Marlborough, New Hampshire Weather Forecast Discussion

294
FXUS61 KBOX 041135
AFDBOX
Area Forecast Discussion
National Weather Service Boston/Norton MA
735 AM EDT Sat Oct 4 2025
.SYNOPSIS...
High pressure to our southeast maintains dry weather, with well
above normal temperatures today through early next week. Then a
cold front moves through Southern New England Tuesday night
into Wednesday, bringing some much needed rainfall. Much
cooler/drier weather follows for Thursday and Friday with
temperatures averaging a bit below normal.
&&
.NEAR TERM /THROUGH TONIGHT/...
230 AM Update:
Key Messages:
* Sunny, unseasonably warm with highs in the low to mid 80s.
* Seabreezes keeps eastern/southern coasts slightly cooler.
Details:
Surface high pressure and building 500 mb geopotential heights
characterize the governing large-scale pattern early this morning
across Southern New England. The building 500 mb heights in midlevel
WNW flow aloft are associated with an amplified mid/upper level
ridge over the Southern Plains region, with unseasonably warm air by
early-October standards accompanying it. Temperatures early this
morning are running some 10-15 degrees warmer than the past few
nights, with readings in the mid 40s to mid 50s for the interior,
and upper 50s to around 60 due to a continued SW breeze for eastern
MA and RI.
An anticipated multi-day stretch of well above normal
temperatures begins today, spanning into early next week. Full
sunshine today combines with warming 925 mb temps to around
+17-19C and an added boost from the drying topsoils to push
highs in many areas away from the coasts into the low to mid
80s. These readings look to fall short of daily record highs for
October 4th, which are in the mid/upper 80s for our four
climate stations, but still will be some 15 degrees warmer than
upper 60s normals. The Cape and Islands and along the immediate
southern coast stand to be slightly cooler in the mid 70s due
to a modest SW flow/seabreeze. In addition...the immediate coast
of eastern MA seems likely to get an ESE seabreeze given weak
boundary-layer winds; it could be one of those days where
Boston/Logan Airport is in the lower 70s most of the day but
then gets a late-day spike in temps to near 80 once the
seabreeze turns to a light SWly. Light west winds otherwise,
with RHs around 30 to 45 percent.
&&
.SHORT TERM /SUNDAY/...
230 AM Update:
Key Messages:
* Mostly clear (marine fog possible southern coast/waters) with
  mild lows.
* Remains warm and dry with coastal seabreezes Sun, highs low
  to mid 80s.
Details:
Tonight:
Mostly clear skies and light (tending light northerly) winds for
tonight. Some of the NAM-based/HREF members were offering hints at
patchy marine stratus or fog along the southern coastal waters and
perhaps immediate southern coast with shallow moist-advection but
not likely much impact. Lows in the mid 50s to near 60.
Sunday:
Sunday is essentially a persistence forecast to today; the only
minor change(s) are a better chance at a coastal seabreeze and the
500 mb ridge amplifying. With the warming 925-850 mb temps acting as
a thermal inversion near the coast, if we do get any marine fog or
stratus near the south coast from overnight, it may be slow to
disperse. But otherwise, quite warm and continued dry with highs in
the low to mid 80s away from the coast, and into the mid 70s near
the southern and eastern coasts.
&&
.LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
Key Messages:
* Unseasonably warm temperatures and dry weather thru Tue.
  Increased southerly breezes could lead to fire weather
  concerns Mon and especially on Tue.
* Welcomed rainfall either late Tue night or Wed as a cold front
  moves in. Thunder possible.
* Much cooler, blustery and dry Thu/Fri with highs in the 50s to
  lower 60s; possible frost Thu night.
Details:
Monday and Tuesday:
High pressure to our south then starts to slowly migrate to our
southeastern waters, allowing for a strengthening SWly pressure
gradient to take shape. Above normal temperatures are still expected
on both days, although cloud cover starts to increase later Tue/Tue
night as a strong cold front begins to approach interior western New
England. SWly winds will keep seabreezes from developing; while RH`s
will be running a little higher than we`ve seen recently, the dry
ground combined with the SWly winds could pose concerns for fire
weather on both days, but especially Tue as SWly winds may gust up
to 30 mph. Nighttime lows also could be quite a bit warmer than
climatology too given the SWly winds, and could stay above 60
degrees in several spots.
