Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
1020 PM EDT Wednesday Oct 1 2014
upper level low pressure slowly shifts offshore through Thursday.
At the surface...high pressure builds in from the northeast
through Thursday and remains over the area through Friday. A cold
front will approach from the west on Saturday and crosses the
region Saturday night. A weak ridge of high pressure will build
in behind the front on Sunday. A weak warm front will pass to the
northwest of the region on Monday followed by a cold front on
Near term /through Thursday/...
latest radar animations continue to show most of the precipitation
confined to the southern New England coastline. However...one new
batch of precipitation with a few scattered showers are making it about
as far north as Portland. Mesoscale models continue to show this last
spoke of energy cross the region from east to west through about
Have adjusted the probability of precipitation...dew point values and current temperatures based
on lastest conditions. Have also introduced patchy fog...along
with the drizzle for far southern areas per current observations.
The rest of the forecast package will remain unchanged.
low pressure continues to spin near Cape Cod this
afternoon... directing moisture onshore and keeping showers and
drizzle going over New Hampshire and much of western Maine. Most of the rain
shield remains over Cape Cod to Long Island and the Gulf of
Maine...but steady rain is falling over the New Hampshire coast to Cape
Elizabeth and inland. This trend will continue through the evening
and into the early morning hours before the inverted trough
feature shifts clockwise and southward towards Boston. Only light
precipitation amounts are expected.
Drizzle and fog will plague portions of the coast and the coastal
plain for several miles...as well as mountain valleys and the CT
River Valley overnight. Stratus will be slow to lift but will
begin to break down late morning Thursday. These features will
keep overnight lows on the warm side.
Short term /Thursday night through 6 PM Thursday/...
at the same time the surface trough shifts south...the upper
level low begins to shift east and high pressure begins to nudge
into New England from the north. As a result rain chances quickly
taper off to none after the early morning hours Thursday. As
mentioned before...stratus will begin to lift around noon and
skies clear from north to south. Temperatures warm into the middle to
upper 60s areawide by Thursday afternoon.
Some cooler air does funnel in from the north by Thursday night
into Friday morning but winds will be non zero interrupting
radiational cooling. In addition...other factors such as +11
degrees c at 850mb and clouds indicated by a jetstreak aloft will
keep it from getting too chilly. Although we will see temperatures
in the 40s with some upper 30s in the mountains...not expecting it
to be nearly as cold as one model suite indicated.
Long term /Thursday night through Wednesday/...
surface high pressure will be centered over the Canadian
Maritimes with a ridge extending southwest along the northern New
England coast on Friday. A brief upper ridge crosses the area as
well... exposing the region to some warmer temperatures. It
appears only the northwestern part of the area will really be able
to feel this as the southern and coastal areas will be under the
influence of onshore surface flow... keeping temperatures cooler.
Highs will range from the upper 60s in the northwest to near 60 at
the coast. Some fog and drizzle may move in from the ocean Friday
night... though models often bring this in too often and too early.
Large upper trough will move through the Great Lakes on Saturday
with a surface cold front surging eastward across the northeast.
An area of rain is expected to form within the rising motion of
the upper trough and along and ahead of the surface front... with
the rain arriving in western New Hampshire by later in the day on
Saturday. The rain and surface front move across New Hampshire and
Maine Saturday night. Expect the entire area to see rain with this
system so went with very high pop. A little lower pop was used in
western New Hampshire where there is still some timing uncertainty
over whether the rain will fall late Saturday or early Saturday
night but overall confidence in rain across the region is very
With colder air moving in aloft with the upper trough and
warm/moist air surging northward in the low levels ahead of the
surface front... there will also be a chance for a few
thunderstorms embedded with the rain. Lapse rates near moist
adiabatic combined with strong lift could be enough for a few
Cooler and drier air moves in behind the front for Sunday... but
more sun and a downsloping west wind could actually warm coastal
areas up to the low 60s... a few degrees warmer than Saturday
before the front.
From Sunday through the middle of next week the northeast will be
in a southwest flow around the large upper trough over central
Canada. This will mean gradually warming temperatures with
occasional bouts of rain showers as minor waves pass through the
Aviation /02z Thursday through Monday/...
short term...varying ceilings and visibilities at times through
noon tomorrow in showers...drizzle...and fog...for all stations.
LIFR to IFR conditions are likely in the 03 to 13z time frame.
Long term...VFR Friday but could see marine clouds and fog move in
Friday night and Saturday with IFR or lower conditions becoming
widespread especially east of the mountains. Rain and possibly
some embedded thunder moves through Saturday night with VFR
conditions returning for Sunday and Monday.
short term...extended the Small Craft Advisory through Thursday
evening. May be able to change it just to a small craft for waves
tomorrow morning as winds will likely come down tomorrow morning
as surface trough moves away.
Long term...winds will gradually turn from the northeast to east
and then southeast through Saturday as offshore low pressure moves
away and surface high pressure over the Maritimes and Maine
gradually shifts east as well. Flow may strengthen into advisory
criteria again on Saturday night ahead of a cold front.
Wave heights may stay near or above 5 feet and require a Small
Craft Advisory for all or part of the area all the way through
Marine...Small Craft Advisory until 8 PM EDT Thursday for anz150-152-