Scientific Forecaster Discussion

Return to Local Conditions & Forecast

Without Abbreviations
With Abbreviations

fxus61 kgyx 221137 
afdgyx

Area forecast discussion
National Weather Service Gray ME
737 am EDT Tue Oct 22 2019

Synopsis...
an upper ridge shifts east today with increasing clouds and
onshore flow ahead of an approaching frontal system. Widespread
rain, heavy at times, will overspread much of the area this
evening and overnight with gusty winds along the coast. The
system will exit into the Maritimes on Wednesday with high
pressure and drier air to follow for Wednesday night and
Thursday. A cold front will cross the area Friday with a few
clouds and scattered showers. High pressure and drier air
follows for the upcoming weekend.

&&

Near term /until 7 PM this evening/...
730 am update...
forecast is on track with only minor tweaks to morning
temperatures as sites come up and down with radiational cooling
interrupted by incoming cloud cover.

Previously...
patchy fog this morning will gradually clear out as a ridge of
high pressure shifts east, away from the area. Meanwhile a
broad shield of cirrus cloud cover continues to stream over the
area, accompanying falling heights aloft as a broad closed low
approaches from the Great Lakes region. As the column gradually
moistens today, clouds will increase in coverage and depth,
ultimately limiting afternoon temperatures to the mid to upper
50s across lowland locations. Precipitation may begin to creep
into the extreme southern zones by sunset today, however better
forcing coinciding with better available moisture holds off
until later this evening.

&&

Short term /7 PM this evening through 6 PM Wednesday/...
this evening, the broad closed trough aloft rotates negatively
into the northeast, in turn developing a strong southerly to
southeasterly jet on the order of 50-60 kts. The jet picks up
the moist remnants of tc Nestor leading to a period of moderate
to heavy rainfall overnight along with gusty winds, particularly
along the mid coast. The target time period for heavy rain and
wind impacts thus centers around the timing, development, and
eastward movement of the low level jet, roughly 03-12z
Wednesday.

In general models have consistently yielded 1-2" of rainfall
across the mountains, eastern NH, and most of the state of Maine
tonight with a sharp cutoff north of the mountains owing to
favorable southeasterly upslope flow. Much of this could fall
over a 6 hr period as the wave of rain moves SW to NE over the
coastal plain, however 3 hr ffg of 2-3" suggests water impacts
ought to be minimal except locally where fallen leaves may
block drains.

Although it remains unlikely that the strongest winds
associated with the surging jet will mix to the surface over
land due to thermal profiles alone, heavy rain could still
bring a couple 40+ kt gusts to the mid coast surface tonight
into tomorrow morning with sustained winds on the cusp of
advisory criteria. Thus, a Wind Advisory has been hoisted along
western Penobscot Bay tonight into tomorrow morning where
eastward/southeastward facing shoreline will be most prone to
strong winds.

Further south, a wave forms along The Crossing cold front over
the mid-Atlantic, moving up the eastern Seaboard as the cold
front crosses west to east on the heels of the aforementioned
wave of heavy rain. This provides a final round of rain during
mid- Wednesday, after which a trough axis aloft crosses with a
sharp pop cut off to follow as forcing is lost and dry air
intrudes from the west. A brief period of favorable upsloping on
the back end could prolong light shower activity Wednesday but
the area will be dry by Sundown.

&&

Long term /Wednesday night through Monday/...
* no significant weather impacts expected through Sunday.

Models are in good agreement for the exit timing of the fast moving
frontal system out of our forecast area by Wednesday night. High
pressure moves in Wednesday night and exits the area by Friday.

On Friday, a cold front moves through giving US clouds and chance
pops across the area into early Saturday. There is not a good
moisture source for this cold front. Depending on timing, of
the bulk of the scattered showers, some inland areas could see
scattered rain and/or snow showers.

Another round of dry weather dominated by high pressure for Saturday
night through Sunday.

There is a big divergence in the models on when a system will go
through mid Atlantic this weekend/early next week. Depending on
which solution pans out will effect if we have any weather on Monday.

&&

Aviation /11z Tuesday through Saturday/...
short term...
patchy fog lifts in the couple hours following sunrise allowing
VFR to prevail for most of today with easterly flow on the order
of 5-10 kts. High cirrus clouds early will increase in coverage
and depth through the day, degrading to MVFR and eventually IFR
ceilings from south to north this evening associated with a wave
of rain. Periods of IFR/LIFR are likely overnight across all
coastal and coastal plain sites in rain with periods of patchy
fog restrictions in breaks. A period of low level wind shear is also possible
overnight associated with a surging low level jet.

Skies gradually clear Wednesday afternoon with a return to VFR
from SW to NE, although low clouds could hang around north of
the mountains.

Long term...VFR conditions through Thursday night. MVFR
possible with passage of cold front on Friday into early
Saturday.

&&

Marine...
short term... scas develop areawide today as onshore flow
increases ahead of an approaching frontal system. Tonight, 10-15
ft waves develop along with gale force winds across mid coast
waters before subsiding by mid day. Scas area wide persist for
the remainder of Wednesday.

Long term...scas to last into Thursday morning because of gusty
winds and seas.

&&

Hydrology...
a fast moving frontal system crosses tonight into tomorrow with
models continuing to send a wave of moderate to heavy rainfall
S to NE across eastern New Hampshire into central Maine. In general models
have consistently yielded 1-2" of rainfall over these areas
with a sharp cutoff north of the mountains owing to favorable
southeasterly upslope flow. Much of this could fall over a 6 hr
period however 3 hr ffg of 2-3" suggests water impacts ought to
be minimal except locally where fallen leaves may block drains.
Expect modest rises on local Brooks and rivers as a result at
any rate, particularly across the headwaters of the
Androscoggin, Saco, and Kennebec basins.

&&

Gyx watches/warnings/advisories...
ME...Wind Advisory from 10 PM this evening to 8 am EDT Wednesday
for mez027-028.
New Hampshire...none.
Marine...Small Craft Advisory until 8 PM EDT Wednesday for anz153-154.
Small Craft Advisory until midnight EDT tonight for anz150>152.
Small Craft Advisory from noon to 8 PM EDT Wednesday for
anz150>152.
Gale Warning from midnight tonight to noon EDT Wednesday for
anz150>152.

&&

$$
Synopsis...Becker
near term...Casey

National Weather Service Glossary of Abbreviations