FXUS61 KCAR 172246
Area Forecast Discussion
National Weather Service Caribou ME
546 PM EST Sat Nov 17 2018
A cold front will track across the region tonight. High
pressure moves over the area Sunday and moves east Sunday night.
A weak area of low pressure is expected to move up across the
Gulf of Maine on Monday.
.NEAR TERM /UNTIL 6 AM SUNDAY MORNING/...
530 PM Update: Adjustments were made to fcst cld cvr (from
latest sat imagery) and PoPs this eve into the ovrngt as a
weakening cold front crosses the FA ovr the next 3 to 9 hrs. We
cannot rule out isold-sct sn shwrs ovr the wrn highlands, but
most lctns across Nrn/Cntrl ptns of the FA will likely see sct
flurries at most. Lastly, fcst hrly temps/dwpts were adjusted
thru the ovrngt from latest sfc obs. Most of the temp fall
needed to reach fcst daybreak lows will have to occur post
frontal passage late tngt when skies clr.
Orgnl Disc: Clouds holding on and will continue to do so into
the evening. Weak waa in place attm w/pre-frontal trof moving
across the region. Temps into the low/mid 30s north and central
areas while upper 30s to lower 40s from the Bangor region to the
coast. Some flurries/light snow showers popped up across the n
and w but mainly isolated in coverage. Deep moisture in place
from 925-700mbs per the LAP/RAP soundings. This is confirmed by
the 12Z UA and latest obs. The 12Z NAM is showing some potential
for snow shower activity to develop ahead of the apchg cold
front later this evening through around midnight or so. Some
decent caa noted on the UA as well as the NAM. Steepening llvl
lapse rates(7.0+ c/km) w/CAPE OF 40+ joules could lead to some
snow showers and perhaps a brief squall. The area for the
highest threat for this activity will be across the Maine
Central Highlands and the Mt. Katahdin region. The RAP guidance
is similar to the NAM but its placement is different w/any
activity further s. Attm, decided to add 20-30% for snow showers
in the aforementioned areas. Any snowfall accumulations will be
trace amounts to a few hundreths. Temps will be held up through
midnight until the cold fropa. There does appear to be enough
of a pres gradient to keep winds around 5 mph or so. This will
offset any dramatic cooling. As a matter of fact, the best
chance for cooling will be across the Bangor region and interior
Downeast as some clearing is expected w/the wnw wind.
Therefore, overnight temps were brought up from the previous
forecast especially for the north-central and western areas.
High pres set to ridge across the region on Sunday w/mostly
sunny skies and and light winds. It will be cooler than today
and well below normal
.SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/...
Forecast confidence remains below average for this time with
periods of rain/snow on the coast and snow further inland.
Generally pattern will remain broad cyclonic 500mb flow over the
state. The first wave to bring the chance for snow to the area
is still the Monday morning weak coastal low which could bring a
few inches to the coast, but air temps are expected to get above
freezing so any snow that does fall could melt. Timing wise
though, there could be some slick roads for Monday morning
commute. Next forecast issue is the Tuesday wave with large
spread continuing in guidance, although some increased consensus
expected the ECMWF remains an outlier with no snowfall. Looks
like there will be a broad elongated inverted trough across the
state with mid-level convergence. Due to the lack of consistency
when with a superblend approach on pops and qpf. Will have to
see if things iron out on this wave in the next 24hrs.
.LONG TERM /TUESDAY THROUGH SATURDAY/...
Record Cold Possible for Thanksgiving...
General cyclonic flow expected for this period with an arctic
boundary to impact the region Wednesday or Wednesday night.
Could be snow showers and gusty winds with this front during a
busy travel period, will have to watch this. Confidence is still
high for a blustery near record cold Thanksgiving with a very
anomalous airmass pushing into the areas. Wind chill values on
Thanksgiving day could stay below zero for some areas with a
strong NW wind, it will not be a pleasant day for an outside
walk. Quiet weather is finally expected at this time for Friday
and Saturday, with a moderating airmass.
.AVIATION /00Z SUNDAY THROUGH THURSDAY/...
NEAR TERM: Mostly VFR conditions are expected. Isolated snow
showers are possible with a cold front late this evening...mostly
towards GNR. There could be a brief period of MVFR this evening
for the northern TAF sites.
SHORT TERM: Potential tempo IFR conditions by Monday for
KBGR/KBHB with light snow causing low cigs and vis. Confidence
is still low on this wave. Another low confidence coastal rain
and interior light snow event could impact the region on
NEAR TERM: Decided to pull the intra-coastal zone out of the
SCA. Extended the SCA for the outer zones through 4 am Sunday.
Winds will pick up w/the cold fropa and gusts to 25 kts are
expected. Those winds will drop off on Sunday as high pres moves
in from the w. Seas were running high today averaging 7-9 ft
which was much higher than what the local wave guidance
predicted. A south swell w/a period of 11 seconds helped keep
those seas up. Decided to blend in the NAM Swan guidance as it
was initializing close to reality at 18Z. This guidance shows
the seas dropping back overnight into Sunday as the swell
SHORT TERM: After an active 2 week period no SCA conditions are
expected over the coastal waters Monday through Wednesday. An
arctic cold front will cross the waters on Thursday bringing
potential SCA or higher conditions.
MARINE...Small Craft Advisory until 4 AM EST Sunday for ANZ050-051.
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