Swanzey, New Hampshire 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

359
FXUS61 KGYX 260619
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
219 AM EDT Sun Jul 26 2026

.WHAT HAS CHANGED...
No significant changes to the going forecast at this time
although there still remains some uncertainty in rainfall
amounts and timing of heaviest rainfall midweek.

&&

.KEY MESSAGES...
1. Pleasant weather continues through Monday under high
pressure.

2. Quiet weather comes to an end with unsettled weather
returning for midweek with the potential for periods of heavy
rainfall and low probability of localized flash flooding.

&&

.DISCUSSION...
KEY MESSAGE 1 DESCRIPTION...

Quiet weather will continue today and Monday with areas of
morning valley and coastal fog. Temperatures will remain near
seasonable normals. The seabreeze will keep the coast cool
during the afternoons. There is a non-zero chance of a few
showers or thunderstorms later Monday afternoon and evening
across western NH and the western ME mountains. However it
appears that the forcing for ascent associated with an
approaching short wave trough will remain far enough west to
keep the area mostly dry.

KEY MESSAGE 2 DESCRIPTION...

It is becoming clear next week will turn wet, especially from
Wednesday onward. A broad upper-level trough will sit over Hudson
Bay. Coming into focus is the likelihood of a cutoff low pressure
stalling and occluding over the Northeast, bringing at minimum a
chance for showers and cloud cover for much of next week, but also
the potential for locally heavy rainfall coming in a few separate
waves.

The GFS/GEPS has joined the Euro and its ensembles in supporting a
more amplified and less progressive low pressure system. However
spread still remains, with the GFS members clustered over coastal
New England, while the Euro members are further north into the
interior Northeast. PWATs, while not the most excessive, rise to
1.50-1.75", which combined with dew points in the 60s, as well as
pretty strong dynamics (many members deepen this surface low below
1000 mb), the stage will be set for plenty of heavy downpours. It is
unclear how much of this precipitation will be stratiform or
convective, but noting some MUCAPE on guidance, which would be most
likely during the afternoon hours each day if any surface heating
can occur.

The ECMWF ensemble is the most bullish on QPF, while the other
members focus the highest totals to our south. As a result, the
current NBM spread is very large. The 50th percentile has 1.00-1.75"
across the forecast area, however the 90th percentile indicates 2.50-
4.00". This is a robust signal at this timeframe and indicates a
high "tail" to the QPF distribution. However, keep in mind this
represents three to four day totals, so while locally heavy rainfall
is possible, not overly concerned about short-fused flash flooding
at this time. July has been anomalously dry for some with minor-
moderate drought conditions still persisting, so a wet week is
generally good news, as long as the rainfall is not overly excessive.

Despite the increasing humidity, daytime temperatures will likely
trend on the cool side, given the increased cloud cover and lowering
500 mb heights/thickness values by midweek. This would be especially
likely if a more southern low pressure track becomes probable.

&&

.AVIATION /06Z SUNDAY THROUGH FRIDAY/...
Through Monday... VFR conditions will prevail through Monday.
The exceptions are at KLEB and KHIE and perhaps KRKD where fog
is once again possible, especially between 09Z-12Z this morning.
SSE winds will persist through Monday at 5-15 kts.

Outlook...

Tuesday-Friday: This period is a bit uncertain, but MVFR
conditions are likely to be most common as low pressure lingers
overhead or somewhere close by. This is expected to bring
widespread rain showers. Fog would likely develop overnight in
the wake of rain showers bringing possible IFR restrictions.

&&

.MARINE...
Winds and seas will remain below SCA criteria through tonight
as high pressure remains near or over the Gulf of Maine.

Generally sub-SCA conditions should start the week, but as low
pressure moves into the region toward midweek chances of 25kt+
winds gusts are going to increase. Wave heights are more likely
to reach or exceed 5 feet late week as the aforementioned low
pressure moves over the waters.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...None.

&&

$$

DISCUSSION...Barker/Ekster