552
FXUS61 KCAR 100141
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
941 PM EDT Tue Jul 9 2024

.SYNOPSIS...
A weak surface trough crosses the area tonight. Remnants of
Beryl tracks into Quebec by late week with a front stalling over
Maine. A cold front clears the area by Saturday morning as
another disturbance approaches from the northwest Saturday
afternoon.

&&

.NEAR TERM /THROUGH WEDNESDAY/...
935 pm update... There is a decent amount of instability
remaining into the night and will be watching for isolated
thunderstorms tonight. Otherwise, attention is focused on the
remnants of Beryl for later tomorrow and the associated Flood
Watch in Piscataquis County. Initial 10/00Z guidance continues
to favor a corridor stretching into southern Piscataquis County
with rainfall amounts of 2 to 3 inches by Thursday morning.

Previous discussion...
A weak trough will continue cross the forecast area tonight.
This boundary will act as a source of lift for showers and
storms, especially across the northern half of the CWA. For
Downeast, showers and storms are more driven by diurnal heating
and around 1500 J/kg of CAPE. The threat for storms will quickly
diminish tonight however, as temperatures begin to drop into the
evening hours. That said, a few rain showers may linger through
the area until around midnight tonight. Fog will likely move in
from the waters tonight into the coastal Downeast region, and
could locally be dense with visibility less than a mile. Further
inland, patchy fog will develop, and dense fog will be most
likely anywhere which sees rain this afternoon and evening.

For the day on Wednesday, another warm and humid day is on tap,
but less warm than previously due to the recent weak trough that
came through and the increased cloud cover as the remnants of
Beryl head towards our area. Highs will lift into the lower 80s
across the north and mid 80s Downeast. Showers and storms will
begin to move into the area from the SW through the late
afternoon hours. With PWs forecast to be above 2.0 inches and
near all time record for the Downeast area, tall skinny CAPE
profiles on CAMs forecast soundings, saturated forecast
soundings, warm cloud layer forecast to surpass 10 kft in depth,
efficient warm rain processes increase the threat for heavy
rainfall in any showers that enter the area late in the day on
Wednesday. Should these storms be numerous to widespread by
Wednesday evening, the risk for flooding will greatly increase.

&&

.SHORT TERM /WEDNESDAY NIGHT THROUGH FRIDAY/...
Excessive Rainfall with Beryl Remnants Expected Wednesday Night
into Thursday AM with additional heavy rainfall from scattered
storms Thursday.

Setup...Maine will be in the right entrance region of a
powerful jet streak to our north that will enhance upper level
divergence across the region which increases surface
convergence. At the same time a 500mb trof will be diving into
the Great Lakes with the surface remnants of Beryl working into
Western New York heading for the Quebec/Ontario border then
Quebec. Ahead and to the east a warm front will be lifting and
stalling over Maine to be the focus for precipitation. A strong
tropical moisture connection will be established up the US
Eastern Seaboard transporting significant moisture into the
area. The area of strong PVA will set up allowing for strong
ascent along the front to force precipitation. Expecting
widespread precip to develop across the area with the focus
being the front.

Timing...Showers and t-storms blossom through the evening hours
Wednesday and become widespread by late evening. Heaviest
precip ends by Thursday AM with showers continuing Thursday.

Rainfall...PWATs are expected to climb into the 2-2.3 inch
range across the Downeast into the Central Highlands including
the Moosehead Region to Southern Baxter region. PWATs to the
north expected to be on the order of 1.4-1.9 inch range. This is
significantly above climatology with areas exceeding the 95th
percentile with Central Highlands to Downeast coast reaching all
time record high PWATs. GYX RAOB record for 00z July 11th is
2.16 inches with an all time record of 2.34 inches (7/16/2023
12z) which is the same environment over Downeast areas. If you
factor in models sometimes struggle with best modeling PWATs it
still places our southern zones in near record level PWATs. CAR
PWATs expected to reach 1.6-1.65 inches by 00z July 11th which
is 0.2 inch above the 90th percentile, although not record
breaking it will be well above normal for July 11th (00z July
11th record 1.85in). Expect the strong vertical ascent along and
just north of the front which will result in the heaviest rain
mainly across the Central Highlands from 00z-12z Thu.
Additionally, modeled soundings show the warm cloud layer to
extend 13-14.5kft which is well favorable for efficient
rainfall production. It is during this roughly 12hr period we
expect widespread 1-2 inches of rain with isolated higher
amounts possible. There is some concern this could fall in a
rapid period of time (less than 12hrs) that could pose an
excessive runoff threat. See the hydrology section below for
more details...

Thunderstorms...Elevated instabilty along the front with a few
hundred joules of CAPE may allow for isolated thunderstorm
activity embedded in the heavier rainfall. Cannot rule out
lightning especially in the Central Highlands near the front.
Any thunderstorms will enhance rainfall more than already
expected.

Fog...Temperatures and dew points in the 60s will result in
patchy to areas of fog to develop in the evening with the
increased moisture and light winds. Downeast areas may
experience some dense fog especially from the shoreline inland
to Route 9 with the Marine fog bank pushing in. Rain+Dense fog
may cause significantly reduced visibility for any overnight
travel.

Uncertainty...The location of the front is still a concern
where it exactly positions itself as there remains uncertainty
in the latest 12z models (and ensembles). This will be the focus
of of the heaviest rainfall. Tropical environments in Maine
cause a ton of different and sometimes under modeled situations
given the statistical anomaly this event is expected to
be...This add a level of uncertainty that some locations have
the potential to exceed the current rainfall that is expected.
Additionally, with the dry soils there is some uncertainty on
how much runoff can be expected versus actual absorption of the
rainfall.

