Scientific Forecaster Discussion
Area forecast discussion
National Weather Service Gray ME
321 PM EDT Tuesday Oct 21 2014
surface low pressure over New Jersey will move over the Atlantic
and intensify south of Long Island tonight. This system will be a
long duration coastal storm that will bring periods of heavy rain
to the area into Friday. The system will finally drift off into
the Maritimes Friday night. A cold front will cross the area
Sunday bringing another round of showers to the area followed by a
large ridge of high pressure for the beginning of next week.
Near term /tonight/...
large upper low over the Great Lakes has begun to cut itself off
from the main flow while pulling in a long stream of moisture
straight out of the Gulf of Mexico and up the western Atlantic. An
onshore flow above the surface is already causing rain across much
of the region this afternoon. An initial shortwave trough within
the flow has moved north toward Cape Cod and will move through
western Maine this evening. This feature will likely spread
periods of rain into western Maine and New Hampshire. A few
embedded pockets of heavy rain are possible with amounts as high
as an inch possible. With clouds and moisture around...
temperatures will not fall much tonight.
Short term /Wednesday through Thursday night/...
upper low will spin toward the middle Atlantic coast on Wednesday
while a weak mesolow drifts northwest into the Gulf of Maine. A
persistent southeast flow around the upper low will bring a
continual stream of moisture into the region. Aided by lift from
the mesolow and within the upper trough... expect widespread rain
on Wednesday... becoming heavy at times by Wednesday evening.
Primary surface low will form off the middle Atlantic coast on
Wednesday and move toward Cape Cod by Thursday. The moist conveyor
belt of moisture will continue to be pulled back into Maine and
New Hampshire providing rain... heavy at times... through Thursday
evening. As the surface/upper low move into the Gulf of Maine
Thursday night... the moist conveyor belt and heavier
precipitation will likely move to the north and east. But some
light rain is likely to continue especially near the coast as the
low passes by.
Temperatures from Wednesday through Thursday night will not vary
much. Highs and lows may be within 5 degrees of each other...
generally remaining in the 40s and 50s.
Total rainfall amounts of 2 to 4 inches are expected with amounts
in excess of 5 inches possible. While rainfall rates are not
expected to be extreme enough for flash flooding... the prolonged
period of rain and total amounts may be enough to cause flooding
along streams and rivers. A Flood Watch has been issued for the
areas most likely to see river flooding... from eastern New
Hampshire through all of western Maine.
Long term /Wednesday night through Tuesday/...
low pressure in the Gulf of Maine will finally start to pull out
to the northeast...but showers will linger into Friday night.
Following this will will be a shortwave trough that races southeast
across Canada and will drive a cold front through New England on
Sunday. The upper low crossing the area will lead to scattered
showers...especially across the higher terrain and northern
locations. The Euro is still the coldest of the operational models
and some areas across the north could see a few snow showers...but
for now a blend of model guidance keeps any snow showers across
the higher terrain.
Looking like a nice pattern change for the beginning of next week
as a strong high pressure will take control. Ridging over the area
should help push our temperatures well above normal by Tuesday
with t850 of 15c over the region.
Aviation /19z Tuesday through Sunday/...
short term...persistent IFR conditions expected in rain with
periods of LIFR conditions possible through Thursday. To the north
and west of the mountains conditions will not be as bad due to
Long term...IFR to MVFR conditions will likely linger through the
day on Friday and then periods of MVFR conditions into the weekend
with scattered showers possible Saturday and Sunday.
short term...as low pressure tracks across Cape Cod and through
the Gulf of Maine... northeast winds will increase to gale
strength Wednesday and Thursday. The persistent northeast flow
will also allow wave heights to increase especially in the western
Gulf of Maine where 15 feet waves are possible.
Long term...Small Craft Advisory conditions will linger into Friday evening but
mostly due to high seas.
total rainfall amounts of 2 to 4 inches are expected with some
locations possibly exceeding 5 inches. While this rain will not
fall quickly enough to cause flash flooding... the cumulative
effect of this much rain over the next several days may be enough
to bring some streams and rivers into flood. A Flood Watch has
been issued for Wednesday and Thursday when the heaviest rain is
likely to occur. Any flooding which does occur may linger beyond
Thursday as waters slowly drain toward the sea.
tides are only expected to rise to around 9.5 feet or so during
the height of the storm. It would take a surge of 2 feet or more
to cause coastal flooding. At this point... coastal flooding is
not expected. However... the persistent northeast flow may cause a
surge of more than 1 foot and will combine with 10 to 15 feet waves
to create the potential for splash over and beach erosion. The
most likely areas to be impacted will be the seacoast of New
Hampshire and York County Maine.
ME...Flood Watch from Wednesday morning through Thursday evening
New Hampshire...Flood Watch from Wednesday morning through Thursday evening
Marine...Gale Warning from 2 am Wednesday to 8 am EDT Thursday for