551
FXUS61 KGYX 182257
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
657 PM EDT Sat May 18 2024

.SYNOPSIS...
A cold front moves offshore through the evening hours. High
pressure strengthens over the region and just offshore early
next week with dry conditions and well above normal
temperatures. Scattered showers return by late Wednesday into
Thursday as a cold front approaches and then crosses the region.
An upper level trough will keep scattered showers over the
region Friday. High pressure builds in from the north next
weekend, bringing a return to cooler conditions.

&&

.NEAR TERM /THROUGH SUNDAY/...
700 PM Update... Main area of light stratiform rain in
association with an h7 shortwave trough and associated moisture
convergence continues to stream northeastward over western ME
south of the mountains as well as southeastern NH. Latest hi-res
guidance and radar trajectories indicate this trend will
continue through this evening with just a few light showers or
perhaps drizzle persisting overnight, along with fog. Other than
sharpening up PoPs to capture latest radar trends and loading in
the latest sfc observations, no significant changes were made
to the inherited forecast.

Previously...
Impacts:
*No significant weather impacts expected

A decent area of rain has moved into southern New Hampshire and
is expected to move northeastward hugging the coast and
interior zones of Maine through the evening. More scattered
showers continue to move northward through northern zones at
this hour and are expected to clear out late this evening.
Additional showers may also come ashore in both Maine and New
Hampshire before the upper and surface low fully move out of the
region. Therefore kept likely PoPs on the coast through
midnight to account for these lingering showers, but they will
taper off quickly. Visible satellite imagery shows the clearing
line behind this shortwave is just about getting into Vermont at
this hour and may begin to reach northern and western New
Hampshire after midnight. Still, clouds will keep temperatures
in the lower 50s with those areas that see some clearing
standing the best chance of dipping a bit cooler. Patchy fog
will be much more widespread tonight, with locally dense patches
likely especially in areas that saw decent rainfall.

&&

.SHORT TERM /SUNDAY NIGHT/...
Impacts:
* No significant weather impacts expected

Surface high pressure builds into the region Sunday which will
keep us dry and kick start our warming trend. As clouds
gradually clear from northwest to southeast we could end up with
about a 10 degree temperature gradient between the Connecticut
River Valley and the coast. Currently it looks like western
zones warm into the low to mid 70s while the interior of Maine
and New Hampshire top out in the mid to upper 60s. The coast of
course stays the coolest, only reaching the lower 60s.

Sunday night looks cooler as skies remain partly cloudy. More
areas stand a chance to drop into the mid to upper 40s. We will
be drying out the lower levels as flow turns northwesterly under
the ridge, so would expect fog to be very limited if it even
develops at all. Confidence is low so it has been excluded from
the forecast at this time.

&&

.LONG TERM /MONDAY THROUGH SATURDAY/...
Overview... Heat makes its season debut this week as a ridge
builds across the Eastern US. Temps gradually rise through
midweek, and then humidity begins to increase late in the week
ahead of a cold front. The front likely arrives sometime late in
the week or early next weekend, but uncertainty remains on the
arrival timeframe of this slowing front in the presence of the
ridge.

Details...

This week will be dominated by a warm and summer-like weather
pattern. In the presence of anomalously low pressure across
much of the US and the Central Atlantic, an area of high
pressure develops off the Eastern Seaboard. This sets up an
increasing southerly flow by the beginning of the week, which
gradually turns more southwesterly by midweek. Mostly sunny
skies are expected for the duration of this timeframe, but some
isolated mountain showers are possible across the mountains
early and mid week in the afternoon.

Temperatures gradually rise each day from Monday through
Wednesday. 70s to low 80s are expected inland, while the
coastline remains in the 60s with increasing southeasterly flow.
By Tuesday, a warmer airmass continues to stream in, with winds
becoming more southerly. This sends most areas away from the
immediate coastline into the 80s, with upper 80s expected across
southern New Hampshire. The coastline likely holds onto onshore
flow most of the day, with temps in the 60s along the MidCoast,
to low 70s along the southern coastline. Wednesday looks to be
the warmest day, with south- southwesterly flow pushing the heat
to the southern coastline. 80s are expected in most spots, with
temps near 90 degrees across southern and western New
Hampshire. The MidCoast will be a notable exception, with temps
holding in the 60s with onshore flow continuing. Humidity will
generally be low through this time frame, with dew points mainly
in the 50s. This actually is dry enough to help shave a few
degrees off the heat indices from the air temps.

By Thursday and Friday, humidity begins to increase as a cold
front approaches and helps draw up some moisture from the south.
There remains uncertainty on the timing of this front amongst
the ensembles. While the current forecast holds with NBM dew
points, there is likely to be a period of time where dew points
surge into the upper 60s ahead of the front late in the week.
Temps look to be trending downward during this time frame as
more clouds and showers arrive. Showers and storms are expected
to accompany the cold front when it arrives, but with the timing
uncertainty POPs remain in the chance to low likely range
during this timeframe. By next weekend, cooler air is expected
to arrive as high pressure builds in from the north.

&&

.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
Short Term...A mix of MVFR and VFR ceilings will continue in
the evening before widespread fog develops tonight trending most
terminals toward IFR. Fog will dissipate Sunday morning and
ceilings will have been lifting and clearing out overnight, so
conditions should be VFR early on and remain there through
Sunday night. Winds remain light through the period.

Long Term...Mainly VFR conditions are expected at most
terminals from Monday through Thursday, but some coastal fog is
possible at times at RKD Wednesday and Thursday. Showers and
some thunderstorms bring brief restrictions on Thursday and
Friday, especially to northern terminals. VFR conditions likely
return by next weekend.

&&

.MARINE...
Short Term...SCA seas look to continue through the first part
of Sunday morning as slow moving low pressure passes east of the
waters. Seas look to calm below SCA thresholds through the day
and remain below through the night as high pressure begins to
build over the waters. Northeasterly winds remain 10-15 kts
through Sunday becoming, much calmer into Monday.

Long Term...High pressure builds across the Eastern Seaboard
this week, bringing increasing south to southwesterly flow.
Areas of dense marine fog possible by midweek. SCA conditions
are possible by Thursday with increasing southwesterly flow
ahead of an approaching cold front.

&&

.GYX WATCHES/WARNINGS/ADVISORIES...
ME...None.
NH...None.
MARINE...Small Craft Advisory until 10 AM EDT Sunday for ANZ150-152-154.

&&

$$

NEAR TERM...Tubbs
SHORT TERM...Baron
LONG TERM...Clair