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Area Forecast Discussion (AFD)

Issued by Caribou, ME (CAR)

FXUS61 KCAR 192200

Area Forecast Discussion
National Weather Service Caribou ME
600 PM EDT Mon Aug 19 2019

A cold front will cross the region tonight. High pressure will 
move across the region Tuesday. A cold front will approach later
Wednesday then cross the region Thursday. Another cold front
will cross the region late Friday. High pressure will build
toward the region later Saturday.


6 PM Update: Showers and thunderstorms are moving across the
region early this evening associated with a pre-frontal trough.
The most unstable air is to the south of Millinocket in areas
that broke out of the low clouds this afternoon. The storms to 
the north are run of the mill with brief heavy downpours and 
some lightning. The threat of stronger storms remains to the 
south; however, the threat of severe storms looks to be over 
with at this point and have dropped the severe wording and will 
go with gusty wind and heavy downpours until 8 pm in an area 
south of Millinocket. Otherwise, just minor tweaks based on the 
latest observations.

Previous discussion:
The development of SBCAPE has been very limited due
to persistent low clouds over most of the forecast area. The 
exception has been the far western zones where a line of storms 
along a pre-frontal trough has materialized and will move 
eastward into the evening. As they move east, the storms will 
move over the stable environment and tend to weaken. The 
possible exception will be towards southern Piscataquis County 
and southern/central Penobscot where low clouds finally exit and
a somewhat better combination of CAPE and shear will exist into
the evening. Stronger storms may advect from the more 
productive convective environment in southern Maine without 
weakening. Will maintain the current advertised threats, which 
are mostly heavy downpours in northern zones later this 
afternoon into the evening and potential damaging winds/small 
hail/heavy rainfall around the southern Piscataquis/south- 
central Penobscot corridor. Can't rule out some rotating storms 
based on RAP/HRRR parameters and the low LCL environment. Storms
from this region will weaken as they move towards the 
persistent stratus on the coast and in Washington County and the
overall storm threat will move out of the area by later this 
evening. The actual cold front will enter northern zones this 
evening and ease to the coast by late tonight. This means 
another muggy night with lows in the lower 60s outside of 
northern Aroostook and fog will return to the coast and much of 
the Downeast region. Tuesday looks much better with lower 
humidity, little cloud cover and highs in the lower 80s with a 
dry west wind.


High pressure will begin to exit across the Maritimes Tuesday
night with mostly clear skies across the region. Low pressure 
will intensify across Quebec province Wednesday through 
Wednesday night drawing a warm front across the region later 
Wednesday through Wednesday night. Clouds will increase across 
the region Wednesday, with a chance of mostly afternoon 
showers/thunderstorms. Forecast soundings indicate elevated 
instability with the warm front Wednesday night which will 
support showers/thunderstorms. The warm front should lift north 
of the region early Thursday. A pre-frontal trof, in advance of 
an approaching cold front, will support a chance of 
showers/thunderstorms Thursday. Temperatures will be at near 
normal, to slightly above normal, levels Wednesday/Thursday.


The cold front will cross the region Thursday night with a
chance of early showers/thunderstorms in advance of the front. 
An upper low tracks north of Maine Friday. A disturbance moving 
around the upper low will cross the region along with a  
secondary cold front/trof. Expect a chance of showers across 
mostly the north and mountains Friday. Otherwise, expect 
generally partly cloudy skies. Upper level troffing remains 
across the region Saturday, which could help support a slight 
chance of showers across mostly the north and mountains. High 
pressure then builds across the region later Saturday into 
Monday with partly cloudy/mostly clear skies. Temperatures will
be at slightly below normal levels Friday through Sunday, with 
near normal level temperatures Monday.


NEAR TERM: North of HUL, MVFR cigs will tend to become IFR this
evening and embedded thunderstorms may cause IFR vis in heavy 
rainfall. All these sites will improve to VFR by late evening 
and continue VFR through Tuesday. 

South of GNR and MLT, to include BGR, MVFR cigs will improve to
VFR but strong, potentially severe, thunderstorms will cross 
late this afternoon into the evening. VFR conditions follow for 
these sites through Tuesday. 

Towards the coast, to include BHB, IFR cigs will deteriorate to
LIFR and IFR vis in fog this evening. The fog will break late 
tonight, giving way to VFR on Tuesday.

Tuesday night...VFR.

Wednesday...Generally VFR. Occasional MVFR possible late with
a chance of showers/thunderstorms.

Wednesday night through Thursday night...Variable conditions
with showers/thunderstorms. Fog possible mostly along the 
Downeast coast. 

Friday through Saturday...Generally VFR. Occasional MVFR
possible across the north and mountains.


NEAR TERM: Fog continues through tonight and then moves
southward out of the waters late tonight into early Tuesday.

SHORT TERM: Winds/seas will remain below small craft advisory
levels Tuesday night through Thursday. Showers/thunderstorms are
possible Wednesday afternoon through Thursday. Visibilities
could be reduced in fog Wednesday night through Thursday.





Near Term...CB/MCW
Short Term...Norcross
Long Term...Norcross