Wednesday:
A cold front will be moving through Southern New England around Wed;
some question on timing as a few more progressive solutions show
cold frontal rains moving in as soon as Tue night but think Wed is
more likely given the amplified 500 mb pattern (front-parallel mid-
level flow shown in most model systems). This will bring a welcomed
rain and perhaps some timing-dependent t-storms too given advection
of steeper mid-level lapse rates. Ensemble QPF probs seem to have
increased compared to prior cycles, with moderate (40-60%) probs of
rain amts of at least a half inch, and if we do see any t-storms,
then the risk for localized downpours could develop given anomalous
moisture plume (PWATs around 1.5"). Cloudy and cooler highs in the
lower to mid 70s.
Thursday and Friday:
Strong 1030+ mb high pressure then begins to build in for Thurs,
ushering in blustery and well-mixed conditions on Thurs to go along
with cooler temps. 925 mb temps off the GFS are down to the lower
single digits Celsius, which could keep highs in the mid 50s to
lower/mid 60s Thurs, to go along with northerly breezes. A chilly,
frosty Thurs night looks likely away from the coast as winds slacken
and strong cooling takes place. So, late week takes a turn back to
mid-autumn.
&&
.AVIATION /12Z SATURDAY THROUGH WEDNESDAY/...
Forecaster Confidence Levels...
Low - less than 30 percent.
Moderate - 30 to 60 percent.
High - greater than 60 percent.
12z TAF Update:
Through Sunday: High confidence.
VFR through the period. Low chance of patchy stratus/fog along
the south coast and Cape/Islands overnight tonight. Too low in
confidence and coverage to include in TAF.
Westerly winds under 10 kt today, with ESE seabreezes looking
more likely at BOS and at PVD. Winds become light northerly
(calm at times) tonight. Winds Sunday quickly become SWly under
10 kt, with seabreezes for BOS/PVD.
KBOS Terminal...High confidence in TAF. ESE seabreeze likely to
develop around 14-16z. Back light S/SW 22-00z. Seabreezes
anticipated again Sunday.
KBDL Terminal...High confidence in TAF.
Outlook /Sunday Night through Wednesday/...
Sunday through Sunday Night: VFR.
Monday: VFR. Breezy.
Monday Night: VFR.
Tuesday: VFR. Breezy.
Tuesday Night: Mainly VFR, with areas MVFR possible. Breezy.
SHRA likely.
Wednesday: MVFR/IFR conditions possible. Breezy. SHRA likely.
&&
.MARINE...
Forecaster Confidence Levels...
Low - less than 30 percent.
Medium - 30 to 60 percent.
High - greater than 60 percent.
Tranquil boating conditions this weekend, with SW winds around
10 kt and seas below small craft advisory criterion. Low chance
at patchy marine fog over the southern waters tonight.
Outlook /Sunday Night through Wednesday/...
Sunday through Monday Night: Winds less than 25 kt.
Tuesday: Low risk for Small Craft Advisory winds with gusts up
to 25 kt. Seas locally approaching 5 ft.
Tuesday Night: Low risk for Small Craft Advisory winds with
gusts up to 25 kt. Areas of seas approaching 5 ft. Chance of
rain showers.
Wednesday: Winds less than 25 kt. Seas locally approaching
5 ft. Rain showers.
&&
.BOX WATCHES/WARNINGS/ADVISORIES...
CT...None.
MA...None.
RI...None.
MARINE...None.
&&
$$
SYNOPSIS...Loconto
NEAR TERM...Loconto
SHORT TERM...Loconto
LONG TERM...Loconto
AVIATION...Loconto/Mensch
MARINE...Loconto

NWS BOX Office Area Forecast Discussion