FXUS61 KGYX 210200
Area Forecast Discussion
National Weather Service Gray ME
1000 PM EDT Thu Jul 20 2017
Widely scattered thunderstorms across the region will weaken
quickly after sunset tonight. Temperatures will slowly fall back
into the 60s for most locations. Friday temperatures tick up a
degree or two...as westerly...offshore flow dominates.
Temperatures remain warm into the weekend. A low pressure
system may bring cooler weather and more potential for rainfall
Sunday night into early next week.
.NEAR TERM /UNTIL 6 AM FRIDAY MORNING/...
10 PM...Other than the slight possibility of a breif light SHRA
popping up up over the ern zones thru midnight, where there are
still some sfc boundaries, should be precip-free overnight.
Valley fog is expected, and there could be some light patchy
fog anywhere else, given the higher Tds, but this will be most
likely along the coast.
715 PM...Grids adjusted to account for current convection
/mostly winding down/, and to overall lower pops thru the night.
Only place which may see a few storms through about 01Z would be
the ern zones where some sfc boundaries laid down by previous
storms, and better shear is available. Certainly by late evening
and overnight should be dry through the CWA. A little drier air
moves in behind this system tonight, so Tds may drop off a bit,
but still on the humid side, with lows a degree or two lower
than last night, probably cooler in the mountains.
Previously...Jet streak moving into the Northeast is leading to
a broad area of upper divergence over the forecast area this
afternoon and into the evening. Given the warm and humid air
mass in place at the surface...there is sufficient instability
for thunderstorms. Areas of enhanced surface convergence...like
heating of the terrain or sea breeze boundaries...will be the
most likely focus for convection. There is also a s/wv trof
approaching that may allow convection to persist across the Nrn
zones past the loss of daytime heating...but otherwise diurnal
cooling will signal the weakening of most storms. Until that
time any stronger updraft could produce a strong wind gust or
two given effective shear around 35 to 40 kts.
Some patchy fog is possible late tonight...especially any areas
that picked up a little rainfall today. With the boundary fairly
stagnant over the area...low temps will be similar to the past
couple of nights.
.SHORT TERM /6 AM FRIDAY MORNING THROUGH FRIDAY NIGHT/...
Fri expect similar temps overall...as mid level temps remain
fairly consistent. Wly flow may allow for a little extra
downslope warming in the favored locations. Another weak wave
is forecast to approach the area during the day...and will
likely spark another round of widely scattered showers or
storms. We also take another step down in humidity...and Fri
night should be a little cooler than the previous days.
.LONG TERM /SATURDAY THROUGH THURSDAY/...
The models remain in decent agreement on the long wave pattern
through the first half of next week. Thereafter, we continue to
see big differences emerge regarding the degree of residual
troffiness here in New England downstream of the central CONUS
ridge. Overall, we're likely to see both heights and temperatures
run below average for much of the extended period. We begin the
period with a westerly flow and a broad low amplitude trough here
in New England. The weak ridging promised for Sunday in response
to digging upstream shortwave energy over the Great Lakes has all
but disappeared. The upshot is that the baroclinic zone will stall
further north over New England...and any clearing will be confined
to the international border area as well as our eastern Maine zones
as high pressure over eastern Canada briefly noses into the forecast
area. By the start of the new work week, this shortwave energy has
carved out a sizable trough across the Great Lakes and northeast
CONUS. The trough axis will inch eastward across the region through
the first half of next week keeping the region seasonably cool
and unsettled. In the dailies...we begin the period with a cold
front stretching from our international border area through northern
Maine into New Brunswick. This cold front will settle south across
the region Saturday and Saturday night with clouds and scattered
convection. By Sunday morning...the boundary will be stalled
across southern New England with any clearing confined to the
international border area and our northern and eastern Maine zones
as high pressure briefly noses in. Elsewhere...it'll be a mostly
cloudy day with the best chance for showers across southern and
western New Hampshire. By Sunday night...the frontal zone will
ride back north with attendant cloud shield as well as increasing
pops and cool unsettled weather in response to evolving upper
trough. This cool unsettled weather is expected to linger through
the first half of the upcoming work week.
.AVIATION /02Z FRIDAY THROUGH TUESDAY/...
Short Term...Widely scattered TSRA will continue into the
evening...weakening after sunset. Confidence is too low to
include at any of the terminals with significant lead time.
Otherwise VFR conditions return tonight. LEB and HIE will be
clear...cool...and calm enough to see some fog possible after
midnight. VFR conditions continue Fri...though an afternoon wave
may spark some SHRA or TSRA in the mtns. HIE could see
precip...but again confidence is low.
Sat...Sct MVFR in -shra/-tsra.
Sun - Tue...areas of MVFR in -shra/-tsra with lcl IFR in coastal
stratus and fog.
Short Term...Winds and seas are expected to remain below SCA
Winds and seas are expected to remain below small craft threshold
through the period.
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