Thursday...temperatures warm into the mid 70s with dew points in
the upper 60s north and low 70s south will result in a warm +
humid day. The low of Beryl remnants will be drifting north in
Quebec and with the boundary still hanging around as a cold
front and triple point push closer to the Champlain Valley of
Vermont then NH/Quebec border. This means with warm moist air
and some breaks of sunshine expecting more showers and
thunderstorms to develop in the afternoon. MUCAPEs reaching
500-1000j/kg will provide some instability, lapse rates aren`t
the best with the warm pocket around 825mb. PWATs will remain
above the 90th percentile in the 1.6-1.9 inch range and with
still 25-35kt of shear present cannot rule out some robust
storms to produce heavy rainfall.

&&

.LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/...
Beyond for Friday into Next Week looks to be warm and humid
thanks to the Beryl remnants really changing the pattern. A
strong Bermuda surface high sets up with overall long wave trof
so that favors an unsettled weather pattern. Overall SW flow
throughout the atmosphere favors warm and humid conditions with
temperatures in the 80s during the day, high humidity and 60s in
the morning. Days that we do get shortwaves expecting chances of
showers and thunderstorms. This summer pattern looks to stick
around through potentially mid next week.

&&

.AVIATION /02Z WEDNESDAY THROUGH SUNDAY/...
NEAR TERM: VFR conditions will continue into this evening across
all terminals, with brief MVFR possible at BGR in TSRA early
this evening. For tonight, fog will move onshore from the
waters, likely bringing BHB down to IFR/LIFR late tonight. BGR
could also see IFR conditions should the fog move in further.
Additionally, patchy fog may develop across other terminals,
especially any terminals which see rain this afternoon.
Confidence in any one terminal seeing fog is low at this point,
so left BCFG at KHUL up through KCAR. Winds W to SW around 5
kts, with higher gusts possible in any showers and storms.

VFR conditions will return across all terminals Wednesday
morning, but cigs will gradually lower through the day ahead of
moderate to heavy rain which will move in Wednesday evening. A
few thunderstorms are possible around the KGNR/KBGR area
Wednesday afternoon. Winds W to SW around 5 kts, with higher
gusts possible in any showers and storms.

SHORT TERM: Thursday...VFR/MVFR with brief IFR due to SHRA & TS.
AM FG may cause IFR/LIFR at BGR & BHB. Heavy rain is possible
with any SHRA/TS activity. E-SE winds 5-15kt.

Friday...VFR. Brief cat lowering with SHRA. SW winds 5-15kt.

Saturday...VFR. Brief cat lowering with SHRA/VCTS mainly
northern terms. W-SW winds 5-15kt.

Sunday...VFR. Brief cat lowering with SHRA/VCTS at PQI, CAR, FVE
in the afternoon.

&&

.MARINE...
NEAR TERM: Winds/seas are expected to remain below SCA levels
tonight through Wednesday. Areas of fog will reduce visibility
to less than 1 NM at times tonight.


SHORT TERM: Winds/seas below SCA condition through Thursday
night. Rain/fog may reduce vsby Wed night into Thu AM. Patchy
fog likely continues into Thu with a chance of tstms over the
intra- coastal waters possible on Thu. Fog and showers possible
into Friday. Brief SCA conditions with waves 5-6ft possible over
the outer waters on Friday. Winds up to 25kt possible over the
outer most waters. Into the weekend generally a few showers but
below SCA conditions with just some fog causing issues in the
AM.

&&

.HYDROLOGY...
Potentially excessive rainfall to cause scattered flash
flooding possible Wednesday night into Thursday morning. Any
flash flooding will be mainly localized impacting mainly
vulnerable area including urban areas, hilly terrain roads,
small rivers, streams and creeks and washout prone locations
including dirt/gravel roads and ATV trails. WPC has issued a
Slight Risk Excessive Rainfall Outlook for a large portion of
the CWA for Wednesday Night into Thursday AM (D2) and continues
into D3. Showers and thunderstorms through this evening will
soak the grounds as rainfall rates will not cause flooding but
soaking the grounds ahead of tomorrow nights rainfall will be a
concern. Soil moisture continues to run below normal across much
of the Downeast and Central Highlands with well above normal
conditions in portions of the North Woods into the Aroostook
River Basin. Main stem rivers are not going to flood with this
event. However, near record level PWATs, strong dynamical
support and well efficient rainfall production (warm cloud
layer 13-14.5kft) will be a concern for excessive rainfall. At
this point the greatest concern will be in Southern Penobscot
County along with Southern and Central Piscataquis County. A
flood watch has been hoisted for this area from Wednesday
Evening through Thursday morning. However, cannot rule out the
need for isolated flash flood warnings in areas outside of the
watch or the need for expansion of the watch. Those planning on
driving overnight, camping, hiking or riding ATV trails through
these areas should stay alert to rapidly changing conditions
Wednesday evening into Thursday AM.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...Flood Watch from Wednesday evening through Thursday morning
     for MEZ010-015-031.
MARINE...None.

&&

$$


Near Term...AStrauser/MCW
Short Term...Sinko
Long Term...Sinko
Aviation...AStrauser/MCW/Sinko
Marine...AStrauser/MCW/Sinko
Hydrology...