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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCAR 121351
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
951 AM EDT Fri Apr 12 2024

.SYNOPSIS...
A warm front will lift into the Maritimes this morning. Strong
low pressure will track to the west today followed by a cold
front on Saturday. The low will dissipate to our north on
Sunday. High pressure builds in early next week.

&&

.NEAR TERM /THROUGH TONIGHT/...
-- Changed Discussion --
940 am update...Bumped up winds, but no changes to advisory.
Otherwise, watching heavy rain currently west of the forecast
area that will progress eastward during the morning. Did bumped
up precip amounts for today. The primary concern is heavy precip
training into the high terrain in Piscataquis County combining
with snowmelt. At this point, we do not expect the Piscataquis
River to reach minor flooding levels, but will be watching
carefully throughout the day. The intense rainfall rates may
generate small stream and urban flood issues.

Previous Discussion...
A large storm system is lifting into Ontario to the Quebec
border today north of the Great Lakes states. Aloft at 500mb a
deepening upper level low will slide overhead as the system
begins to become vertically stacked into Quebec. At the surface
warm & moist air is advecting northward into Maine this morning
as the surface warm front lifts north into the Canadian
Maritimes. Low-level moisture is allowing for showers across the
area this morning and if no showers expecting drizzle and fog
reducing visibilities at times less than 1 mile with obs showing
1/2 mile at times. This morning the northern branch of the Jet
Stream is combining with the southern branch over the
southeastern United States and turns due north up the Eastern
Seaboard. This will allow the trof to tilt negatively to our
west as the left exit region sets up over the Northeastern
States which will increase surface lift with a new slug of
moisture moving north ahead of a cold front. This will generate
a large area of steady rainfall this morning to our southwest
and that lifts north on the southerly flow. At the same time the
925mb low-level jet rapidly increases and pushes into the
Downeast Coast with winds 70-75kt at 925mb. Modeled PWATs along
the Downeast coast inland perhaps reaching near daily record
levels. Modeled soundings showing a significantly moist profile
(98-100%) suggest with the increase surface lift along the
front that efficient rainfall production is likely. This means
moderate to heavy rain at times is likely across the Downeast
coast inland to the Central Highlands. The best chance of the
heaviest rain combined with snowmelt to result in flooding will
be the Piscataquis River basin (including all the smaller
tributaries). Rainfall totals generally 1-1.5 inches across the
area but isolated areas up to 2 inches possible. In Southern &
Central Piscataquis County it is here a Flood Watch remains in
effect. More details in the Hydrology section below...

Along with the heavy rain that 70-75kt 925mb low-level jet will
punch inland across the Downeast coast into the Central
Highlands and northward despite it weakening further north.
Modeled soundings continue to show mixing of portions of this
low-level jet to the surface. South winds may gust up to
50-55mph across the Downeast Coast to Bangor region and interior
Downeast. Given the extremely soaked soils (>95th percentile
groundwater conditions) and these gusty winds expecting some
isolated power outages possible with tree damage. Across the
rest of the FA expecting gusts 30-45mph with less mixing but
still potentially possible to do very minor tree damage
resulting in a few isolated incidents of power outages. In
addition, with southerly winds expecting a push of water along
the Downeast coast combined with high waves. Not expecting too
much of an issue but more details below in the Tides/Coastal
Flooding section.

High temperatures today will be mild despite the clouds and rain
as 925mb temps warm into the +8C to +11C range from north to
south. At 925mb there is some cold air damming signatures noted
along and northwest of the Longfellow Mtns on the downwind side
of the mountains given the southerly flow. Expecting highs in
the low to mid 50s in the North Woods where that signature is
present. The rest of the area expecting mid to upper 50s today
with upper 40s at the shore given the cold Gulf of Maine water.
Tonight, as the front passes expect steady rain to taper to
isolated to scattered rain showers and some fog is possible.
Southerly winds remain gusty but only 20-25mph expected. The
500mb trof brings a shortwave piece around it over eastern New
York state into the Champlain Valley of Vermont. This keeps the
winds out of the south and given the clouds expecting a mild
night with temperatures in the mid to upper 40s for most
locations expect low 40s at the shore with the wind off the
water.
-- End Changed Discussion --

