Scientific Forecaster Discussion
Area forecast discussion...updated
National Weather Service Gray ME
647 am EDT Tuesday Sep 16 2014
a weak cold front will push offshore today. A secondary cold front
will approach from the north tonight and Wednesday and will slide
south of the region Wednesday night. High pressure will build in
from the west Thursday through Friday. High pressure will shift
offshore Friday night and will hold off the coast through
Near term /until 6 PM this evening/...
only minor changes to the forecast for this update to reflect the
showers on radar and convective trends. Other weather elements
are on track this morning.
light showers already in progress mainly over southern New Hampshire in
poorly organized warm air advection regime. WRF-nmm model has the
best handle on convection this morning so have used this model the
first few hours. Forcing is not impressive with this system nor is
moisture so am expecting more of what we are seeing at present
through the afternoon before the better forcing moves east. The
pre frontal trough stretches from near kpsm northward to the St
Lawrence Valley...and will shift south and east during the day.
This will help focus rain on the mesoscale ahead of the actual
cold front which moves through this afternoon and provides another
source of lift. Still probably will see only a couple tenths of an
inch by this afternoon. Highs will range in the upper 50s north to
Short term /6 PM this evening through 6 PM Wednesday/...
drier air helps usher in cooler air overnight behind the front.
Light winds and clearing skies will help support good radiational
cooling conditions. This will lead to overnight lows in the upper
30s with a few middle 30s filtering into the mountains and foothills.
Lower to middle 40s should be as low as the locations in the coastal
plain drop. Wednesday looks a bit warmer than Wednesday...
especially for the coastal plain...as the cooler airmass moderates
quickly. Clouds develop over the north as a backdoor front drops
towards the Canadian border...but the rest of Maine and New Hampshire will
enjoy mostly sunny skies.
Long term /Wednesday night through Monday/...
cold front will gradually push south through the region Wednesday
night. Will likely continue low chance probability of precipitation mainly for northern
zones Wednesday night. Very little forcing with this boundary so
not looking for much in the way of shower activity. Variable
cloudiness overnight will help to keep temperatures up and expect lows
ranging through the 40s.
Morning clouds will quickly give way to mostly sunny skies Thursday
with highs ranging through the 50s north and lower to middle 60s
south. Northwest winds will be gusty at times.
Light winds and clear skies will allow for some of the coldest temperatures
of the season Thursday night. Expect a hard freeze in the north
where lows will dip into the middle to upper 20s. Central and
southern interior sections of Maine and New Hampshire will see a
widespread frost with lows ranging through the 30s. Coastal
sections will bottom out near 40 but some low spots could see some
Sunny but cool weather continues on Friday as high pressure crests
overhead. High temperatures will top out around 10 degrees below normal
with most areas not making it out of the 50s.
High pressure will slide offshore Friday night with return flow
bringing somewhat warmer air back into the region for the weekend.
Highs Saturday will edge back into the lower to middle 60s for most
Cold front will approach from the west on Sunday but may squeak
out one more nice day with highs reaching the lower 70s in warmer
Aviation /12z Tuesday through Saturday/...
short term...some brief LIFR/IFR conditions possible this morning
over the mountain terminals primarily due to fog...otherwise
expect prevailing MVFR to VFR ceilings for this light rain event
ending between 18z- 21z today. Winds will be light and eventually
Long term...VFR Wednesday night through Saturday.
short term...small craft advisories may be needed Wednesday
afternoon through Thursday morning as waves increase above 5 feet.
Long term...sca's may be needed Thursday night and early Friday.