133
FXUS61 KGYX 280659
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
259 AM EDT Tue Jul 28 2026

.WHAT HAS CHANGED...
No significant changes with this update with the main focus
being a return to wet weather starting today and lasting through
the work week.

&&

.KEY MESSAGES...
1. The recent dry stretch of weather ends today with increasing
chances for slow moving showers and thunderstorms by Tuesday
afternoon and evening.

2. A cut-off low develops over the region Tuesday night and
Wednesday and remains in the vicinity through Friday.  This will
bring multiple rounds of rainfall with locally heavy rainfall
possible.

3. Some periods of drier weather this weekend with warmer
temperatures, but daily chances for precipitation continue,
especially Sunday.

&&

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

Today opens with a large trough over Hudson Bay with shortwaves
rotating around this feature. A robust shortwave will reach the
eastern Great Lakes by this morning helping to close off a H5
low by this evening over upstate New York. The result will be
building southerly flow to the east of this feature with 1.5"
PWAT plume pushing east into NH and far western ME by Tuesday
night. Mid level forcing lags that moisture plume so expect best
potential for afternoon/evening storms to be over NH. The CAMs
show a decent setup for locally heavy rain with narrow CAPE
profiles, MBE vectors with less than 10kts net storm motion and
deep warm cloud depths in the presence of PWATs locally over
1.75". Current depictions show a decent storm motion given that
the llevel jet is not all that strong and only
isolated/scattered coverage...so...while there are some
ingredients for flash flood potential...agree with the previous
shift that given such dry antecedent conditions this event will
likely only serve as a primer for the larger event on Wednesday.
Cannot rule out an isolated instance of flash flooding but feel
the overall threat is low. Clouds will be on the increase
through the day with highs cooler than on Monday...close to 80
in most locations.

KEY MESSAGE 2 DESCRIPTION...

Cutoff low slowly moves from upstate NY on Wednesday morning...to
southern New England on Thursday morning to the Gulf of Maine by
Friday morning.  Most impactful weather period is expected to be
Wednesday as surface low should drive a band of moderate to locally
heavy rainfall through the region...with additional rainfall
developing near the low again Thursday.  Given clouds and
precipitation...temperatures will be below normal through the
period.

For Wednesday...the arriving low will strengthen the southeastern
LLJ which may allow for more backbuilding of embedded convective
elements in a precip-efficient environment.  However...instability
looks to be less than the day previous.  The guidance suite has a
decent amount of spread on the exact timing/orientation of the
rainfall...but feel that by late morning and through the afternoon
moderate to locally heavy rainfall is possible and there will be a
threat of isolated flash flooding if training cells can materialize.
While it will be humid...clouds and rainfall will keep temperatures
in check with most locations remaining in the lower 70s...and
perhaps some spots not reaching 70. Showers will likely continue
through Wednesday night with fog also likely given the moist airmass
in place.

Shower activity continues for the day on Thursday though placing the
heaviest/most persistent shower activity is not possible at this
range with a fair amount of spread in the guidance.  With the axis
of the upper low overhead...rainfall activity may be very slow
moving and while the overall column will have cooled a bit...the
threat for flash flooding /now with increasingly saturated soils/
may increase if the activity is organized/widespread enough.  Expect
that as the llevel flow turns more northeasterly Thursday night
that any flooding threat will end but some isolated/scattered
showers will likely continue.

Reviewing the ensemble probabilities...2" probabilities are
generally restricted to far SW ME and NH along/south of the
mountains.  With flash flood guidance well above this /6 hour
guidance over 3" for nearly all of the area and greater than 4" for
the NH mountains...lakes region and SE ME/ it suggests that any
possible flash flooding for the Wednesday-Thursday period will be
isolated.  There is not expected to be any river flooding with this
event with plenty of storage given a much drier than normal July to
date so far.

The cutoff low finally opens up Friday and begins to pull east which
should allow more sunshine...and warmer temperatures though the
threat for scattered showers will continue.

KEY MESSAGE 3 DESCRIPTION...

Global models are in surprisingly good agreement on the 500 mb
pattern going into next week. Low pressure finally loses its grip on
the region by Saturday while essentially dissipating offshore.
Should note there is still some split guidance on how quickly this
happens, and given cutoff lows are generally not handed well by
global guidance, still a bit uncertain how fast this happens.
Regardless, most guidance keeps Saturday on the dry side, with some
subsidence behind the coastal low likely playing a role.

Sunday onward may be a different story, as guidance suggests the
Hudson Bay upper-level low reorganizes, lifting another 500 mb
trough towards New England by Sunday night, with subtle height
falls. With southwest flow ahead of this feature developing, as well
as a possible surface low somewhere in the Ohio Valley, signs are it
will turn humid and possibly rainy once again, although that is
about the most we can say with confidence six days out. So in a
nutshell, Saturday is likely the drier of the two days, while Sunday
brings increasing chances for showers late, especially across the
interior.

&&

.AVIATION /06Z TUESDAY THROUGH SATURDAY/...

Through tonight...

Summary: Increasing moisture will bring some potential for low
clouds and fog towards daybreak today with shower and
thunderstorm chances increasing this afternoon and evening for
NH terminals. Low cigs and patchy fog are likely tonight with
chances for showers

Restrictions: Mainly VFR. Increasing moisture will clouds to
thicken and lower across NH and coastal Maine. The remains
potential for IFR in fog and CIGs for LEB/HIE. Conditions
should improve to VFR at least for a time by mid/late morning
and into the afternoon before restrictions are again possible
this afternoon and evening due to SHRA/TSRA primarily for NH
terminals. IFR to LIFR is likely across all site in low cigs and
visibility restrictions in fog.

Winds: Light winds through day break will strengthen again to
10-15kts late morning...diminishing to less than 10kts tonight.

LLWS: No LLWS is expected through the TAF period and through Tuesday
night.

Thunder: Isolated to scattered slow moving /movement generally
from south to north/ thunderstorms are possible this afternoon
and evening, particularly for NH terminals.


Outlook:

Wednesday - Thursday: Slow moving low pressure will bring multiple
rounds of rainfall to the region with a prolonged period of IFR/MVFR
restrictions. Winds at or below 10kts.

Friday - Saturday:  Expect conditions to slowly improve on Friday as
low pressure moves away from the region though scattered showers and
a thunderstorm are possible.  VFR conditions should dominate
Saturday outside of an isolated afternoon shower/storm. Winds at
or below 10kts.

&&

.MARINE...
Conditions remain below SCA levels through at least the first half
of Wednesday...though there will be increasing potential for fog
over the waters by late tonight and continuing through much of the
week.  Low pressure passing south of the region Wednesday night and
Thursday will bring strengthening easterly winds and building wave
heights with SCAs likely necessary Wednesday afternoon and
continuing through Thursday.  Improving conditions arrive to end the
week Friday and persist through the weekend.

&&

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

&&

$$

DISCUSSION...Arnott/Barker/Schroeter