069
FXUS61 KGYX 162349
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
749 PM EDT Fri May 16 2025

.SYNOPSIS...
A slow moving low pressure system will bring rounds of showers
and thunderstorms tonight and through the weekend. Storms
through tonight may be slow-moving, potentially leading to
localized flash flooding north of the mountains. Saturday,
storms may be more organized, leading to some stronger storms
across NH as well as a potential flash flooding threat again
north of the mountains.

&&

.NEAR TERM /THROUGH SATURDAY/...
745 PM Update... Weakening thunderstorms are continuing to
slowly push eastward at this hour across north-central NH and
interior western ME. Storm strength has been on a noticeable
decline with the loss of daytime heating and therefore the
threat for gusty winds/hail has ended but locally heavy rainfall
remains possible. Along the Mid- Coast, fog is moving onshore
with KRKD already down to 1/4SM. Will monitor trends to
determine if a dense fog advisory will be needed. Made some
adjustments to PoPs, temperatures, and sky cover but the overall
forecast thinking remains on track.

Previously...
Radar imagery currently shows numerous pulse thunderstorms
across the interior. These storms are producing heavy downpours,
and may have the potential to produce some gusty winds and
small hail as well. Storms are slow moving and there is some
training, so localized flash flooding may occur with some
heavier storms. Coastal areas should stay mostly dry this
evening, as the sea breeze should keep more stable air over the
coast.

After the frontal passage late tonight, marine fog builds back into
the coastal plain. Scattered showers and developing fog overnight
should allow for mild low temperatures tonight, with lows in the 50s
and 60s.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH 6 PM SATURDAY/...
Key Points:

-Rounds of storms tomorrow may bring damaging winds and
 localized flash flooding to New Hampshire and western ME. The
 damaging wind threat looks to be across southwestern New
 Hampshire, while the flooding threat tomorrow is highest from
 the foothills and points north.

-The SPC has issued a Slight Risk for Severe Weather in
 Southwest NH

-The WPC has issued a Slight Risk for a 15% chance of excessive
 rainfall from the foothills and points north.

Details:

Visibility restrictions will be possible through most of the
day tomorrow as very light onshore winds continue to advect fog
into much of western Maine. Fog will keep high temperatures
across Maine lower, and keep the environment more stable. Over
western and southern NH, there should be thinner clouds with
more breaks in them. This will allow for warmer high
temperatures and allow for the environment to destabilize,
becoming more conducive for severe weather.

The environment tomorrow afternoon features 1000-1500J/kg of
CAPE, some wind shear and 100m^2/s^2 of low-level helicity. These
parameters suggest that damaging winds and hail are possible
with thunderstorms across southwestern NH. In addition,
multiple rounds of showers and storms across the north tomorrow
may produce some localized flash flooding as well.

The strongest storms move across western NH in the mid-afternoon,
with another round of storms possible later on in the evening. Fog
over Maine will allow for the marine layer to advect all the way to
the mountains, with most storms weakening as they enter these
areas of fog.

&&

.LONG TERM /SATURDAY NIGHT THROUGH FRIDAY/...
The surface low will exit into Downeast Maine Sunday morning while
the 500 mb crosses overhead through the day. There could be fog and
low stratus lingering in the morning, especially over eastern areas,
but otherwise the upper low will bring another day of high shower
coverage during the day and into Sunday night, especially
inland and toward the mountains with activity more scattered
farther south and closer to the coast. I don`t think there`s
enough instability to include thunderstorms in the forecast at
this point as models are mostly showing on the order of a couple
hundred J/kg of CAPE.

The upper low shifts east of the area early next week to around Nova
Scotia, but broad troughing across the NE and enough residual
moisture will still be sufficient enough for isolated to scattered
showers to develop (lower coverage than Sunday), mainly during the
daytime hours. Temperatures will be in the mid 50s to lower 60s for
the most part on Monday and then a touch cooler on Tuesday.

Another slow-moving, upper low then enters the picture for the
second half of next week with models in good agreement a 500-mb low
closing off near the Great Lakes that will slowly head toward New
England. Shower chances will ramp back up as a result with cloudier
conditions and temperatures staying on the cooler side.

&&

.AVIATION /00Z SATURDAY THROUGH WEDNESDAY/...
Short Term...

Thunderstorms and fog will keep restrictions mostly down this
evening, likely continuing through Saturday and Saturday night as
fog and multiple rounds of showers and storms move across NH
and ME.


Long Term...LIFR to IFR fog and/or stratus may stick around
12-15Z Sunday, mainly in the RKD-AUG corridor...otherwise
showers will again be likely during the day Sunday into Sunday
and could produce IFR to MVFR conditions. For Monday and
Tuesday...MVFR ceilings possible during the first part of
Monday, but coverage of showers will be lower and mostly during
the daytime hours these days. Chances for showers and and flight
restrictions then increase toward the middle of next week.

&&

.MARINE...
Short Term...

2-4ft seas expected this evening through Sunday morning. This
afternoon, winds will be southerly at 6-11kts. Winds strengthen to 8-
13kts Saturday morning ahead of a frontal boundary. The frontal
boundary crosses the waters tomorrow night, with winds shifting to
westerlies at 6-11kts by Sunday morning.

Long Term...Winds become westerly Sunday and then northwesterly Monday into
Tuesday as surface low pressure moves east of the waters. Gusts to
20-25 kt may occur from time to time during this period, but in
general things look to remain under SCA levels through Wednesday.
Winds become east to northeast toward the second half of next week
with developing low pressure to the south. It`s uncertain what track
the low will take, but SCA conditions are possible toward late
week.

&&

.HYDROLOGY...
Torrential downpours with rain rates as high as 1-3" per hour
from slow-moving showers and storms will pose a risk of flash
flooding through this evening, mainly from the mountains
northward. Multiple rounds of showers and storms are again possible
during the day Saturday and could pose another threat of flash
flooding. The threat is highest from the foothills and points
north on Saturday where WPC has highlighted a Slight Risk of
Excessive Rainfall.

&&

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

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Palmer
LONG TERM...Combs