Area Forecast Discussion
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FXUS61 KCAR 211335
Area Forecast Discussion
National Weather Service Caribou ME
935 AM EDT Fri Apr 21 2017
Low pressure in southeast Ontario this morning will move across
southern Quebec tonight as a secondary low develops in the Gulf
of Maine. The secondary low will pass south of Nova Scotia
Saturday evening. Weak high pressure builds into the region
Sunday. A cold front will cross the region Sunday night.
.NEAR TERM /THROUGH TONIGHT/...
915 am update...
Today`s primary concern is snowfall tonight into Saturday
morning. The latest analysis and guidance led to a slight
decrease in overall amounts, but the forecast remains on track
for rain to change to snow overnight. Residents in Aroostook
County will likely awake to another white landscape and trace
amounts of snow can be expected as far south as Bangor and
Calais. Amounts will be very elevation dependent with totals
above 3 inches at elevations above 1000 ft in northern zones.
Do not anticipate the need for any advisories at this time.
Prev discussion blo...
Low clouds continue acrs most of the CWA tonight especially in
Downeast zones. Clds are fairly thin acrs the far north and this
has resulted in ocnl dense fog under clr skies in the St. John
Vly. Stratiform rain is lifting northeast into srn New England
attm in area of upglide/warm advection.
Sfc low responsible for overrunning is located in the central Great
Lakes and wl track east twd the Ontario/Quebec brdr this mrng.
Upr lvl low is rotating thru Ontario this mrng and with height
falls off to the northeast expect that it wl continue to head
off to the northeast thru the day. As it does so expect that
pcpn wl mv into wrn zones arnd daybreak.
Most of the forcing from the upr wv wl bring steady rain or snow
into nrn zones late this afternoon thru the ovrgnt. Temps wl
cool enuf to bring accumulating snow to the north with btwn 1-3
inches of snow expected to the north of a Dover-Monticello line
with temps on Fri night dropping into the lwr 30s. Snow ratios
look to drop from about 5:1 in the evening to 8:1 twd daybreak
so this wl be another round of heavy, wet snow.
Further to the south acrs Downeast with vry little frcg expected
as main lows go to the north and well south of the area this
area wl lkly experience low clds, drizzle, fog and ocnl lgt rain
thru the bulk of the aftn and nighttime hrs.
.SHORT TERM /SATURDAY THROUGH SUNDAY/...
The weekend starts cold and unsettled as a secondary low takes
shape in the southern Gulf of Maine Saturday morning and passes
just south of Nova Scotia Saturday evening. The mid and upper
level low will move across the area Saturday night. Brief
ridging builds across the area Sunday morning, but a cold front
will approach the Saint Lawrence River valley by Sunday evening.
Saturday starts with snow across northern areas, especially from the
Katahdin Region north through the Saint John Valley. There will
likely be a mix of rain and snow to the south of the Katahdin
Region to the Bangor area, with mostly rain along the coast. The
snow may continue to accumulate through at least late morning
or midday across northern areas. The afternoon remains cloudy
and damp with a rain and snow in the north and rain in the
south. Model soundings in the north indicate any above freezing
layer is confined to the lowest several hundred feet, so wet
snow will remain favored over rain in the north. Highs Saturday
will be unseasonably cold with highs only in the mid to upper
30s across the Crown of Maine to around 40 degrees in the
Greater Bangor Region. The models and model soundings indicate a
lot of low and mid level moisture, so it will remain cloudy
Saturday night. An isolated snow shower can`t be ruled out with
the residual moisture and upper trough working across the area.
Clouds early Sunday will give way to breaks of sunshine, but an
increase in clouds are expected late in the day across northwest
Maine in advance of the cold front. The air mass moderates
Sunday and high temperatures will be about 10 degrees milder
than Saturday ranging from the mid 40s north to the low 50s
across interior Downeast Maine.
.LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/...
A cold front will work across the area Sunday night with rain
showers in the north that will likely end as some snow showers
overnight with any snow accumulation to likely be an inch or less.
It appears that most of the shower activity falls apart before
reaching the coast. High pressure builds into the region Monday
with dry weather, but with below average temperatures temperatures
in the north with highs mostly in the low to mid 40s. Temperatures
will be more seasonable in the south with highs in the mid 50s in
the Bangor Region. The dry weather will continue into Tuesday with
some increase in clouds from the south as low pressure develops off
the Virginia Coast. Moisture associated with this low may work
north into the area Tuesday night into Wednesday, but the air
mass will be mild enough that any showers will take the form of
rain an and not snow. The models differ on the track of the low
and whether there are just a few glancing showers or some
steadier rain. The last two runs of the ECMWF remain the most
aggressive and the ECMWF is the odd model out at bringing
steadier rainfall to the region. An upper trough following the
low passage could bring a few more showers to the area Thursday.
.AVIATION /14Z FRIDAY THROUGH TUESDAY/...
NEAR TERM: IFR across southern terminals this morning with cigs
lifting to MVFR by mid-afternoon. Light rain expected for a few
hours this morning before drizzle develops this afternoon and
Northern terminals will see IFR intially then MVFR by mid-
morning. A mix of rain/snow moves in around 00z before becoming
all snow between 02 and 03z and continuing into Sat morning.
SHORT TERM: Unsettled Saturday with snow north and rain south
with widespread IFR and potentially LIFR Saturday. Mostly MVFR
Sat night into Sun morning with the potential for improvement to
VFR by afternoon. MVFR and local IFR Sun night at the northern
terminals as rain showers and possible later night snow showers
move across the area. Predominately VFR Sun night at the
Downeast terminals. VFR should return to all terminals across
northern and eastern Maine Monday.
NEAR TERM: Conditions will become marginal for SCA level this
evening and through the overnight. Confidence is not high enough
to issue a small craft advisory at this time though it may be
SHORT TERM: The wind and seas will be close to small craft advisory
levels Sat into Sat eve as low pressure passes south of the
waters. The wind will diminish and the seas will subside Sunday
with conditions to remain below small craft advisory levels
Monday and Tuesday.