Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
319 PM EDT Sat Aug 30 2014
high pressure centered south of the Maritimes will continue to
shift eastward overnight. A cold front will approach from the
northwest on Sunday...before stalling nearby Monday. Another cold
front will approach our region from the west on Tuesday...before
crossing Maine and New Hampshire Tuesday night. High pressure will
build back over New England Wednesday through Friday.
Near term /through tonight/...
high pressure to our east will continue to shift further east
tonight allowing a warm and moistening southwesterly flow to continue. The
moistening airmass may allow for fog and stratus to develop
late...especially along the coast. Otherwise...an approaching cold
front from the west should stay far enough west to keep most
everyone dry tonight although a few showers may make their way
into western New Hampshire late.
Short term /Sunday through Sunday night/...
a short wave trough and attendant surface cold front will move into
the area on Sunday. While lack of steep middle-level lapse rates will
be a cape robber...deep layer shear...very moist low levels...and
approaching forcing for ascent should be sufficient for the
development of thunderstorms during the afternoon. A few could be
strong to severe with wind damage and torrential downpours the
Sref mean precipitable waters rise to around 2 inches so training
cells could produce localized flash flooding. The WRF-nmm and
WRF-arw models and a few others point at southern New Hampshire and
southernmost ME as the Hot Spot for organized storms late Sunday
afternoon and evening...and this seems reasonable given that/S
where the best instability looks to be. However...most areas
should see showers and storms tomorrow.
Otherwise...the last day of August will feel July-like...with
temperatures well into the 80s and dewpoints around 70. The shower
and thunderstorm activity will wane by middle to late evening.
However...with the frontal boundary expected to stall nearby...a
warm and muggy night should remain in the cards Sunday night.
Long term /Monday through Saturday/...
broad warm air advection pattern continues to develop for the
first half of the week as low pressure ejects out of the northern
plains and deepens as it moves through central and eastern
Canada. A warm front lifts over the northeast allowing very warm
moist air to pool over the region. 850mb temperatures as warm as
18 degrees c work into the area ahead of a cold front. This will
work to cap some convection...but we will see some showers and
thunderstorms overcome the cap each day as short waves and
surface boundaries will not be hard to come by.
The most significant of these days will be Tuesday into Wednesday
as the main cold front associated with the Canadian surface low
crosses New England from west to east. This will be a relatively
slow moving system and points towards possible flash flooding.
The latter half of Wednesday as well as the remainder of the work
week look dry. Temperatures look above normal with a few cooler
nights (wednesday and thursday) possible thanks to radiational
cooling and cooler air filtering in behind fronts. A reinforcing
shot of cooler air may arrive by next week as well as more rain.
Aviation /19z Saturday through Thursday/...
short term...some fog and stratus may develop tonight in the
moistening airmass...especially near the coast and in river
valleys. This may lead to a 3 to 6 hour period of IFR conditions
in spots late tonight into early Sunday morning. Otherwise...
showers and thunderstorms are expected during the day on Sunday
with their associated lower conditions and gusty surface winds/heavy
Long term...IFR to MVFR conditions in valley fog possible Monday
morning for a few hours. Deteriorating conditions likely Monday
night through Tuesday from west to east in showers and lowering
clouds. Improvement comes middle morning Wednesday with VFR most of
the day. Some residual low level moisture likely for patchy dense
fog Thursday morning...otherwise VFR Thursday.
winds and seas gradually increase in the return flow around the
high this evening and we should reach marginal small craft
conditions tonight outside the bays...with lingering small craft
conditions expected Sunday.
Long term...southerly flow continues over the waters Monday and
Tuesday with another frontal passage late Tuesday into early
Wednesday. There may be borderline small craft winds ahead of this
front but waves should stay below criteria. Northwest winds follow for a
24hr period or so before turning southerly once again.
Marine...Small Craft Advisory from 7 PM this evening to 7 PM EDT Sunday