Area Forecast Discussion
Issued by NWS Portland, ME

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894
FXUS61 KGYX 251812
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
212 PM EDT Sat May 25 2024

.SYNOPSIS...
A frontal system brings chances for showers late tonight. A
more organized system approaches for early next week bringing
better chances for widespread showers Monday night into Tuesday.
An upper level trough crosses the region Wednesday through
Friday with more scattered showers and near seasonable
temperatures.

&&

.NEAR TERM /UNTIL 6 AM SUNDAY/...
High clouds will continue over the region this evening as a weak
front approaches from the west. The latest HREF scenario has mid
and low level moisture arriving overnight as well. Scattered
showers may occur mainly after midnight as a weak short wave
approaches from the west within a weak warm air advection
pattern.

The cloud cover with allow for milder temperatures than last
night. Mins will drop into the 40s across portions of the north
with 50s elsewhere.

&&

.SHORT TERM /6 AM SUNDAY THROUGH SUNDAY NIGHT/...
Similar conditions will continue with scattered showers within a
weak warm air advection pattern and a weak trough beginning to
exit to our east. Cool temperatures will continue along the
coastline due to onshore winds. However, some sunshine and ample
mixing will allow for temperatures to climb into the 70s to
lower 80s across the interior. This will sufficiently
destabilize the atmosphere to trigger a few thunderstorms to
develop. The warm temperatures over the holiday weekend will
necessitate an SPS and CFW messages for the inland lakes/rivers
as well as the coastal waters for Sunday.

As the atmosphere stabilizes after sunset Saturday evening, the
chances for precipitation will lower with time. Plenty of clouds
will linger, keeping min temperatures in the upper 40s and 50s
from north to south.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Overview: A return to a more unsettled pattern is in store for much
of next week as a series of fronts associated with upper level lows
cross over Northern New England. Temperatures will generally be
near climatological averages.

Impacts: Moderate to locally heavy rainfall is possible late
Monday and Monday night as deep southerly flow interacts with an
advancing warm front. The greatest potential for heavy rainfall
will be across the mountains.

Forecast Details: An h5 ridge axis will exit to our east on Monday
ahead of a vertically stacked low pressure system that will be
moving over the Great Lakes. Skies will be partly to mostly cloudy
with an increasing chance for a scattered shower during the
afternoon. Highs will generally be into the 60s over
southwestern ME due to onshore flow while southern and western
NH warms into the lower 70s. Low pressure will cross into
southern Quebec on Monday night, sending a sfc warm front
northward over Northern New England. Deep sub-tropical southerly
flow will help to push precipitable water values up to around
1.50", with NAEFS standardized anomalies approaching +2 to +3
standard deviations. This combined with forcing from the front
could result in moderate to locally heavy rainfall overnight,
especially over southeasterly facing higher terrain due to
upslope flow. Lows will primarily be into the 50s to lower 60s.

There remains differences amongst global and ensemble based
guidance on the timing of a trailing cold front, with the ECMWF
favoring a slower arrival and thus more prolonged period of
rain into part of Tuesday while the GFS is has the front
crossing earlier in the day. Nevertheless, would expect at least
scattered showers through part of the day with highs into the
70s to lower 80s depending on how much clearing can be achieved.
Drier conditions are then likely Tuesday night with lows into
the 50s. Another front then may cross on Wednesday, possibly
resulting in additional scattered showers... especially during
the afternoon due to daytime instability. A weak area of low
pressure may then develop along this front into Thursday, with
scattered showers possible along with cooler high temperatures.
High pressure then looks to build to our west Friday through the
first half of next weekend but stalled low pressure near Nova
scotia will result in northeasterly flow and seasonably cool
temperatures.

&&

.AVIATION /16Z SATURDAY THROUGH WEDNESDAY/...
Short Term...Overnight will see thickening and lowering of
clouds, but remaining VFR with a few patches of MVFR ceilings.
Only a chance showers overnight with perhaps some isolated
thunderstorm passing through. Another round of scattered showers
possible Sunday afternoon, with thunderstorms possible in
southern NH terminals.

Long Term...Periods of -SHRA could result in localized
restrictions late Monday before more widespread -RA develops
Monday night into early Tuesday with MVFR to IFR restrictions
possible at times. Mainly VFR is then likely later Tuesday
through the middle of next week, although patchy FG may develop
at night. Winds will primarily be out of the south-southeast
with gusts nearing 20 kts.

&&

.MARINE...
Short Term...A passing weak front tonight will stall south of
the waters, and this may focus shower and possibly a thunderstorm
Sunday afternoon for the area. Conditions remain below SCA, but
storms Sunday could possibly bring small hail or gusty winds to
the southern waters.

Long Term...South easterly wind gusts could approach 25-30 kts
Monday night into Tuesday with seas of 4-6 ft across the outer
waters and 1-3 ft in the bays. Winds and seas will then decrease
towards mid-week behind a cold front.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...Beach Hazards Statement until 8 PM EDT this evening for
     MEZ023>028.
NH...Beach Hazards Statement until 8 PM EDT this evening for NHZ014.
MARINE...None.

&&

$$
NEAR/SHORT TERM...Cannon
LONG TERM...Tubbs