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-- Discussion containing changed information from previous version are highlighted. --
000
FXUS61 KCAR 260112
AFDCAR

Area Forecast Discussion
National Weather Service Caribou ME
912 PM EDT Wed May 25 2022

.SYNOPSIS...
-- Changed Discussion --
High pressure continues to slide further offshore overnight,
followed by a warm front lifting to the north on Thursday. A
cold front then slowly approaches from the west through Friday
night, then crosses the area Saturday and Saturday evening. Weak
high pressure then builds in through Sunday night, followed by
a warm front lifting north on Monday.
-- End Changed Discussion --

&&

.NEAR TERM /THROUGH THURSDAY/...
-- Changed Discussion --
9:12 PM Update: High pressure in the Gulf of Maine will slowly
retreat to the east through Thursday with an increasing return
flow across the region. Satellite pictures show high clouds
streaming toward the region from the west. A mainly clear sky is
expected late this evening with increasing high clouds
overnight. Temperatures are now in the upper 40s/low 50s along
the coast with mid 50s to low 60s for most inland locations. The
00z Caribou sounding was fairly dry like last night. Very minor
tweaks were made to the hourly temps and dew points based on
the latest observations and expected conditions, but overall
changes were minor.

Previous discussion:
High pressure centered over the Gulf of Maine will remain in
the area tonight. 850-300mb RH models show clear skies early
tonight, but the approaching warm front will push high level
clouds in before midnight, then mid and low level clouds after
midnight. Early clear skies will help with radiational cooling,
but the late cloud cover should even temps out to upper 40s
across the region. QPF models and SREF are pointing to the
development of the marine layer tonight over the waters due to
high pressure sitting over the waters. With SW flow, it is
possible for some fog/low stratus to make it onshore. Decided to
add patchy fog to the coastal Downeast regions.

By Thursday, the approaching warm front will start to lift N
across Quebec in the morning. Increasing cloud cover will help
keep temps slightly below normal throughout the day. 925Mb
indicates warm air overrunning cold air, which will help
increase moisture in the afternoon with the S flow. Rain is
expected to begin once the warm front settle to the north of the
state. Upper air model soundings indicate fairly dry air in the
low and mid levels for the south, thus decided to keep the rain
north of the Bangor Region. As the front moves north, the high
pressure over the waters will slowly make its way E. This
will tighten the pressure gradients as the low level jet moves
S. Winds will increase across the region, but especially along
the coast where gusts could reach up to 25 mph.
-- End Changed Discussion --

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...
This time frame will feature a battle between deep layered
ridging centered off the mid-Atlantic Coast and northern stream
shortwaves going over the top of the ridge over SE Canada. The
trend in the models is showing less flattening of the ridge by
these shortwaves, this will help keep the surface frontal
boundary up in Canada for longer than previously expected.

While the surface warm front is to the north to start Thursday
evening, the 850 hPa warm front is still catching up and should
lift through northern portions of the CWA through the night. As
a result have chance pops and higher mainly to the N of the
Bangor Region with areas from on around Bangor on South likely
staying dry. Pops should diminish from S to N through the night,
with any precipitation likely confined to the Crown of Maine by
Friday morning (if not totally into New Brunswick). Lows
Thursday night should run 5-10 degrees above normal. Patchy to
areas of fog is probable over at least coastal Downeast Maine
with a strong marine layer with onshore flow.

Friday morning should be mainly dry, except for possibly around
the Crown of Maine. A passing northern stream shortwave Friday
afternoon should bring some showers to the region, and possibly
a rumble of thunder, with the best chance for any precipitation
across the North. Downeast Maine, especially nearer the coast
could end up dry through the day. However, with strong onshore
flow, the marine layer will be rather strong, so low clouds and
patchy fog could still be in play there, even with no
precipitation. Highs on Friday could be quite mild, especially
in the Central Highlands/Upper Penobscot Valley (depending on
exact strength/orientation of the Marine layer and the exact
areas impacted by the passing shortwave). Highs should run 5-10
degrees above normal, except possibly up to 15 degrees above
normal in the Central Highlands/Upper Penobscot Valley.

Another passing northern stream shortwave, coupled with the
upper trough and surface trough creeping ever closer from the
west should bring more widespread precipitation over the area
Friday night than during the day on Friday, though confidence
is lowest in this over Downeast Maine, especially coastal
areas. There is the potential for an area of locally heavy
rainfall Friday night with any stronger convection. At this
time, the best chance for this appears to be areas mainly from
Mt Katahdin on North. Given the relatively dry antecedent
conditions no hydrologic concerns are anticipated. Lows Friday
night should be around 15 degrees above normal.

