549
FXUS61 KGYX 291805
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
205 PM EDT Wed Jul 29 2026

.WHAT HAS CHANGED...
The Flood Watch for flash flooding has been expanded to include
all of south-central NH.

&&

.KEY MESSAGES...
1. A cutoff low will bring moderate to heavy rainfall through
Thursday across southern areas, resulting in isolated to
scattered flash flooding, especially in southwestern New
Hampshire.

2. The cutoff low is slow to depart on Friday, with gradually
improving conditions through most of the weekend. A semi-unsettled
pattern returns late Sunday and into the next work week.

&&

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

Surface low pressure is currently located across southwestern CT
as of 18Z this afternoon with the associated rain shield
extending northward through southern and central New England.
Rainfall so far has been confined to south-central NH with
amounts up to around an inch across southwestern NE including
the Monadnocks. Latest CAM guidance suggests that this rain
shield will continue its northward trajectory through the
remainder of the afternoon and evening but it should dissipate
some as it moves north of the mountains given that most forcing
for ascent will remain further to the south.

Cutoff low pressure will continue to bring periods of moderate
to locally heavy rainfall through tonight as the SE LLJ
increases, allowing for training of convective showers within a
favorable environment for heavy precipitation. The area of
greatest concern for flash flooding continues to be across
southern NH, particularly in urban areas where there is less
permeable surfaces as well as across the hilly terrain of
southwestern NH including the Monadnocks. Flash flooding is also
possible across the Whites where the SE flow will assist in
upslope precipitation enhancement. Low temperatures tonight will
be into the 50s.

Convective showers will persist through the day on Thursday with
some breaks mixed in between. Given that soils will be saturated
in much of southern NH and portions of southwestern ME, will
need to monitor for any additional heavy rainfall as that may
result in more hydro concerns. Forecast rainfall amounts remain
largely unchanged with generally between 1-3" expected across
south- central NH with the latest 12Z HREF showing the potential
for localized amounts of up to around 5". Rainfall amounts are
then expected to drop off quite rapidly north of the mountains
as well as across much of western ME with some northern
locations likely to receive little to no rainfall. High
temperatures on Thursday will be limited to the upper 60s/lower
70s with lows into the 50s.

KEY MESSAGE 2 DESCRIPTION...

The upper low will be slow to depart on Friday as it moves across
northern New England through the day, gradually meandering east.
This pattern will lead to some isolated/scattered showers,
especially over New Hampshire, the western Maine mountains, and
coastal areas. 12z NAM Nest soundings also suggest that we may have
200 to 500 J/kg of MUCAPE floating around so some rumbles or thunder
are not out of the question. Shear will be weak, so this activity
should be fairly tame. The upper low finally kicks out in the
evening/overnight hours. After a cool Thursday, Friday will start a
warming trend into the weekend with highs expected to mainly range
from the lower 70s north, to the lower 80s south.

An upper level ridge axis will then cross the region on Saturday
which will keep the area mostly dry, but a few isolated mountain
showers/storms will be possible. Temperatures will increase again on
Saturday with the ridge moving overhead, with highs expected to
range from the mid/upper 70s north, to the low/mid 80s elsewhere.

On Sunday, we transition back into southwest flow aloft as the next
trough approaches from the west. This will keep temperatures similar
to Saturday but it could be just a touch cooler as clouds stream
back in. The next chance for widespread rainfall will then move in
Sunday evening, potentially sticking around through Monday
evening/night. As of now, this system doesn`t look to be a prolific
rainmaker with NBM probabilities of a half inch or greater only
maxing out in the 20 to 40 percent range, but most will see at least
some rain with the best chances in the foothill and mountains. After
this system exits, the rest of the week looks fairly quiet with
normal to above normal temperatures.

&&

.AVIATION /18Z WEDNESDAY THROUGH MONDAY/...
Through 18Z Thursday: Periods of RA along with low ceilings will
persist through Thursday, bringing IFR to LIFR restrictions. Fog
is also likely tonight into Thursday morning. Winds will be out
of the SE at 10-15 kts with gusts up to around 25 kts. LLWS is
not anticipated through the period. Winds will become northerly
on Thursday night and diminish to 5-10 kts with gradually
improving flight conditions overnight.

Outlook:

Friday-Sunday: Expect conditions to slowly improve on Friday as low
pressure moves away from the region though a few scattered showers
and a thunderstorm are possible.

Saturday-Sunday: VFR conditions should dominate outside of an
isolated afternoon shower or storm. Winds will mainly be at or below
10 kts.

Sunday night-Monday: Increasing chances for showers and storms may
lead to MVFR/IFR restrictions Sunday evening through Monday.

&&

.MARINE...
East-southeasterly winds will persist through Thursday before
becoming NNE by early Thursday evening while diminishing. A SCA
is in effect for Casco Bay along with the near shore waters
from 03Z Thu through 00Z Fri for ESE wind gusts up to 25 kts
with seas of 3-6 ft.

We remain below SCA criteria through the weekend and into next
week, but we will see increasing onshore winds Sunday afternoon
and into the overnight hours. Southerly winds with gusts up to
20 knots are possible during this timeframe.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...Flood Watch through Thursday morning for NHZ005>015.
MARINE...Small Craft Advisory from 11 PM this evening to 8 PM EDT
     Thursday for ANZ150-152>154.

&&

$$

DISCUSSION...Tubbs/Hargrove
AVIATION...Tubbs