Area Forecast Discussion
Issued by NWS Caribou, ME
FXUS61 KCAR 281917
Area Forecast Discussion
National Weather Service Caribou ME
317 PM EDT SUN AUG 28 2016
A low in Quebec will drag a warm front across the area tonight,
followed by a cold front on Monday. High pressure returns Monday
night into Tuesday. Another frontal system will affect the area
Tuesday night into Wednesday.
.NEAR TERM /THROUGH MONDAY/...
Low pressure currently spinning over west central Quebec will
continue to push eastward overnight, dragging its attendant cold
front in its wake. Showers will develop out ahead of this boundary
as it moves eastward. This precipitation will move into western
areas this evening and then spread over the area through midnight or
so. There will be some elevated instability; model progs are running
850-700MB CAPE of up to 300 J/kg and lapse rates will be 6-6.5 C/km.
This will be enough for a few rumbles of thunder this evening.
Overnight lows will be in the lower to mid 60s in most locations.
For Monday...the front will be stretched across northern Maine in
the morning hours and will move offshore during the day. Scattered
showers will linger over mainly northern areas through much of the
morning, but overall expect a drying trend through the day. Downeast
will likely see sunshine by afternoon as winds turn northwest. Highs
will range from around 70 in the upper Saint John Valley to the
upper 70s interior Downeast.
.SHORT TERM /MONDAY NIGHT THROUGH WEDNESDAY/...
The models are in good agreement through the period. A low
exiting the area into the Canadian Maritimes. Higher pressure
building into the area from the southwest. The high pressure will
dominate the weather through early Tuesday afternoon. A cold front
will push into northwest Maine by the end of the period.
Loaded a blend of the GFS/GEM/NAM/ECMWF to smooth out the minor
differences in the models. Loaded NAWAVE4 for seas in the coastal
waters. Loaded windgust by factor tool. For QPF used RFCQFP for
first 12 hrs and a GFS for the rest.
.LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/...
For Wednesday evening, went above consensus guidance with pops and
added a slight chance of thunderstorms as a vigorous upper level
trough will accompany a cold front across the area in the evening.
Am favoring a slightly slower progression of the cold front in
line with NAM and ECMWF guidance. This front will bring a
significant air mass change for the remainder of the week as
a fall-like Canadian air mass arrives. On Thursday, a deep upper
trough in Quebec will amplify and keep afternoon showers in the
forecast...mostly in the north. Temperatures will drop to the
upper 60s north and lower 70s south. The upper trough will cross
Thursday night. Went above MOS guidance for lows and kept slight
chance pops for showers in the north along with a lot of cloud
cover. This cloud cover persists in the north on Friday as
northwest winds strengthen and bring clouds southward to Bangor
and the Down East region. Will keep slight chance pops in the
north for a few sprinkles. Highs will be just above 60F in the
Saint John Valley and only reach the upper 60s for Bangor. Went
below MOS guidance for highs on Friday. Dew points will be
dropping down into the 40s on Friday. The cool air mass remains in
place through Saturday before a southwest wind warms temperatures
back into the 70s across the entire forecast area on Sunday.
.AVIATION /19Z SUNDAY THROUGH FRIDAY/...
NEAR TERM: VFR conditions will persist through 00z Monday, then
expect deteriorating conditions as showers and scattered
thunderstorms associated with a cold front will cross the region.
Ceilings will lower to below 1000 ft by 06z Monday and remain so
through 12z-14z. Improvement is expected thereafter as clouds will
lift and thin out. Northern terminals will likely remain MVFR
through a good part of Monday afternoon, while the southern sites
will be VFR by 18z.
SHORT TERM: VFR conditions for all sites through Tuesday afternoon.
Cigs will begin falling Tuesday afternoon becoming VMFR in
showers and thunderstorm late Tuesday afternoon. Shower will
continue into late morning Wednesday. Wednesday afternoon VFR
conditions will return to the area as higher pressure builds
across the region.
NEAR TERM: Headlines are not expected through Monday. South winds will
increase and gradually become southwest overnight into early Monday
in response to a cold front approaching from the west; gusts up to
20 kt will be possible. The front will cross the waters Monday
afternoon, allowing winds to turn offshore. Waves are expected to
build overnight as well, mainly in south swell. Much of the guidance
is showing waves reaching 5 ft over the outer waters by Monday
morning, but much of the guidance has been overdoing the wave
heights over the past 12-24 hours or so. So the current thinking is
that seas will peak out around 4 ft Monday morning, and then subside
through the day as winds turn westerly. Therefore, no Small Craft
Advisories will be needed.
SHORT TERM: High pressure will dominate the weather conditions
for the coastal waters through the Tuesday. Seas will build to
around 5 ft towards the end of the period, otherwise winds and
seas will remain below SCA criteria through the period.