Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 200413
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
1213 AM EDT Thu Jun 20 2019

.SYNOPSIS...
High pressure will move away to the east tonight as a frontal
boundary stalls across the north. Low pressure will approach on
Thursday and track across the Gulf of Maine Thursday night.

&&

.NEAR TERM /THROUGH TODAY/...
Update 12:15 AM: Have adjusted wind, temperature, and dew
points based on latest observations. No other changes.

Previous discussion:
High pressure to our east combined with a stalled front across
the north will channel moisture into the area tonight.
Convergence along the front combined with some cape up to 300
J/KG will produce showers and some embedded thunder, mainly over
western and northern areas, this evening. Some showers and areas
of drizzle will continue late tonight into Thursday morning. Low
pressure over the upper Midwest, supported by an upper trough
digging through the Great Lakes, will approach on Thursday. This
will bring a steadier, heavier rain into the Downeast region
Thursday with some lighter rain pushing up across the north.
Convergence along the coastal front may support some isolated
thunder near the Downeast coast Thursday afternoon. Humid air
lifting north across the Gulf of Maine will likely produce areas
of fog over the Gulf of Maine tonight into Thursday.

&&

.SHORT TERM /TONIGHT THROUGH SATURDAY/...
Overall trend for heavy rain to impact the area Thursday night,
namely Downeast, continues as multiple forms of guidance
suggest strengthening low pressure to track near the Gulf of
Maine coast. Exact from of this low will be ironed out, but both
a flat, quick traverse such as the GFS suggests and a intense
low pressure center off the coast as the NAM suggests, would
prove equal chances of elevated rainfall rates. Kept mention of
patchy fog across all areas Thursday night.

PWATs advertised just shy of 2 inches Downeast are well above the
climo 75 percent average of 1.22in at GYX. 850Mb moisture
transport also puts much of this moisture advecting over
portions of coastal Downeast before shifting SW or parallel.
This region is also outlined when analyzing the Precip Potential
placement parameter for heavy rainfall, combining PWAT and mean
low-level RH. Sufficient warm cloud layer depth exceeds 13kft
across portions of interior Downeast, with greater than 10kft
just north of a HUL to GNR line. Thus, only limitation in precip
efficiency will be the lack of a long, skinny CAPE profile.
This is due to the warm airmass creating relatively weak lapse
rates. However, the potential duration of the event from
Thursday night thru late Friday morning will result in training
showers across locations that look to accumulate impressive QPF
amounts. At this time, most of Downeast stands a shot at
localized QPF totals close to 2 inches, with less to the north.
Upper-level dynamics will need to be stronger to go much more
widespread, as some of the deterministic runs could be showing
convective feedback with erroneous high QPF bullseye. In any
case, have introduced moderate and heavy rain from Thurs evening
into early Friday morning for Downeast and central areas.

As low exits, precip will linger as showers Downeast to the
north, making Friday a washout for much of the south. Tapering
begins in the evening with much of Friday night into Saturday
becoming dry across the north and western areas. Strong NW flow
on backside will bring chance for isolated showers Sat evening.
All guidance agrees on nosing in high pressure Saturday evening
into Sunday.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
Dry conditions anticipated Sunday and Monday, with Monday being
the most cloud free. Temperatures look to run in the upper 70s
Downeast. Even the coast will see a quick jump in temps during
the morning as offshore flow looks possible. Clouds increase
during the evening ahead of another system to bring rain to the
region. This will be located along a front from an occluding low
traveling from the Upper Midwest into lower Canadian Provinces.
Duration of the rainfall will need to be refined as there remain
a few outcomes. Canadian has a more progressive track eastward
keeping northern and eastern Maine under precip, while ECMWF and
GFS solutions have it stalling up near James Bay. This also
stalls the frontal system with showers possible. Will need to
watch how large upper ridge decays or remains intact Monday for
how progressive system becomes.

&&

.AVIATION /04Z THURSDAY THROUGH MONDAY/...
NEAR TERM: Still VFR at the terminals, but conditions will
lower to MVFR then IFR late evening and overnight in lowering
clouds and showers over the region. The conditions are expected
to lower first along the coast, and after midnight at the
Aroostook County terminals. LIFR to IFR conditions are expected
Downeast on Thursday with IFR to MVFR conditions are expected
across the north.

SHORT TERM: IFR expected Thursday night with rain and patchy fog.
Rain may be heavy at times at Downeast terminals with further
reduction in vis. Improvements will be felt first across
northern terminals Friday morning trending to MVFR. Isolated
showers are possible across the north Saturday afternoon. high
pressure moves in Sat night with VFR expected across all areas
through Monday.

&&

.MARINE...
NEAR TERM: The wind and seas are expected to remain below SCA
tonight and Thursday. Moist air over the waters will likely
result in fog and reduced visibilities tonight and Thursday.

SHORT TERM: Areas of fog expected to linger Friday morning. Waves
will gradually increase to 3-4 ft through Saturday, but stay
below SCA criteria. Winds will follow suite, 15-20kts. Winds and
waves will subside into Monday.

&&

.CLIMATE...
The high temperature this afternoon in Caribou was 80 degrees.
This is the first 80 degree day of 2019. On average (1981-2010
averages), the first 80 degree day is observed on May 23rd. This
was the latest date for the first 80 degree day since 2000, and
ranked as the 7th latest date for the first 80 degree day on
record (Period of record since 1939) in Caribou.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...None.

&&

$$

Near Term...Mignone



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