Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 230434

Area Forecast Discussion
National Weather Service Caribou ME
1234 AM EDT Tue May 23 2017

An occluded front will cross the region late tonight. Weak high
pressure will then return across the region Tuesday and
Wednesday. Low pressure will approach from the southwest later


1220 AM Update: Just minor chgs to fcst PoPs, cld cvr, temps and
dwpts into the late ngt based on latest trends of radar ref, sat
imagery, and sfc obs. Otherwise the main gist of the prev fcst
updates remains the same.

Orgnl Disc: An amplifying upper ridge that kept the area dry
today will slide east this evening and a weak occluded front
will enter the area with shower activity. Most of the showers
will cross the region before 2am and precipitation will become
light rain and drizzle as the occlusion draws closer late
tonight. Overall precipitation amounts will generally be near a
tenth of an inch. There had been some expectation that coastal
areas could see up to a quarter inch with a low pressure system
developing along the front, but that low is now expected to pass
much further south of the state during Tuesday...and is no
longer a factor in the forecast. There is some marginal upper
level instability towards the Saint John Valley after midnight,
but not strong enough to prompt mention of isolated
thunderstorms at this point. A drying southwest wind will follow
the occlusion tomorrow morning. This will lift low clouds
fairly quickly tomorrow and allow highs in the upper 60s to low
70s. Some afternoon sunshine is probable with just some fair
weather cumulus. Even areas closer to the coast should warm
up...and have used bias- corrected guidance to compensate for
models keeping it too cool along the coast. The upper low
associated with the occlusion is expected to fill quickly and
ride well north of the area. With the resultant weak ridging
aloft and at the surface, did not feel compelled to include any
afternoon showers.


Models` slowing trend continues regarding rain onset for next
event. Looks like rain will hold off until late Thursday at
least, probably beginning Thursday night. Weak ridging aloft
Tuesday night to Thursday, with a gradual shift from low level
offshore to low level onshore flow. Temperatures near average.
Generally partly cloudy, becoming mostly cloudy Thursday as
moisture begins to increase from the southwest ahead of next


Likelihood of rain Thursday night to Friday as a decent upper
level low moves through with a likely surface low in the Gulf of
Maine. Enough models and ensembles have the rain that opted to
bump up precip chances some for the event, with 80 percent PoPs
from central to Downeast. Event has the potential to produce in
the neighborhood of an inch of rain. No threat of snow. Also,
any threat of thunderstorms looks minimal.

Cooler air moving in behind the system Friday night, although
there`s a fair amount of uncertainty in how cool the airmass is
behind the system. If the colder range of possibilities
transpires and everything works out just right, can`t rule out
frost Saturday night. Weekend looking mostly dry.

Next rain chance is around Monday.


NEAR TERM: MVFR at BGR and BHB before lowering to IFR after 02z. VFR
across the north through about 03z tonight before lowering to
MVFR as -ra moves in from the west. Conditions will lower to
IFR between 04 and 06z and persist until after daybreak when
weak front goes through. VFR returns to all terminals late
morning with exception of BHB.

SHORT TERM: VFR Tuesday night through Thursday inland. From
Bangor to Coastal Downeast, potential for MVFR/IFR ceilings from
marine layer late Wednesday night into Thursday. Widespread IFR
likely Thursday night into Friday with the next rain event.


NEAR TERM: The only two issues of note will be some fog rolling
in later tonight through Tuesday morning and a gradually
increasing south swell that could reach near 3 ft by late

SHORT TERM: Small craft conditions possible Thursday and Friday
with the next system. Before then, below small craft.





Near Term...VJN
Short Term...Foisy
Long Term...Foisy
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