Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 291302

Area Forecast Discussion
National Weather Service Caribou ME
902 AM EDT Fri May 29 2020

A very warm and humid air mass will remain in place across
northern and eastern Maine today. An approaching frontal system
will bring increasing chances for showers and thunderstorms
this evening into tonight. A few stronger thunderstorms may
produce locally heavy rainfall and gusty winds. Cold front will
move off the coast Saturday afternoon. Much cooler Sunday but
unsettled. High pressure will build into the region Sunday night
and remain into Tuesday.


900 AM Update: We xtnded the mention of patchy marine fog ovr
Downeast coastal Maine til nearly midday, with immediate coastal
areas possibly experiencing some fog all day. Otherwise, we
raised hi temps across the far N a couple of more deg based on
trends seen from latest sfc obs, fcst aftn 925mb temps, and air
mass continuity from ystdy.

Orgnl Disc: Another very warm and humid day on tap for the
region especially north of the Downeast region. Daytime temps
will be able to reach well into the 80s, especially n of the
coastal region. This area will see a SSW flow which will keep
things cooler along w/some clouds. Dewpoints n of the coast will
climb back into the mid/upper 60s by later this morning. Not
expecting any records to be broken today as has been the last
few days. Increasing clouds by the afternoon across the n and w
will cap temp a bit lower.

SPC has kept portions of northern Maine, including the Maine Central
Highlands and all of western Maine in a Marginal Risk for the
potential for severe thunderstorms late this afternoon into tonight.
A pre-frontal trof moving out ahead of the strong cold front will be
the focus for convection to fire. A strongly sheared environment
w/CAPE values of 1000-1500 joules should be enough to get storms
going. Sounding data, especially the NAM showed 0-6km shear of 35-40
kts w steepening llvl lapse rates(0-3km). Mid level lapse rates
appear to be marginal, but w/40 kt jetstreak at 850-700mbs is
progged by the NAM and HRRR to move into the region, should be
enough to aid in organized tstms. The NAM sounding profiles
indicate the potential for strong wind gusts. PWs to increase
more later today into tonight as upper flow taps the Gulf of
Mexico as seem on the 00Z UA. Activity becomes more organized
w/storm mode being cluster of storms and line segments. Added
the gusty winds along w/the heavy rainfall. Decided to back up
the timing of the activity until later this afternoon for the
western areas and gradually bring the action ene tonight.

The activity will become more organized as it moves ene as the
cold front pushes toward the western Maine border. Given the SW
flow aloft, the front will be slow to move across the area
overnight. Heavy rainfall is a given looking at the warm cloud
layer through 11K ft and SSW through 700mbs. Training cells
could lead to torrential rainfall potential w/the risk of some
flash flooding especially back across the w and nw areas.
Further se, the atmosphere will be stable to offset any
advancement of the strong convection. Although, as the activity
pushes further e, some elevated convection is possible as noted
by the sounding data. Added isolated tstms for these areas


A weak area of low pressure will track north of the state on
Saturday with a cold front crossing the region from west to east.
Expect the chance for showers and a slight chance for thunderstorms
Saturday morning, as a 500 MB short wave, moves northeast across the
region. The front will dissipate as it reaches the coast later
Saturday afternoon. Saturday will be a much cooler day with highs
generally ranging from the low to mid 70s. A secondary front will
cross the region Saturday night with a chance  for showers, mainly
across the north. A much cooler and drier air mass can be
expected on Sunday, with afternoon highs only expected to range
from the upper 50s to lower 60s North and mid to upper 60s
central and Downeast.


An upper trof will remain across the region Sunday night through
Monday with below normal temperatures. There will be the
potential for some patchy frost Sunday night across the North if
winds decouple. The upper trof axis is expected to cross the
region Monday afternoon. The cold air aloft combined with
diurnal heating may result in few showers during Monday
afternoon. The upper trof axis will move east of the region
Monday night with fair weather expected. By mid week, a 500 MB
low center will be across northern Quebec province with a west
to northwest flow aloft across the forecast area. Disturbances
sliding through the flow aloft could result in mainly afternoon
showers through mid week.


NEAR TERM: Today...VFR for the northern terminals w/the chance
of seeing some MVFR cigs briefly this morning, especially from
KHUL to KPQI. KBGR and KBHB will deal w/MVFR and IFR this
morning in low cigs and patchy fog. KBHB will have LIFR this
morning. Some improvement to VFR for KBGR later this morning.
KBHB will improve to MVFR later this morning and then VFR. SSW
winds 10-15 mph w/gusts 20-25 mph. LLWS for KBGR and KBHB

Tonight...Showers and tstms, mainly for the northern terminals
w/conditions down to MVFR/IFR. Some storms could contain strong
wind gusts and very heavy rainfall. Across the KBGR and KBHB
airfields, a return back to MVFR and IFR w/potential for LIFR.
Showers and isolated tstms late at night. SSW winds continue at
10-15 mph.

SHORT TERM: Sat...MVFR in sct showers and slight chance tstm
early, then improving to VFR afternoon. S to SW wind 10 to 15 kt
early, becmg W to NW afternoon.

Sat Night thru Tuesday...Mainly VFR.


NEAR TERM: 900 AM areas of marine fog for
tdy and tngt.

Prev Disc...SCA has been extended through 5AM Saturday. SSW
winds are picking up over the waters w/the outer zones seeing
gusts in the lower 20s attm. Strong llvl jet of 40-45 kt as
noted by the NAM will push across the waters later this
afternoon into tonight. This will bring sustained speeds up to
20 kt w/gusts of 25+ kt. The intra- coastal zone will see less
wind w/the stable layer in place. Seas will continue to
gradually build to 5-6 ft by later tonight. Showers and possibly
an embedded tstm possible.

SHORT TERM: Wind/seas could be near SCA levels Saturday into
Saturday evening, otherwise wind/seas will remain below SCA
levels through the period.


MARINE...Small Craft Advisory until 5 AM EDT Saturday for ANZ050-051.



Near Term...VJN
Short Term...Duda
Long Term...Duda
Marine...VJN/Duda is the U.S. government's official web portal to all federal, state and local government web resources and services.