The axis of a northern stream trough pushes into the area by
Saturday afternoon, ahead of this axis (and its associated
surface cold front) locally heavy rainfall is possible with any
stronger convection. With 500-1000 J/kg of CAPE, surface
dewpoints into the upper 50s-low 60s, the region in the right
entrance region of a 100+KT 300 hPa jet, and 40-50KT of 0-6km
Bulk Shear there is some potential for strong to possibly severe
storms as well. With the flow in the low-mid levels becoming
more parallel to the Maine Coast, the marine layer might not be
much of an influence in keeping stronger convection at bay. At
this time the confidence in any strong to severe storms is not
high enough to reflect this threat in the HWO.

For now highs on Saturday are forecast to be near normal.
However depending on the strength of the warm push ahead of the
cold front and its actual timing, they could be a bit higher
especially for areas S/E of Mt Katahdin.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...
While the CMC continues to show a cutoff low impacting the
region Sunday and Monday, the GFS/ECMWF and their ensembles do
not show much support for this, so followed a ECMWF/GFS blend
in the long term.

The northern stream trough axis exits to the east Saturday
evening, bringing an end to any lingering showers with it over
Downeast Maine. This is followed by WNW flow aloft through
Sunday. With dry low levels it should be dry late Saturday night
and Sunday.

The region is then under WNW-NW flow aloft Sunday night -
Wednesday with the region in between a deep layered ridge
centered over the Ohio River Valley and a cutoff low over the
Canadian Maritimes. While it should be mainly dry during this
time frame, shortwaves coming down the front side of the
ridge/backside of the cutoff low could bring bursts of showers
and possibly a rumble of thunder as well. Historically this
pattern is also favorable for severe weather if Mesoscale
Convective Complex can develop over Quebec and then maintain
itself as it advects ESE-SE into the area. While there are some
signs this could occur in the models, there is far to much
uncertainty to pick any one solution as being right or wrong. It
is best at this time just to recognize the generic threat, and
realize that for most, if not all locations this threat most
likely will not materialize.

Temperatures should be near normal Saturday night, then above
normal Sunday- Wednesday.

&&

.AVIATION /01Z THURSDAY THROUGH MONDAY/...
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NEAR TERM: Mainly VFR for all terminals with possible MVFR/IFR
in patchy fog for Downeast terminals late tonight with light
and variable winds. Confidence on fog was not high enough to
include in the 00z Tafs. On Thursday, VFR for all terminals in
the morning, then MVFR/IFR in the afternoon for the Aroostook
terminals due to rain. S winds 5-10 kts in the morning, then
10-15 kts in the afternoon with gusts up to 25 kts.

SHORT TERM:
Thursday Night: MVFR or lower possible. S-SE Winds G15-25KT,
LLWS possible. S-SSW Winds G15-20KT possible Thursday evening at
northern terminals. LLWS possible southern terminals.

Friday-Saturday: MVFR or lower possible. Thunderstorms possible
Saturday. S-SW winds G15-20KT possible at northern terminals and
LLWS possible at southern terminals into Saturday ahead of the
surface cold front. NW winds G15KT possible behind the cold
front.

Saturday night-Monday: Becoming VFR Saturday evening.
-- End Changed Discussion --

&&

.MARINE...
-- Changed Discussion --
NEAR TERM: Winds and seas below SCA conditions tonight. Low
visibilities possible in patchy fog. By Thursday, winds and seas
will be below SCA in the morning, then winds increase quickly in
the afternoon to 25 kts. Thus a Small Craft Advisory has been
issued starting Thursday afternoon.

SHORT TERM: SCA has been issued for all waters for Thursday
night. This likely will need to ultimately be extended on all
waters through at least Saturday. SCA conditions could linger
on the coastal ocean waters east of Schoodic Point Saturday
evening, other wise sub-SCA conditions are expected Saturday
night-Monday.
-- End Changed Discussion --

&&

.CAR WATCHES/WARNINGS/ADVISORIES...
ME...None.
MARINE...Small Craft Advisory from 2 PM Thursday to 6 AM EDT Friday for
     ANZ050>052.

&&

$$

Near Term...CB/LaFlash
Short Term...Maloit
Long Term...Maloit
Aviation...CB/LaFlash/Maloit
Marine...CB/LaFlash/Maloit