Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
701 PM EDT Sat Jul 4 2015
low pressure to our south shifts eastward this evening...bringing
an end to the showers. Weak low pressure will cross just north of
the area late tonight and Sunday morning accompanied by scattered
showers. High pressure brings dry weather and gradually warming
conditions through midweek. Another passing trough will bring the
next chance of rain midweek.
Near term /until 6 am Sunday morning/...
7 PM update: quick update to reflect dry slot allowing clear
skies to develop across much of New Hampshire and now moving into western
Maine. These mostly clear conditions should spread east and persist
the rest of the night over all areas where some gentle downsloping
occurs. No other changes. Perfect night has set up for outdoor
fireworks and festivities.
545 PM update: quick update to take out any mention of the low
chance of showers over extreme southern and coastal areas early
this evening as they have moved off the coast. For the rest of
the night conditions will remain dry except maybe a shower later
in the evening in the mountains. No other changes at this time.
current batch of -shra over southern and central New Hampshire is the result of
700mb deformation zone on associated upper level trough to our northwest
and surface low to the S. Models do indicate that this forcing peaks
around 18z and weakens through this evening as the southern stream system
pulls away from the northern system. Also...the models agree that we
have pretty much seen the farthest eastward and northward progression of the
precipitation...although I would not rule out a few sprinkles working
into interior York/ Cumberland counties through about 5 PM.
Otherwise... the rain over southern New Hampshire will diminish through about
21-22z...leading to a mainly dry evening here...and across the
rest of the County Warning Area.
Evening temperatures should generally be in the middle-upper 60s. The middle-
high clouds are likely to linger through the evening...but should clear out
overnight.. mins will range from around 50 in the north...to around 60
along the coast and in urban southern New Hampshire. The second upper level trough
will begin to swing just north of the County Warning Area toward daybreak...and could
start seeing a few rain showers popping up in the mountains late.
Short term /6 am Sunday morning through Sunday night/...
the weak 500 mb trough passes north of the County Warning Area around midday...so
there is a chance for some rain showers in the northern half of the County Warning Area into
early afternoon...and perhaps a few thunderstorms and rain may be possible as
well...given some lowering 500mb heights...and increasing low level
humidity. Otherwise it looks to be mostly-partly sunny day in the
southern half of the County Warning Area. Highs will top in the middle 70s north...and on the
coast...to the low 80s in southern New Hampshire and interior SW ME.
Sun night looks to be mainly clear...but dew points will be creeping up
into the upper 50s to low 60s by evening...and this will keep mins
generally in this range as well.
Long term /Monday through Saturday/...
Monday will be a hot day with 850 mb temperatures warming to near
14-16 c over portions of New Hampshire and Maine. This will translate to
lower 90s in a few spots. A sea breeze will keep temperatures
right along the coast slightly cooler. Otherwise middle 80s are
expected over the coastal plain with lower 80s in the mountains.
High pressure crests over New England and moves offshore. A short
wave digs into the northern plains helping a surface low deepen
and eject towards the Great Lakes. As the warm front lifts north
isentropic ascent increases and warm showers will kick off across
New Hampshire Tuesday morning... reaching Maine by the afternoon.
A cold front crosses the area Wednesday and in the heat of the
day showers and thunderstorms are likely to develop along the
boundary. Most of the upper level support will be well north but
there will be enough surface based instability and frontogenesis
for some strong storms.
Showers move out Wednesday night. Dry high pressure moves in from
the west and north through Friday. Tuesday and Wednesday will be
slightly cooler due to increased clouds and showers before we see
another increase in temperatures late in the week underneath the
high pressure dome.
Aviation /00z Sunday through Thursday/...
short term...mainly VFR through Sunday...although some IFR or lower
possible in valley fog at khie/kleb tonight and Sun night.
Long term...VFR conditions expected through Tuesday. Showers and
thunderstorms possible on Wednesday as a cold front moves through
creating MVFR or lower conditions in moderate to heavy rain
showers. Improvement to MVFR or VFR is likely Wednesday night
short term...winds will remain on the light side tonight through
Sun night...except for some enhanced S-SW flow along the shore in
sea breeze circulation Sun afternoon. Despite the light winds will
still see some long period swell of 3-4 feet.
Long term...high pressure crosses the waters and winds shift to
light and variable Monday and then southerly on Tuesday. A cold
front moves into the Gulf of Maine Wednesday. Winds with all of
these features should remain below advisory levels as do seas.