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Area forecast discussion
National Weather Service Gray ME
652 PM EDT Thu Oct 17 2019

Synopsis...
a coastal storm will gradually weaken and exit into the
Maritimes by early Friday. Gusty winds are expected to linger
behind this system into the day Friday. High pressure follows
this system for the weekend and early next week.

&&

Near term /until 6 am Friday morning/...
645 PM update...stacked low pressure along the coastal plain of
Maine early this evening will continue to fill and move eastward
and out to sea tonight. Rain chances will continue to
diminish/end across most of the region this evening, with the
White Mountains likely hanging on to upslope rain and snow
showers much of the night. Otherwise, winds continue to be
relatively light at this time, except for gusts around 25 kt
southernmost zones. Winds tonight will likely fluctuate between
light and gusty at times area-wide as the low levels attempt to
decouple.

Previously...

At 18z a 975 millibar low was vicinity of /kizg/ Fryeburg with
an occluded front extending eastward through central and
downeast Maine. National Weather Service Doppler radar mosaic showed bands of showers
pivoting around this feature. While damaging winds ended earlier
today...we'll continue to see gusty winds tonight as the low
center begins to weaken and meanders northeast overnight. Precipitation
will continue to diminish with lingering showers confined largely
to the higher terrain in upslope flow areas. Colder air being
drawn into the back of the system will change rain showers over
to snow showers across the higher terrain where some light
accumulations are likely. Lows tonight will range from the upper
30s to mid 40s.

&&

Short term /6 am Friday morning through Friday night/...
we'll continue to see clouds across northern and eastern
sections on Friday with the storm system meandering near the
Gaspe Peninsula for much of the day. Upslope rain showers will
linger across the higher terrain with snow showers and any
accumulation limited to elevations above 3500 ft. Highs will
range from the mid and upper 40s across the mountains to lower
and mid 50s elsewhere. Northwest winds will gust up to 25 mph.
Clearing Friday night as high pressure begins to gradually build
in from the west. There'll be some lingering upslope clouds and
a stray sprinkle or flurry across the higher terrain for the
first half of the night. Lows will be in the 30s with some 40
degree readings along the immediate coast.

&&

Long term /Saturday through Thursday/...
high impact weather potential:

* no significant weather impacts expected through Tuesday.
* Next significant precipitation chances possible in the Tuesday -
Wednesday timeframe.

--Pattern and implications--

Amplified trough-ridge-trough pattern across North America early
this afternoon with a strong jet west of this across the central
Pacific. This strong upstream jet and lack of significant downstream
blocking /weakly negative nao/ will allow the pattern to remain
generally progressive through the long term forecast period.
Therefore...although we will begin the period under a trough in the
northeastern United States...heights will be building with East
Coast ridging dominating the majority of the long term forecast
period with deterministic/ensemble guidance in agreement on longwave
trough setting up shop over the central portion of the continent.
Overall...this spells temperatures at or above seasonal norms. As
for precipitation...southerly flow on the eastern flank of
developing central noam trough suggests at or above precipitation
potential with a number of potential precipitation producers through
the period.

--Daily details--

Saturday - sunday: cyclonic flow around departing low pressure
system finally loses it/S grip on northern New England as shortwave
ridging and associated surface high building in on Saturday...
cresting overhead Saturday night and then pulling east of the region
on Sunday. This will ensure a period of quiet and dry weather.
Airmass is seasonably cool/dry from a temperature and moisture
standpoint which suggests a good starting point for the forecast.
Lows will range from the upper 20s through mid 30s with highs in the
50s north to lower 60s south /a bit warmer on Sunday with the high
to our east/.

Sunday night-monday: weak shortwave trough passes north of the
region Sunday night with surface high pressure largely remaining in
control through Monday. Low pressure takes shape off the Carolina
coast...but too far south to have any impact through the day.
Expect a somewhat warmer night Sunday night given cloud cover
associated with the shortwave trough with daytime highs mild /upper
50s-lower 60s/.

Tuesday - wednesday: with high amplitude trough to our west...this
period will feature a large low pressure system moving north from
the Great Lakes into central Canada with a slow moving frontal
boundary marching towards the East Coast...with potential
cyclogenesis along this feature as additional energy rotates around
the base of the trough. While deterministic/ensemble guidance is in
good agreement with this overall evolution...there are differences
with an offshore low pressure system that moves well south of the
region Sunday into Monday...and whether any of it/S moisture can be
pulled north ahead of this arriving front. The period certainly
looks warmer than normal /primarily due to overnight lows given
clouds-showers/ under southwesterly flow east of the trough
axis. Otherwise...will continue increasing precipitation chances
with some potential for a relatively significant precipitation
event given ample available moisture and a slow moving frontal
boundary. Ec-eps and gefs have modest 1" quantitative precipitation forecast probabilities for
the Tuesday night- Wednesday period with higher amounts in
individual runs. Certainly Worth watching as our next
potentially impactful weather event.

High pressure looks to return to the region to end the forecast
period Thursday with dry conditions and seasonable temperatures.

&&

Aviation /00z Friday through Tuesday/...
short term /through Friday/...areas of MVFR through tonight in
cigs and sct -shra. VFR Friday with lingering MVFR in mtn
sections in cigs and sct -shra/-shsn. Becoming VFR throughout
Fri evening. Sfc wind gusting up to 25 kt through Friday before
diminishing.

Long term...
VFR Saturday through Monday outside of morning valley fog potential.
Approaching cold front will likely bring a round of restrictions as
early as Tuesday and more likely Tuesday night - Wednesday.

&&

Marine...
short term /through Friday/...winds on the backside will gust to
gales through early evening with Small Craft Advisory conditions likely overnight
and Friday.

Long term...
headline free conditions likely Saturday-Monday. Southerly flow
will increase ahead of an approaching cold front and potential low
pressure system with flags likely in the Tuesday-Wednesday
timeframe.

&&

Gyx watches/warnings/advisories...
ME...none.
New Hampshire...none.

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