Scientific Forecaster Discussion
fxus61 kgyx 200719
Area forecast discussion
National Weather Service Gray ME
319 am EDT Thu Jul 20 2017
a weak cold front stall over the area today...allowing for
another warm day to its south. Temperatures are forecast to
climb into the upper 80s to near 90 again across much of
southern New Hampshire and nearby western Maine. Another round
of showers and thunderstorms are possible this evening and
overnight...but the best chances look to be across southern New
England and New York state. Temperatures look to warm a few
degrees more into the end of the week and early as westerly flow
takes over. A low pressure system may bring cooler weather and
more potential for rainfall Sunday night into early next week.
Near term /today/...
warm and humid conditions expected again today with a sea breeze
becoming established along the Maine coastline. Based on
sounding analysis, expect maximum heating potential today to be
about the same as yesterday, generally right around 90 in areas
that are able to realize this potential. With a broader
westerly flow today, the sea breeze will be shaped a little
differently today, more oriented along the coast and inland of
the midcoast. However, with such a steep low level inversion,
early morning warming could warm things up into the mid 80s
before the sea breeze becomes established enough to cool things
With the heat and humidity, there will be instability available
for thunderstorms during the afternoon. However, there is not
much of a trigger available until a shortwave trough moves in
late in the evening. So until then, expect the best chance of
convection to be driven by the terrain and perhaps the
convergent zone along the sea breeze boundary. Some mesoscale
models are showing some development over the Adirondacks
drifting east into New Hampshire during the afternoon as well as
some development along the sea breeze. But generally speaking
this should be fairly isolated if it does occur. Wind shear
today will be broadly supportive of more organized
thunderstorms, though the shear is unidirectional and very deep.
As such, it seems the greatest threat for severe weather will be
for damaging winds, and that threat will be fairly small.
Short term /tonight and Friday/...
afternoon convection which develops over western New York will
begin to push its way east and southeast overnight. It is
possible that some of this activity scrapes southern New
Hampshire, but the odds are better further to the south.
Generally expect mostly cloudy skies from the passing mid level
wave and debris from other convection and lows falling into the
Flow becomes a little more northwesterly on Friday, and as such
we expect dewpoints to be a bit lower, generally around 60
during the heat of the day. This northwest flow will also squash
the sea breeze down to the immediate coastline with temperatures
warming into the upper 80s to near 90 in well mixed areas. A
front drops in from the north late in the day and could provide
a focus for showers and thunderstorms arriving in the late
afternoon across northwest Maine.
Long term /Friday night through Wednesday/...
warm and relatively quiet weather is expected Friday night
through at least the first part of Sunday with offshore flow and
little in the way of forcing for ascent. Thereafter, the pattern
begins to change as more amplified upper level troughing takes
shape. Starting Sunday night, a warm front looks to lift toward
the region with the attendant likelihood for rain as agreed upon
by several members of the 00z deterministic/ensemble model
suite. Preliminary indications are that this trough may stick
around for awhile, perhaps providing for an unsettled, showery,
and cool pattern into early next week.
Aviation /06z Thursday through Monday/...
short term...expect VFR conditions today with light winds. There
will be a chance of valley fog tonight, but the chances are much
lower than previous nights due to expected cloud cover and lower
Long term...mainly VFR Friday night through Sunday. For Sunday
night into early next week it looks like chances for IFR
conditions increase in showers, low clouds, and perhaps some
short term...light southerly flow expected today and Friday.
Long term...conditions are expected to remain below small craft
levels through the weekend. There is a chance of Small Craft Advisory conditions
early next week in association with a possible low pressure