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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 260149

Area Forecast Discussion
National Weather Service Caribou ME
949 PM EDT Sun Aug 25 2019

High pressure will remain across the region into Wednesday. A 
cold front will cross the region Thursday with high pressure
building in Friday.


620 PM Update: Only chg this update is fcst hrly temps/dwpts
into the late ngt hrs based on trends seen from recent mid eve 
sfc obs. Based on these trends from the prev fcst for mid eve
which showed very rapid temp falls ovr Nrn vly lctns, fcst 
ovrngt lows (posted at 6 am Mon) were lowered by a deg or two
F mainly ovr these ptns of the Rgn. It appears likely that late
ngt patchy rvr and lk fog will reform ovr the area late tngt 
into erly Mon morn.

Orgnl Disc: Strong high pressure overhead this afternoon with 
light winds, dry air, seasonal temperatures, and barely a cloud 
thanks to strong subsidence. Good radiational cooling expected 
again tonight with high pressure persisting. Not quite as cool 
in the north due to a slight moderation in the airmass, but as 
cool or perhaps a touch cooler Downeast because the center of 
the high pressure is building south a bit tonight toward 
Downeast. Expect patchy fog again tonight, mainly in river 
valleys and near lakes.

For Monday, surface high pressure persists, just migrating a bit
SW to SW Maine. Again, look for low humidity and highs in the 
low to mid 70s. However, looking for more clouds Monday than
Sunday due to a strong low pressure system passing east of us 
from south to north through the Canadian Maritimes. A lot of 
uncertainty still with the track of the low. Worst case 
(furthest west) scenario would bring up to a quarter inch of 
rain in Eastport. Operational GFS is close to this solution. 
However, GFS is an outlier and vast majority of models keep rain
easily east of the Maine/New Brunswick border. Introduced just 
a slight chance of rain for Eastport with no PoPs elsewhere. Do 
believe the low in the Canadian Maritimes will at least send a 
shield of high clouds west into at least the eastern half of the
forecast area, and adjusted sky forecast up a bit to account 
for this.


No significant weather is expected during this period with
surface ridging in control. Monday night will be another cool 
night although it will trend up a few degrees due to the 
increased cloud cover from the Canadian Maritime low. Cloud 
cover will decrease during the overnight hours from west to east
as the low pulls off to the east. Another nice day on Tuesday 
as a 500mb shortwave ridge axis crests over the region with 
mostly clear skies and temperatures running a good 5 to 8 
degrees above normal. Warming trend continues Tuesday night into
Wednesday with lows mostly in the 50s as heights continue to 
rise. Southerly return flow is expected by Wednesday as a weak 
pre-frontal trough approaches from Quebec province. The forecast
challenge during this period over the last few periods was in 
regards to the potential tropical moisture off the Atlantic 
being advected into the region ahead of the pre- frontal trough.
Confidence is still low with some solutions still having the 
potential, but the ECMWF and operational GFS have trended 
further east with the moisture plume. This means confidence has 
decreased overall.


Period will be dominated by broad cyclonic flow with near normal
temperatures and below average precipitation. Wednesday night
through Thursday the pre-front trough and surface cold front
will push through the state. This will bring a period of showers
with QPF amounts expected to remain below .25" at this time but
this could trend higher depending on the coastal tropical
moisture fetch. Quiet weather on Friday with the potential for
an additional cold front Friday night into Saturday with more
light rain showers. Potential still exists for another shortwave
trough later in the weekend and showers. Every trough and
surface cold front will trend temperatures down a few degrees
with a general cooling pattern from Thursday through Sunday.


NEAR TERM: VFR into the evening with very light winds. Patchy 
valley fog late tonight could lead to MVFR or perhaps IFR at TAF
sites typically more susceptible to fog...for example KPQI, 
KHUL, and KBGR. KPQI and KHUL had the fog Sunday morning, but 
not right near KBGR. However, KBGR will have lighter winds 
tonight than last night, so believe fog more likely tonight at 
KBGR than last night.

Fog dissipates quickly Monday morning, with VFR and light winds
expected during the day Monday.

SHORT TERM: VFR conditions expected Monday night through
Wednesday with high pressure firmly in control. Next chance for
MVFR cigs/vis won't be until Thursday as a surface cold front
brings showers to the area.


NEAR TERM: Conditions remaining below small craft. Northeast
breeze up to 15 kt today weakens tonight. No fog.

SHORT TERM: Conditions will remain below small craft during this
period. Confidence has continued to trend down on a tropical
wave moving up the Atlantic coast this week. Currently any
tropical development seems very low, thus not expecting any 
large swells from an offshore system later this week. High
pressure will be the dominate feature over the coastal waters
until Thursday when a weak cold front approaches.





Near Term...VJN
Short Term...Dumont
Long Term...Dumont