Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
707 PM EDT Monday Oct 20 2014
low pressure over the eastern Great Lakes will move to the
southeast tonight and Tuesday and will intensify south of Long
Island Tuesday night....bringing an extended period of rain to
the area. Low pressure will meander off the southern New England
coast Wednesday through Friday before drifting off to the
northeast on Saturday. A cold front will cross the area Sunday
followed by a ridge of high pressure for Monday.
Near term /until 6 am Tuesday morning/...
7pm update: tweaked evening sky grids to reflect more cloud cover.
Input latest observation data and temperatures/dewpoints look on track. No other
changes at this time.
weak 500mb ridging between closed low exiting the Maritimes to
the NE...and deepen trough over the ph valley will allow for a mainly
dry night...although this will allow for more stagnant surface flow
overnight...as the middle levels become more srly toward daybreak. Look
for the onshore to develop stratocu...especially over the coastal
plain and in the southeast upslope areas. High and middle clouds will move
in from the west in advance of the system to our west..which
begins to close off by morning. There will be a slight chance of a
very light shower toward daybreak. Temperatures will drop off quickly
this evening...as clear skies hold until a round midnight...but
once the clouds move in...temperatures will remain steady through the latter
part of the night....with lows middle to upper 30s north and 40 to 45
Short term /6 am Tuesday morning through Tuesday night/...
surface flow remains generally weak...and will likely see a bit of a
cold air damming situation with NE winds inland...and a more east
flow near the coast...with a coastal front developing. This
combined with middle level warm air advection...will produce a steady rain by
afternoon on the coastal plain and into the foothills. In the mountains
and points north...will be more showery into the afternoon as the
downslope helps dry things a bit...but even here the warm air advection will
produce steady rain by late in the day. Highs will work their way
into the upper 40s north to meteorological impact statement 50s on the coast...as the the marine
air works in.
Tuesday will see a mainly steady light rain continue overnight as
warm/moist air advection continues. The winds will gradually pick
overnight as the surface low begin to form S of Long Island New York...but
the heaviest rain and breeziest conditions will hold off until
Wednesday. Mins will drop back into the 40s Tuesday night.
Long term /Wednesday through Monday/...
the models are in general agreement on the long wave pattern
well into next week. We begin the period with a closed low near
the Delaware-Maryland-Virginia. The upper low will slowly meander northeast along
the coastline through Friday night before exiting into the
Maritimes on Saturday. At the surface...low pressure will be
situated just offshore and drift slowly northeast through the middle
Atlantic and New England coastal waters Wednesday through Friday
before exiting the region by Saturday. We'll see bands of rain
pinwheeling in off the Atlantic Wednesday through Friday...with
the heaviest rain likely falling Wednesday and Thursday. Quantitative precipitation forecast
amounts on the order of 2 to 4 inches are likely across the
forecast area with localized 5 inch totals possible across the
western Maine mountains. On Saturday...some lingering clouds and
widely scattered showers mainly across the higher
terrain...despite weak ridging behind the upper low. More
unsettled weather for Saturday night and Sunday as a quick moving
shortwave drives another cold front across the area. A ridge of
high pressure follows for Monday.
Aviation /23z Monday through Saturday/...
short term...VFR should hold through much of tonight...with gradually
deteriorating conds beginning toward daybreak as onshore flow
moves stratus and rain inland on Wednesday...by Wednesday afternoon should see
coastal areas down to IFR...with inland areas following by Tuesday
Wednesday - Friday...IFR in rain and fog. NE surface wind gusting to 25 knots.
Sat...scattered MVFR possible in showers.
short term...winds/seas continue to diminish overnight and into
Tuesday morning. Will see east flow begin to pick up Tuesday
afternoon and especially Tuesday night...with Small Craft Advisory seas/winds expected
by midnight...and building to gales by Wednesday morning.
Wednesday - Thursday...gale force winds are likely.
Friday...small craft conditions are likely.
main Stem rivers will need to be monitored closely middle to late week.
Most small rivers and streams will likely have sharp rises as
well. The heaviest rainfall is expected to be over south-central
Maine and the northeast facing higher terrain. Again...mostly 2-3 inches
quantitative precipitation forecast with localized amounts approaching 5 inches.
coastal flooding is a possibility as the system makes a loop over
Long Island New York on Thursday. Wave run up tools indicating
some beach erosion and splash over across much of our
coastline. Near shore waves could top out in the 10 to 15 foot
Marine...gale watch from late Tuesday night through Thursday morning