Area Forecast Discussion
Issued by NWS Caribou, ME

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FXUS61 KCAR 280117

Area Forecast Discussion
National Weather Service Caribou ME
917 PM EDT Tue Jun 27 2017

An upper level trough will remain to our west through mid week.
Weather disturbances moving out of the trough will cross the
overnight into Wednesday. A larger area of low pressure may
approach late Thursday.


9:17 PM Update...Showers and thunderstorms continue to lift
northeast across portions of the CWA. Most of the thunderstorm
activity at this time is confined to northern Penobscot and
southeast Aroostook Counties. The main threats with these storms
are heavy downpours and dangerous cloud to ground lightning.
The threat of hail and wind have both diminished over the past
couple of hours. Will update mainly the PoP/Wx grids based on
the latest radar and lightning trends, and will continue to
mention heavy rain until around 06Z. Otherwise, updated with the
past few hours of observed data and made some minor adjustments
to the other forecast elements.

Previous Discussion...
Radar showed activity filling in as the upper s/wv lifts up
across the region as seen on the latest satl wv imagery. 18Z
surface analysis showed area of mid to upper 50 dewpoint air
nosing up into the eastern side of the CWA while lower 50
dewpoints hold back to the west. Expecting the column to moisten
more as shown by the latest RAP and NAM. Jet streak of 30-35 kt
noted at 925 mbs to lift n into the evening to provide lift.
Llvls have warmed enough thanks to sunshine returning.
Atmosphere will destabilize more into the evening allow to tstms
to fire. Cold temps aloft(-20c at 500 mbs) will allow for the
potential for hail and inverted type sounding will lead to some
strong wind gusts. Associated cold front is expected to lift
across the region later in the evening into the overnight
period. Hail potential still a threat but things appear to shift
to strong winds gusts as noted by the latest HRRR and very
heavy rainfall. Storms moving over areas that have been hit
earlier could lead to some localized flooding. Added patchy fog
w/the sse flow expected overnight and moist blyr.

The cold front continues to slide across the area on Wednesday
w/more action setting up for the day. There looks like there
could be a reprieve in rainfall through mid morning. Another
round of shower activity expected later by the afternoon. Steep
lapse rates around 6.5 c/km and CAPE of 400-700 joules will
allow for the threat for tstm. This activity will be fueled by
the upper level trough swinging across the region. Once again,
the risk for some hail and gusty winds is there but at this
point, confidence is low and decided to leave out enhanced
wording for now. Daytime temps will be somewhat similar to today
w/upper 60s to lower 70s. As pointed out by the midnight crew,
well below normal for late June.


The upper trof will exit through the Canadian Maritime
provinces early Wednesday evening followed by partly to mostly
cloudy skies. Lows will drop back to the low 50s north and mid
to upper 50s downeast. The next in a series of upper impulses
will cross the region Thursday with a more showers and chance
for thunderstorms mainly across the north. Unsettled weather
continues Thursday night and as a warm front lifts north of the
region. Expect mainly cloudy skies with the chance for showers
and thunderstorms. Friday will continue unsettled with more
showers and thunderstorms expected as a cold front crosses the
region from the northwest. High temperatures both Thursday and
Friday are expected to be near normal in the low to mid 70s,
except cooler along the coast.


The cold front will stall out across central portions of the
region Friday night and then begin to move back north as a warm
front Saturday and Saturday night. This will continue the
unsettled weather pattern with the chance for showers and
thunderstorms. Showers and thunderstorm chances continue on
Sunday as a cold front moves across the region. It finally looks
like a drier weather pattern may finally be in the offing next
week as a large ridge of high pressure builds toward the region.
High temperatures will be close to normal through the period.


NEAR TERM: Mostly VFR this evening, but with brief IFR in
heavier showers and thunderstorms. Conditions across the region
will likely lower to IFR late tonight w/lower cigs and vsby due
to some fog. Improvement to MVFR and even VFR early Wednesday
and then a drop back to MVFR and perhaps IFR by afternoon w/the
showers and possible tstms.

SHORT TERM: The main story with regard to aviation weather will
be the potential for showers and thunderstorms Friday right
through Sunday. Overall most of the time will remain VFR
outside of possible MVFR or even lower conditions in any times
of showers and thunderstorms.


NEAR TERM: No headlines anticipated through the period. Some
elevated convection expected overnight w/some fog to limit vsbys
at times. Winds expected to remain around 10 kts w/seas around 3

SHORT TERM: A small craft advisory may be needed mainly for
seas Friday into the upcoming weekend.





Near Term...CB/Hewitt
Short Term...Duda
Long Term...Duda
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