&&

.SHORT TERM /SATURDAY THROUGH SUNDAY/...
Saturday is expected to be unsettled as an upper low in southern
Quebec lifts north, but a trough extending south from the low will
rotate through Maine with embedded shortwaves and weak disturbances.
At the surface, a trough will also move into western Maine by early
afternoon and move off into New Brunswick by late Saturday evening.
The day is likely to start with low clouds and patchy drizzle and
fog.  Shower chances will be on the increase as the upper trough
moves into the area and combines with moisture and the approaching
surface trough. The best chance of showers will be during the
afternoon with a better chance across the north than along the
coast, although a few scattered showers will likely make it
south into the Downeast Region. Shower chances will gradually
diminish Saturday evening with the loss of daytime heating, but
with the slow moving surface trough still can`t rule out a
shower in spots, mainly across the north. Temperatures Saturday
will be mild and about 10 degrees (F) above average.

Slightly cooler air will follow Sat night with lows mostly in the
mid to upper 30s, but around 40F along the coast. Sunday looks to be
the drier of the weekend days.  The flow aloft goes from weakly
cyclonic in the morning to more of a west/southwest flow in the
afternoon ahead of a rapidly moving system that is expected to move
out of the Great lakes with a surface low to move near Albany, NY by
00z Monday.  The day will be mainly dry with at most an isolated
shower.  Temperatures will be a bit cooler, but still a few degrees
above average.

&&

.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
The afore mentioned low near Albany is expected to track across the
Gulf of Maine Sun night, and this will likely generate a few
showers, mainly across the southern half of the FA. Did go a bit
higher than the NBM Pops and it is certainly possible that later
shifts might need to entertain the idea of a few hours of higher
PoPs. This system looks rather moisture starved so QPF is not
expected to more more than one to two tenths of an inch. The low
pulls away into the Maritimes Monday with lower 500 millibar
heights and perhaps just enough instability and moisture for a
passing showers. The upper trough moves east Tuesday and
Wednesday with ridging building in for dry weather and above
average temperatures. Did go lower than the NBM on the dew
points Tuesday, but left the NBM dew points on Wednesday when
confidence was not as high on the lower dew points. The next
system moves in from the Great Lakes Wed night and Thursday with
increasing shower chances.

&&

.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: IFR/LIFR conditions this morning with -DZ & FG and
low cigs. Expect generally IFR/LIFR today with RA & BR. S-SE
winds increasing this AM. 15-25kt with gusts up to 35kt north
and up to 45kt south. LLWS likely all terms. Tonight, IFR/LIFR
with -RA becoming SHRA and BR possible. Low cigs remain likely.
Winds becoming S 10-15kt with gusts up to 30kt.

SHORT TERM: Sat: IFR in the morning improving to MVFR and possibly
VFR at the Downeast terminals. Local IFR still possible at the
Aroostook terminals in the afternoon in any more persistent
showers. S wind 10 to 20 knots with a few higher gusts.

Sat night & Sun: VFR Downeast, and MVFR gradually improving to VFR
at the northern terminals. Wind shifting west 5 to 15 knots,
increasing to 10-20 kts Sunday.

Sun night: Predominately VFR, but MVFR possible in any scattered
showers. West wind around 5 knots Sun night and 10 to 15 knots Mon.

Mon & Tue: Mainly VFR. W-NW winds 10-15 knots, gusting to 20
knots.

