region will lead to plenty of
sunshine and light winds. 925mb temperatures begin to moderate,
-12C to -8C, while still chilly, highs are in the middle to
upper 20s, with far northwest Massachusetts still in the upper
teens to lower 20s. Clouds increase during the afternoon as a
warm front approaches ahead of a weak clipper system.

&&

.SHORT TERM /6 PM THIS EVENING THROUGH 6 PM TUESDAY/...
Updated: 3:30 AM

Key Messages:

* Light snow late tonight into Tuesday morning from a weak clipper
  system passing to our north.

* Berkshires and northern Worcester Hills have the best chance of
  receiving more than an inch of new snow.

Weak clipper system tracks across northern New England overnight and
exits the northeast early Tuesday afternoon. A warm front approaches
late this evening, leading to light snow showers along and north of
the Mass Pike. Temperatures remain below freezing, so any precip
would come down as snow. With the passage of the warm front winds
become southwest, leading to a non-diurnal temperature trend
overnight into Tuesday morning. In fact, the coldest part of the
night could be between 10pm and 2am, with temperatures in the teens
and low 20s, and then followed by increasing temperatures through
sunrise. Many locations remain below freezing, but coastal
southeastern Massachusetts warms to the low to mid-30s by sunrise.

Trailing cold front pushes through the region from the predawn hours
and then exits eastern coastal Massachusetts early afternoon. Minor
snow accumulations for the northern Worcester Hills and Berkshires,
where one to two inches are possible, elsewhere the lower elevations
see a coating to an inch. Regardless, this system will not produce
much precipitation and ends by early afternoon. Highs recover into
the 30s, to as warm as 40 for Cape Cod and islands.

&&

.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Updated: 3:30 AM

Key Messages...

* Mainly dry conditions through the rest of the week and into next
  weekend, but a low risk for some spotty light precip at times near
  the coast Wed and Wed night

* Cold with below normal temps Wed, then slowly moderating temps for
  the rest of the week into next weekend

* Potential for unsettled weather late Sun and/or next Mon

Details...

Tuesday night into Wednesday night...

Strong shortwave moves east from Maine developing into a closed Low
south of Nova Scotia which will bring a surge of low level colder
air southward into SNE with 925 mb temps dropping to -6 to -8C. Lows
Tue night will drop into the teens and low 20s with highs Christmas
Day upper 20s to mid 30s. The column also dries out considerably
with PWATs dropping to around 0.10". So overall a dry period with
clearing skies Tue night and lots of sunshine Wed. However, low
level northerly flow and shallow low level moisture may result in
considerable cloud cover over the Cape/Islands and coastal SE MA
through Wed night and can`t rule out spotty ocean effect snow
showers. But given dry air aloft and potential for snow growth
region to dry out, there is some risk for patchy drizzle or freezing
drizzle. Both GEFS and EPS ensembles show high probs (60-90%) of QPF
> 0.01" through Wed night over Cape Cod.

Thursday through Sunday...

Mid level ridging gradually builds over New Eng, especially this
weekend before moving to the east toward the end of the weekend.
Meanwhile, strong high pres sets up over Quebec Thu-Fri before
shifting to the Maritimes next weekend. The column remains dry with
persistent N-NE flow so will have to watch for more cloud cover near
the coast, otherwise dry weather prevails into Sunday. However, as
mid level ridge moves to the east Sunday, next system will be
approaching from the west. Still lots of uncertainty with respect to
the timing and amplitude of next approaching trough and shortwave.
ECMWF and CMC have a more amplified system with some of its
ensembles bringing in precip as early as Sunday while GFS and its
ensembles are weaker and drier. Thermal profiles look to be warm
enough aloft for rain or some interior ice at the onset if low level
cold air is slow to erode. Temps will gradually moderate through the
period, from 30s on Thu-Fri with some 40s by the weekend in the
coastal plain and valleys.

&&

.AVIATION /18Z MONDAY THROUGH FRIDAY/...
Forecast Confidence Levels:

Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.

18z TAF Update...Moderate confidence, mainly for tonight and Tue
morning.

Areas of MVFR ceilings in southeast MA should clip BOS for a few
hours until late afternoon as flurries come to an end near Cape
Cod. Otherwise VFR conditions give way to lowering ceilings
later tonight with spotty areas of -SN and localized MVFR
visibilities, especially in RI and eastern MA.

Steadier area of -SN arrives in western MA and CT toward sunrise
but may fragment as it reaches BOS/PVD and points SE Tue
morning. Nonetheless, MVFR or lower-end VFR ceilings prevail
through midday Tue before improvement to VFR Tue afternoon and
Tue night, but bands of ocean effect clouds could bring MVFR
ceilings near Cape Cod and the islands and just offshore.

Light SW winds increase to 10-15kt Tue morning, then shift to NW
Tue afternoon and become more N Tue night.
kt.

KBOS TAF...Moderate confidence in TAF. Fairly certain on -SN
timing Tue but it`s possible vsby lowers to 4-5SM for a time.

KBDL TAF...High confidence in TAF.

Outlook /Tuesday Night through Friday/...

Tuesday Night through Christmas Day: VFR. Breezy.

Wednesday Night through Friday: VFR.

&&

.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.

Updated: 3:30 AM

Today and Tuesday...High confidence.

Cold and quiet through late afternoon, light northerly wind
becomes southwest this evening as an Arctic high pressure
system moves across the waters. Seas between 2 and 4 feet.

Tonight into Tuesday a weak clipper system moves across
northern New England, increasing southwest wind ahead of a cold
front on Tuesday leads to gusts of 20 knots. Cold front pushes
east of the waters Tuesday afternoon with light rain and snow
showers. Seas build slightly on the outermost southern waters,
but do remain below advisory criteria.

Outlook /Tuesday Night through Friday/...

Tuesday: Winds less than 25 kt. Seas locally approaching 5 ft.
Chance of rain.

Tuesday Night: Winds less than 25 kt. Areas of seas approaching
5 ft.

Christmas Day: Winds less than 25 kt. Local rough seas. Chance
of rain showers, chance of snow showers.

Wednesday Night: Winds less than 25 kt. Local rough seas.
Slight chance of rain showers.

Thursday through Friday: Winds less than 25 kt. Local rough
seas.

&&

.CLIMATE...
Record Lowest Minimum Temperature: 12/23

BOS: -12F (1883)
BDL:  -5F (1989)
PVD:   2F (1989)
ORH:  -2F (1989)

&&

.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.

&&

$$

SYNOPSIS...KJC/Dooley
NEAR TERM...JWD
SHORT TERM...Dooley
LONG TERM...KJC
AVIATION...JWD
MARINE...KJC/Dooley
CLIMATE...Dooley