NWS Caribou, Maine Area Forecast Discussion

FXUS61 KCAR 270111

Area Forecast Discussion
National Weather Service Caribou ME
911 PM EDT Thu May 26 2022

A cold front 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. A weak cold
front approaches Monday night and Tuesday.


9:12 PM Update: Light rain continues to fall across much of
Aroostook County. Most areas across northern and central
Aroostook County have picked up from one to three tenths of an
inch of rain with as much as 0.45" at Estcourt Station. Amounts
drop off to just a couple hundredths of an inch at Houlton.

It still appears that much of the rain will shift out of the
far north by around midnight, but another incoming shortwave
and area of low pressure will cause scattered showers/drizzle
to re-develop into a steadier rain across the far north toward
morning. Loaded the past few hours of observed data and made
just minor adjustments for the expected conditions the remainder
of the night.

Previous discussion:
Rain currently extends from the North Woods SE into Northern
Washington County ahead of a surface to 850 hPa warm front. As
this warm front lifts to the north/northeast, the rain will go
along with it. The question for tonight is does the 850 hPa warm
front lift north of the northern Maine/Canada boarder enabling
the rain to come to an end across the Crown of Maine. Latest
CAMs suggest that precipitation should linger across far
Northern Maine through the night, though could become more
spotty in nature by late evening. It could then pick up in
coverage again late tonight in response to a passing shortwave.
Lows tonight should range from around 50 to the mid 50s, which
is around 5 to 10 degrees above normal. There could be some
patchy fog overnight across coastal Hancock and coastal and
central Washington Counties depending on exactly how the marine
layer evolves overnight.

With the axis of a deep layered ridge centered off the Mid
Atlantic Coast still to the west through the day on Friday -
subsidence under the ridge likely will keep the southern 1/2 to
2/3rds of the CWA dry Friday. Across the North, the frontal
boundary in the vicinity coupled with passing shortwaves could
bring some scattered to numerous showers, especially in the
afternoon. In addition with showalter indices down around 0,
there is the potential for some elevated convection mainly
across the North as well. With surface based CAPES fairly
meager, the potential for any surface based convection is rather
low on Friday as a result so is the risk of any strong
convection. Based on the surface/850 warm front being progged
just to the north, would expect the risk for locally heavy
rainfall during the day to be just north of the area as well -
however cannot completely rule this out right along the northern
border of Maine/Canada.

Highs on Friday should range from the mid 60s around the Crown
of Maine and the immediate coast, to the mid-upper 70s across
portions of the Central Highlands/Upper Penobscot Valley/Bangor
Region. This is near normal across the northern and southern
extremes of the CWA and around 5-10 degrees above normal across
the center.


Friday night, southwest flow will continue over most of the
region behind a warm front crossing E Canada. This will bring in
abundant moisture and set the stage for heavier rainfall on
Saturday. As the upper level trough approaches, instability
will increase over western Maine. Additionally, a low level jet
will strengthen ahead of the front, adding to some bulk shear.
This will provide a minimal environment for hail, but the
greater concern will be heavy rainfall. 1.5+ inches of
precipitable water combined with storm motion vectors nearly
parallel to storm development indicate the potential for heavier
precip and storm training. Current QPF forecast through
Saturday has 2 to 3" over 48 hours. With recent dry weather, if
the precip is widespread enough, soils should be able to absorb
quite a bit of rainfall. However, the heavier precip in storms
could overwhelm drainage basins, so precip rate in TS will need
to be watched. Have included heavy rain wording in the forecast.

By Saturday evening, the cold front moves through, speeding up
as it crosses the Downeast. Dynamics will weaken as it moves
eastward, so heavy rainfall is not expected for Downeast. Skies
will clear quickly following the front, and pleasant weather
will return for Sunday.


On Monday, a back door cold front will approach from Canada,
bringing the chance for showers again. Timing on this front
varies between the deterministic models, as well as some run-to-
run inconsistencies with each individual model. Current
forecast reflects the chance for an initial band of showers in
the afternoon, followed by a secondary wave later Monday
evening. This second wave is slightly more consistent with the
models, although positioning is still uncertain. On Tuesday, an
upper level ridge will build into the area, which is increasing
confidence in sunny skies through mid week. Forecast confidence
on temperatures still remains low, since the orientation of the
ridge will determine how much warm air aloft will make its way


NEAR TERM: VFR at all of the terminals as of 9 PM. Conditions
are expected to lower to MVFR overnight, with IFR or lower
possible by morning at KFVE and KCAR and by mid morning at KBHB.

S-SSW winds around 10 KT with some occasional gusts to 15-20 KT
late this evening. Winds become light and variable tonight at
northern terminals. LLWS continues into Friday morning.

Friday night to Saturday: IFR. S to NW winds 5-15G20kt. LLWS and
patchy to areas of fog developing. TS on Saturday, mainly over
western areas.

Saturday night: Becoming VFR. NW winds 5-15kt.

Sunday-Monday: VFR. NW winds 5-15G20kt.

Monday night - Tuesday: MVFR becoming IFR Tues morning. NW winds
10 to 15 kt.


NEAR TERM: Small craft advisory conditions are expected on all
waters through Friday. Fog could limit visibilities to 1NM or
less near the coast late tonight and Friday morning.

SHORT TERM: Small craft winds will continue in SW flow ahead of
the cold front passage on Saturday night. Behind the front,
winds will become NW, with strongest winds moving offshore and
rapidly decreasing below SCA criteria. Waves 4 to 6 feet,
diminishing in NW flow Saturday night to Sunday.


MARINE...Small Craft Advisory until 6 AM EDT Saturday for ANZ050>052.



Near Term...CB/Maloit
Short Term...LF
Long Term...LF

NWS CAR Office Area Forecast Discussion