&&

.MARINE...
NEAR TERM: Gale Warning remains in effect until 9pm this
evening. SE winds increase to Gales this morning. Gusts up to
45kt expected this afternoon. Seas building 11-16ft this
afternoon with a wave period 7-8sec becoming 9-10sec this
evening. Tonight winds shift more southerly and fall to SCA
conditions into early morning. Seas slowly subside 7-11ft
tonight with a wave period of 10-11sec. Rain is expected today
with fog to reduce vsby at times. Rain tapers to showers
tonight. Sea surface temperatures from the Downeast coast out
25nm and east to the Hague Line including Passamaquoddy Bay are
39-41F.

SHORT TERM: A small craft advisory will likely be required this
weekend on the coastal waters for wind gusts of 25 to 30 knots and
seas 8 to 11 ft on Saturday, slowly subsiding to 5 to 7 ft by Sunday
afternoon.  Conditons on the intra-coastal waters will mostly be
below SCA levels, but can`t rule out low end SCA on Saturday. The
wind and seas are expected to be below SCA levels on Monday and
Tuesday with seas mostly 3-5 ft along the coastal waters.

&&

.HYDROLOGY...
Widespread rainfall will fall on snow today into this evening
across the Central Highlands and Northern Maine where snowfall
remains present. Isolated areas of heavy rain is possible to
fall in a short period of time. Latest NOHRSC analysis and Maine
Cooperative Snow Survey Program shows areas of 1-4 inches of
snow water equivalent (SWE) sitting on the ground. Rainfall
totals expected 1-1.5 inches across the area with isolated
higher amounts possible. NOHRSC analysis shows the snowpack
temperatures 31.9-32F which indicates the pack is very ripe with
significant melting expected. Latest modeling suggests 1-2
inches or more of the SWE may melt out combining with the
rainfall to create significant runoff. The ground remains
partially frozen with above normal groundwater conditions which
suggests absorption is unlikely...resulting in nearly complete
runoff. The best chance of significant runoff will be across the
Piscataquis River basin impacting all the smaller rivers and
streams along with the Piscataquis itself. The latest river
model ensembles (GEFS, HEFS & NAEFS) for the Piscataquis River
at Dover-Foxcroft (DOVM1) gives a 10-30% chance of reaching
minor flood stage tonight into Saturday. The latest forecast
from the Northeast River Forecast Center (NERFC) has DOVM1
reaching Action Stage on this evening but remaining around a
half foot below flood stage. We will likely see significant
rises on the smaller rivers and streams like the Sebec &
Pleasant Rivers along with the Kingsbury Stream. Given this
concern, the Flood Watch remains in effect for portions of
Southern & Central Piscataquis County to cover the entire
Piscataquis River basin. This lines up with the Weather
Prediction Center (WPC) Day 1 Excessive Rainfall Outlook of a
"Slight Risk". This slight risk does go into the southern
Penobscot River basin mainly impacting urban and smaller
tributaries along the Penobscot.

Along the Downeast coast there is no snowmelt and although
grounds are very soaked and heavier rain will be present, not
expecting any flood concerns at this time. WPC Day 1 Excessive
Rainfall Outlook has the remainder of the CWA in a "Marginal
Risk" which seems fine with the combination of rain+snowmelt
across the north and short duration heavy rainfall in the
Downeast region.

&&

.TIDES/COASTAL FLOODING...
For the afternoon high tide near 230PM today, we do expect
storm surge of 1 to 1.5 foot, but the astro tides are not
expected to be high enough to cause any major issues or coastal
flooding. Wave runup may cause minor issues and a Coastal Flood
Statement is possible, especially given that the seas will be
running 12 to 16 ft on the coastal waters by this afternoon.
With wave action, water may just reach the Deer Isle Causeway,
but inundation is not expected.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Flood Watch through this evening for MEZ010-031.
     Wind Advisory until 8 PM EDT this evening for MEZ015>017-029-
     030.
MARINE...Gale Warning until 9 PM EDT this evening for ANZ050>052.

&&

$$


Near Term...MCW/Sinko
Short Term...CB
Long Term...CB
Aviation...MCW/Sinko/CB
Marine...MCW/Sinko/CB
Hydrology...
Tides/Coastal Flooding...