923
FXUS61 KBOX 121903
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
303 PM EDT Sat Oct 12 2024
.SYNOPSIS...
Decreasing winds and cold tonight, with lows dropping into
the upper 30s to low 40s. A warm front will bring overcast skies
and scattered light rain showers Sunday and Sunday night. Cold
front moves through Southern New England Monday, bringing
another period of rain showers in the morning, then trending
drier and breezy for the afternoon. Though dry weather will
prevail, blustery with below normal temps are expected Tuesday
and Wednesday, with a gradual warming trend for late in the
week.
&&
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
Gusty NW winds will subside this evening and become light
and variable overnight as the pressure gradient relaxes. With skies
remaining mainly clear tonight, strong radiational cooling
conditions will allow for temperatures to drop quickly into the low
40s, with mid-30s across northern MA.
&&
.SHORT TERM /6 AM SUNDAY MORNING THROUGH SUNDAY NIGHT/...
A weak warm front begins to lift through the region,
which will increase cloudiness in the morning, with complete
overcast conditions by afternoon. Better upper-level forcing from
the shortwave looks to remain north of the MA border. Without
better upper-level forcing, showers will likely be light and more
scattered in nature. Guidance has trended the steadier rain and
higher QPF totals further north. There will be a rather tight
temperature gradient for highs from NW to SE due to the LLJ and
strong warm air advection over SE MA. High temps in SE MA should
reach the low 60s, while temps in NW MA could struggle to even top
50F.
WAA continues overnight, but the upper-level support from the
shortwave continues to remain further west. There is quite a bit of
uncertainty regarding rain chances and intensity as guidance tries
to bring more widespread rain overnight. If rain becomes more
widespread, it will likely remain light except for the Cape and
Islands, where a few hundred J/kg of MUCAPE may be present, allowing
for some convective showers and perhaps a rumble or two of thunder.
The strong temperature gradient continues overnight, with low
temperatures only dropping to the upper 50s to low 60s for the Cape
and Islands, while NW MA could dip into the low 40s to upper 30s.
&&
.LONG TERM /MONDAY THROUGH SATURDAY/...
Highlights:
* Cold frontal passage on Mon. Period of rain early in the day,
trending drier and breezy with cooling temps by afternoon.
Blustery and rather chilly Mon night.
* Generally dry Tue and Wed, but blustery with below normal temps.
Highs in the 40s to low 50s!
* Continued dry for late week but with a gradual warming trend.
Monday:
A pretty strong cold front is forecast to progress across Southern
New England on Monday, although there is still a significant amt of
disagreement regarding its timing as it moves offshore. The U.S.
based modeling systems (NAM, GFS) favor a faster, more progressive
solution which would bring onset of drier weather and post frontal
NW gusts in sooner; the ECWMF and GEM solutions favor cloudiness and
rain showers for a longer timeframe and would delay arrival of drier
weather and increased NW breezes until the afternoon. This will need
to be better resolved in later forecasts but for now I sided the
forecast closer to the slower ECMWF/GEM solutions. Thus official
forecast shows continued lighter rain showers (higher Chance/Low
Likely PoP range) through the morning, then gradually trending drier
W to E for the afternoon. Will show NW cold-advection gusts around
25-30 mph into the aftn, though an earlier cold frontal passage
would translate to an earlier onset of NW gusts. Strong cold
advection post-frontal; 925 mb temps dip to 0 to -2C by 12z Tue per
the GFS. It also looks to remain pretty breezy into the
evening/overnight hours, and while it won`t necessarily feel that
way (e.g. forecast apparent temps around the freezing mark Monday
night!), the breezes will keep air temps in the mid to upper 30s,
though would be around freezing in the hilly terrain.
Tuesday through Wednesday:
Deep midlevel longwave trough establishes itself over the Northeast
states through midweek, associated with a period of below normal 925
mb temps. The main story in this forecast period will be the cooler
and blustery weather, with temperatures running some 10 degrees
colder than normal. Highs topping out only in the 40s to mid 50s and
lows in the 30s (around 30-32 in the high terrain). While generally
dry and mostly clear, ocean effect cloudiness and perhaps an
isolated ocean effect shower or two in coastal southeast New England
with the colder airmass over the milder SSTs.
Thursday and Friday:
Deep longwave trough moves offshore with increasing 500 mb heights
for Thurs and Fri. Dry weather will still prevail into the late week
timeframe, but 925 mb temps steadily rise which will offer a gradual
warming trend.
&&
.AVIATION /19Z SATURDAY THROUGH THURSDAY/...
Forecast Confidence Levels:
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
Rest of today and tonight...High confidence.
VFR. Gusty NW winds to 25-35 kt will gradually diminish this
afternoon and evening, eventually becoming calm tonight.
Sunday...Moderate confidence.
Guidance has trended VFR and drier for much of Sunday. Highest
chance for MVFR will be across northern MA in the middle to late
afternoon. Light rain showers are possible in the late
afternoon mainly north of the MA Pike.
Sunday Night...Moderate confidence
MVFR/IFR with scattered light rain showers continuing.
KBOS TAF...High confidence in TAF.
VFR. Gusty NW winds begin to subside later this afternoon into
the evening. Winds turn to the ESE tomorrow morning. MVFR with
light rain showers possible in the afternoon
KBDL TAF...High confidence in TAF.
VFR. Gusty NW winds begin to subside later this afternoon,
becoming light and variable overnight. Winds turn ESE tomorrow
afternoon with light rain showers possible.
Outlook /Monday through Thursday/...
Columbus Day: Mainly VFR, with local IFR possible. Breezy.
Chance SHRA.
Monday Night through Wednesday: VFR. Breezy.
Wednesday Night through Thursday: VFR.
&&
.MARINE...
Forecaster Confidence Levels:
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tonight through Sunday Night
Winds will quickly subside below 25 knots this evening, eventually
becoming light and turning SSE towards daybreak. 5ft seas in the
outer marine zones should subside to 2-4 ft around midnight. Small
craft conditions become likely again Sunday evening as winds
increase to 25-30 knots from the SSW and seas increase to 4-8 feet,
mainly in the southern waters.
Outlook /Monday through Thursday/...
Columbus Day: Low risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas. Chance of rain showers.
Monday Night: Moderate risk for Small Craft Advisory winds with
gusts up to 30 kt. Areas of rough seas.
Tuesday: Moderate risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft.
Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Seas up to 5 ft. Slight chance of rain
showers.
Wednesday through Wednesday Night: Winds less than 25 kt. Areas
of seas approaching 5 ft. Slight chance of rain showers.
Thursday: Winds less than 25 kt. Seas locally approaching 5 ft.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...Small Craft Advisory until 5 PM EDT this afternoon for
ANZ230>237-251.
Small Craft Advisory until 5 AM EDT Sunday for ANZ250-254.
Small Craft Advisory until 11 PM EDT this evening for ANZ255-
256.
&&
$$
SYNOPSIS...Loconto/KP
NEAR TERM...KP
SHORT TERM...KP
LONG TERM...Loconto
AVIATION...Loconto/KP
MARINE...Loconto/KP
NWS BOX Office Area Forecast Discussion
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