Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
243 PM EDT Friday Jul 31 2015
a weak cold front will cross the area Saturday...bringing another
threat for showers and thunderstorms. Behind this front we will
see another drop in temperatures and humidity. Weak low pressure
aloft...situated over Quebec...will bring a threat for showers or
storms Monday and Tuesday. Cooler air and unsettled conditions
move in for the middle to end of next week. By late in the
week...low pressure may form along the middle Atlantic
Seaboard...bringing more rain to our region.
Near term /through tonight/...
at 18z...a weak surface trough was exiting the coast...with a surface
cold front situated over the Great Lakes. GOES water vapor showed
an upper low centered over Hudson Bay. Another warm day across the
area...but noticeably less humid as westerly flow introduced drier
air behind the front. Instability clouds will melt away this
evening with loss of heating. Over night...outside of a few stray
clouds for the mountains...mostly clear with [patchy late night
valley fog. Lows will range from 50s in the mountains to lower
and middle 60s elsewhere.
Short term /Saturday through Saturday night/...
on Saturday...a shortwave impulse pivoting around the upper low
will cross the area along with an associated cold front. High
temperatures will warm into the 70s and 80s. With cooler air
moving in aloft...and lowering freezing levels...some of the
stronger cells may produce hail near severe threshold...along
with strong wind gusts. The best convective coverage will be
far northern New Hampshire into the mountains and foothills of
Maine. For now...i've limited enhanced wording to gusty winds and
small hail and confined the area to far northern and eastern
sections of the forecast area given some continued uncertainties.
Convection should end quickly Saturday evening with loss of
heating and as cold front clears the coast. Some clouds and
widely scattered showers could linger in the higher terrain...otherwise
a mainly clear and seasonably cool night with lows in the lower and
middle 50s in the mountains...and in the 50s to around 60 elsewhere.
Long term /Sunday through Friday/...
a highly persistent pattern will continue across the Continental U.S. Over
the next week or so. A large upper level ridge of high pressure
will remain over the western United States while a persistent
cyclonic flow continues over the northeast.
A more significant upper level low will begin to dig southward
from Canada on Monday. This...in conjunction with a slow moving
cold front will cross New England late in the day and in the
evening hours. Expect isolated severe weather with the potential
for large hail and damaging winds which will continue into Monday
Strong cyclonic flow aloft will allow for more scattered showers
on Tuesday with possibly a thunderstorm. Similar conditions will
occur on Wednesday...with mainly diurnally driven showers due to
steep lapse rates associated with very cold air aloft. The
mornings will likely begin with plenty of sunshine...with clouds
quickly building and thickening over the region with the daytime
On Friday...cyclogenesis will likely occur along the southern New
England coastline with yet more upper level energy digging south
from Canada. This slow moving system in combination with deep
tropical moisture will likely bring periods of heavy rainfall
Aviation /18z Friday through Wednesday/...
short term /through 12z Sat/...scattered MVFR possible by the way 08 - 12z Sat in
valley fog and stratus. Scattered MVFR 16 Sat - 00z sun in rain showers and
thunderstorms and rain. Scattered MVFR possible once again by the way 08 - 12z sun in valley fog and
Long term...mainly VFR Sat night through Tuesday... with valley fog
possible each night. Scattered rain showers/thunderstorms and rain will impact most of the
terminals late Monday and Monday night.
short term /through Saturday night/...southerly flow late Sat and
Sat evening may briefly approach small craft outside the bays
ahead of a cold front...otherwise quiet weather is expected this
Long term...persistent SW flow Sunday and Monday could bring
higher swells to the coastline Sunday night....which could linger