653
FXUS61 KGYX 221018
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
618 AM EDT Mon Jun 22 2026

.WHAT HAS CHANGED...
No major changes needed with this morning update. Just
incorporated the latest observations and freshened up the
aviation section to reflect the 12Z TAF package.

The forecast remains on track. but it is worth noting that some
guidance trended the axis of heavier precipitation further
southeastward in their overnight runs.

&&

.KEY MESSAGES...
1. Soaking rainfall expected this afternoon through tonight.
Some of this rain may be heavy and localized flash flooding is
possible.

2. Temperatures rebound Wednesday and Thursday, but weak
disturbances keep showers possible. A cold front nears the
forecast area Friday.

&&

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

First half of the day is looking okay, but things start
downhill by mid afternoon. Rain will move into the area from the
southwest as a broad area of warm advection precip. Now to
varying degrees CAM guidance is washing this out a bit as it
moves north. There is also some bouncing around of the highest
QPF axis, though you could argue for a subtle southward shift.

What we do know is that this low pressure will be seasonably
strong, something on the order of once a year in early summer.
However the moisture transport is strong, more like once every 5
to 10 years. ECMWF EFI has also highlighted the southern half
of the forecast area for anomalous rainfall totals for this time
of year. That all suggests to me that a widespread soaking rain
is likely, but with higher confidence for areas south of the
mtns. That in and of itself is not a problem, we need the rain
for long term deficits. The hazard will be recent rainfall
coupled with heavy rainfall rates.

21.12z HREF was showing max QPF in the 4 to 5 inch range. The
latest runs of the HRRR have been mimicking those totals,
however bouncing around different points in the forecast area.
Local research has shown that the max QPF totals from CAM
guidance is usually a good guide for what may fall, it is the
location that struggles. So I am on the lookout for those kinds
of high QPF amounts, and if they occur on already saturated
ground from previous day`s rainfall, flash flooding becomes more
likely. Biggest areas of concern there will be the mtns,
especially across western Maine, and into the lower Kennebec
River Valley. There will likely be some thunder with this
rainfall but the threat of severe weather looks to remain
southwest of the forecast area.

Rainfall will clear out pretty quickly Tue morning from west to
east. There may be isolated afternoon showers, but will be
fairly inconsequential compared to the evening and overnight
rains. Given the recent wet weather and high pressure pushing in
Tue night, I expect more valley fog likely.

KEY MESSAGE 2 DESCRIPTION...

Upper trough will be swinging through the Northeast come
Wednesday, with broad cyclonic low level flow overhead. NW flow
remains over the forecast area through the day as this airmass
translates east. It will bring some dry air with it, but think
cloud cover may be a little underdone at this range. Would at
least expect upslope clouds to remain NW of the mountains.
Daytime highs should rebound from a cool start to the week, with
a tight spread on expected highs along the coast and interior.
More variability exists for points NW of the foothills due to
greater cloud cover probability.

Mid level zonal flow continues into late week, and this keeps
the door open for embedded waves to bring short term unsettled
conditions. This may come in the form of diurnal showers
Thursday, before guidance brings a cold front near the region
towards Friday. Current timing isn`t favorable for stronger
storms, but extended machine learning guidance maintains a
signal of possibility for the day.

&&

.AVIATION /12Z MONDAY THROUGH FRIDAY/...
Through 12Z Tuesday...Conditions are returning to VFR as fog
begins to dissipate, and VFR should prevail through at least
18Z. Conditions are expected to deteriorate again this evening
with areas of MVFR or lower ceilings and/or visibilities as
widespread rainfall moves into the region. Conditions should be
able to quickly improve around 12Z Tuesday as the rain begins to
taper off across the area.

Outlook...

Tuesday: Conditions improving to VFR by midday. Isolated shower
possible across the northern half.

Tuesday Night: VFR conditions expected. Patchy valley fog
possible with local IFR or lower.

Wednesday: Mainly VFR with more clouds than sun for the
mountains.

Thursday-Friday: Diurnal showers bring potential for
restrictions Thursday, with a cold front potentially bringing TS
on Friday.

&&

.MARINE...
South southeast winds will increase today ahead of approaching
low pressure. Some marginal SCA conditions are possible across
the waters, especially north of Cape Elizabeth. Winds and seas
will diminish into Tue. The waters remain under cyclonic flow
Wednesday as low pressure pushes into the Canadian Maritimes.
This should result in conditions below SCA criteria through
Friday morning. A cold front will approach the region Friday.

&&

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

&&

$$

UPDATE...Baron
DISCUSSION...Cornwell/Legro
AVIATION...Baron/Cornwell/Legro