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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 172010

Area Forecast Discussion
National Weather Service Caribou ME
410 PM EDT Sat Aug 17 2019

Surface high pressure will remain over the region into Monday while
an upper level disturbance moves across the state tonight. A 
weak cold front will move through late Monday followed by high 
pressure for Tuesday. A stronger cold front is expected later 
Wednesday night into Thursday. Canadian high pressure builds
Friday into Saturday.

The primary weather influence through Sunday 
is the large high offshore pumping moist marine air northward 
under an inversion. This is producing low clouds this afternoon,
areas of fog tonight, and more low clouds into Sunday morning. 
A potent shortwave currently moving across upstate New York and
Quebec will be the other big weather maker tonight. Most of the
activity with this system will occur after midnight in this 
forecast area and linger into early Sunday morning.
Even with the loss of daytime heating and movement over stable
low levels, thunderstorms will likely continue into tonight as 
the line moves into Maine. There's decent 0-6 bulk shear and 
elevated CAPE. A strong jet streak moving across the Bangor area
and Downeast Maine could result in some stronger storms after
midnight. The thunderstorms could drop locally heavy rainfall. 
There's a decent plume of higher PWs approaching 1.75 inches 
with the line, a deep warm cloud layer, and even a compact LLJ 
indicated with the line of storms. The deep moisture and 
efficient precip processes could generate up to 2 inches of rain
in an hour. One and three hour FFG are relatively low and 2 
in/hr rates could cause some issues. A good area for prolonged 
heavy showers and training cells would appear to be in northern 
Aroostook County where a very compact upper low will cross late 
tonight into early Sunday morning. As the system departs in the 
morning, it'll leave behind dew points in the mid 60s and Sunday
afternoon temps will rise into the mid to upper 70s as the 
inversion's hold breaks somewhat. The inversion and low clouds 
will persist on the coast for Sunday with continuing onshore 

Unsettled weather with showers and thunderstorms continues 
across Maine through early Tuesday morning as a frontal system 
moves through the area. Higher pressure will bring clearing to 
the area early Tuesday morning and will remain across the area 
through the end of the period. 

Loaded a blend of the GFS/NAM/ECMWF/GEM to smooth out the minor
differences in the models.

A high pressure ridge over the area will be displaced Wednesday
morning by a low and frontal system moving north alone the 
coast. It will move into Downeast Maine Wednesday morning then 
spread north to northern Maine by mid day. It will bring another
round of showers and thunderstorms to the region. The system 
will move east into New Brunswick early Friday morning. A wrap 
around trough will move through northern Maine Friday morning, 
otherwise high pressure will dominate the weather through the 
end of the period Sunday morning. 

Loaded a blend of models to smooth out the minor differences.

NEAR TERM: MVFR cigs will deteriorate to IFR cigs this evening
and then VLIFR is possible after midnight...mostly at BHB and
BGR. Embedded thunderstorms are possible after midnight for all
sites with potentially heavy rainfall and IFR vis. Cigs and vis
will gradually improve towards MVFR Sunday morning...reaching
VFR in the afternoon except along the coast to include BHB.

SHORT TERM: Sunday night through Thursday...Low MVFR to IFR 
conditions in showers and TSTMS through early AM Tuesday.

Early AM Tuesday through early AM Wednesday...VFR. 

Wednesday morning through Thursday...BGR and BHB to Low MVFR to
IFR in showers. Spreading to HUL, PQI, CAR, and FVE by midday. 
Showers and TSTMs after mid morning all sites.

NEAR TERM: Fog continues through the period. Thunderstorms are
possible after midnight tonight. Winds will remain light. A long
period south swell from a storm well south of the Gulf of Maine
will generate seas around 3 feet.

SHORT TERM: Winds and seas below Small Craft Advisory levels 
through the period.


Near Term...MCW
Short Term...Norton
Long Term...Norton