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407
FXUS61 KGYX 151032 RRA
AFDGYX

Area Forecast Discussion
National Weather Service Gray ME
630 AM EDT Wed May 15 2024

.SYNOPSIS...
A stalled frontal boundary will result in unsettled, showery
weather for the remainder of this week and through the weekend
with temperatures remaining seasonable for mid May. A few
thunderstorms are possible this afternoon, mainly across
northern areas.

&&

.NEAR TERM /TODAY/...

-- Changed Discussion --
630 AM Update...Minor edits to sky, temps, and dewpoints to match
observations, but the overall forecast remains on track.

Previous...

The unsettled pattern continues today with a stalled frontal
boundary lingering across the area and weak forcing aloft bring more
showers to the area along with a chance thunderstorms across
northern areas this afternoon. In the low levels, a weak ridge
axis will be draped across the area with a light southwesterly
flow while a low- pressure system emerges off the Mid-Atlantic.
This will bring another warm day with temperatures expected to
reach the upper 60s to lower 70s across the interior while the
coast again remains a tad cooler.

Back to rain chances...expect a few showers to continue across
northern areas early this morning with weak PVA aloft. Looking
upstream...an area of (mostly) light showers is pushing into western
Mass. at this hour, and expect this to gradually move northward
across southern and central NH this morning. Short-range
guidance depicts this area of light showers will gradually
dissipate by late morning or early afternoon, but it`s possible
a few additional showers redevelop across these areas after.

Central and northern areas continue to be favored for showers
and a few storms this afternoon while areas to the south see
lesser coverage. Flow aloft will be very weak, so showers/storms
will be slow-moving, and due to the slow-moving nature, hydro
concerns aren`t out of the question across the north today if
repeated rounds or more persistent convection occurs,
especially with moisture being a bit higher than yesterday.
-- End Changed Discussion --

&&

.SHORT TERM /TONIGHT THROUGH THURSDAY/...
Convective coverage will follow a downward trend this evening
with potential for any thunder only lasting maybe an hour or two
after sunset. There will still be some lift present from the
foothills northward overnight however, so I still think there
will be showers from time to time, especially farther north. The
rest of the area is expected to remain generally dry, with the
exception being southern NH where some light rain may sneak on
the northern fringe of the area of low pressure to the south.
Otherwise, light winds and sufficient boundary layer moisture
will again promote fog development with most of western ME and
into northern NH looking the best potential. The Midcoast may
even start seeing marine fog move in as early as late this
evening. Overnight lows remain above normal with temps staying
the 50s.

Slow-moving low pressure will still be meandering well to our south
on Thursday while a weak 500mb ridge tries to nose into northern New
England. There will still be enough moisture/weak instability for
diurnal showers, again with central and northern areas favored,
but I think coverage will be kept on the lower side given that
the atmosphere will be slightly drier and also with some
suppression from the ridge. That said, there is little to no
flow aloft, so what does develop will probably be slow-moving
and could bring some heavy downpours. Max temps across the
interior look to be mostly in the lower 70s while the onshore
flow limits temps along the coast to the 60s.


&&

.LONG TERM /THURSDAY NIGHT THROUGH TUESDAY/...
A largely unsettled pattern persists over the area with
fuzzy day-to- day details, but a straight-forward broad picture
featuring daily chances for mainly-diurnal showers and predominantly
mild conditions. From a synoptic standpoint, this is due to
predominantly zonal flow over the NOAM mid-latitudes featuring a
conga line of northern and southern stream disturbances embedded
within the westerlies.
At the surface, there is good model agreement keeping high pressure
centered over Maritime Canada... and extending south along the New
England Coast. The combination of the two gives neither a total-
washout of an extended forecast, nor a dry stretch of weather... but
somewhere in between.

From a hazard perspective, slow-moving/stalled fronts with
disturbances running along them will promote potential for back-
building and/or training showers and some thunderstorms.

This flow regime also promotes periods of onshore flow. Much like
the last several days however a source region from the Maritime
Canada high may not be humid enough to produce classic "socked in"
conditions along the coastal plain. Early looks at boundary layer
lapse rates suggests as much. So ultimately it looks like we`ll
enjoy nicer weather than surface wind direction may otherwise imply
with temperatures generally warming into the 60s and 70s... modified
by afternoon showers and storms, and by the sea breeze. Ensemble
solutions suggest the greatest inroads for the marine layer comes
this weekend, with the aforementioned southern stream Atlantic low
potentially drifting north and bringing some of its moisture into
the easterly flow across the Gulf of Maine. Although humid, PoP has
actually trended down around that time given a lack of adequate
phasing and forcing.

&&

.AVIATION /08Z WEDNESDAY THROUGH SUNDAY/...
Short Term...Fog will remain a threat through around 12Z this
morning, especially from HIE-AUG-PWM-RKD, and conditions could
drop to IFR to LIFR at times, but there should be steady
improvement beyond 12Z. Another area to watch will be an area of
light rain showers and MVFR conditions tracking across southern
NH today. Mainly VFR outside of precipitation the rest of
today, with scattered showers again potentially bringing
restrictions should they pass over any terminal. Highest
potential for this will be north of a LEB- IZG- AUG line, where
there may also be a few thunderstorms. Coverage of showers will
diminish this evening with only a low chance overnight, but fog
and low ceilings will be a threat again. Overall coverage of
showers looks lower on Thursday with generally VFR outside of
showers.

Long Term...Low confidence in the day to day details of the forecast
exists, especially along the coast. However the pattern suggests
prevailing VFR with potential for periodic restrictions in overnight
FG or afternoon/evening SHRA.

&&

.MARINE...
Short Term...Weak surface ridge will be draped across the waters
today into tonight with a prevailing light south to southwest flow.
At the same time a slow-moving low pressure will remain nearly
stationary off the Mid-Atlantic coast, and while it will stay well
south of the waters, it will weaken the surface ridge and bring a
light easterly flow over the waters on Thursday. Fog will become
more likely tonight and Thursday.

Long Term...Weak pressure gradient force keeps winds and seas below
SCA thresholds through the long range forecast period. The best
chance for any sort of active seas comes with a swell off a distant
Atlantic storm system, which may approach 5 ft over the weekend.

&&

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

&&

$$


NEAR TERM...Combs
SHORT TERM...Combs
LONG TERM...Casey