Scientific Forecaster Discussion
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Area forecast discussion
National Weather Service Caribou ME
255 am EST Mon Nov 20 2017
high pressure will build to the south of the region today, and
move well southeast of the area by Tuesday. A warm front will
lift north across the area Tuesday. A cold front will cross the
area Wednesday, and will usher a colder air mass into Maine for
Near term /through tonight/...
much colder and breezy today with flurries across the north and
Surface high pressure will slowly build over the northeast today and
tonight while an upper trough digs into the region. This latter
feature will bring increasing clouds through the day, along with
some flurries, mainly across the higher terrain in the North Woods
and northern Aroostook County. Cold air advection aloft will allow
for good mixing in spite of the cloud cover, so anticipate gusty
west winds by this afternoon. Skies will gradually clear out later
today into tonight as the high crests over the region and the upper
trough moves to our east. Temperatures will be well below normal;
highs will only be in the mid 20s to lower 30s today, while
tonight's lows will be in the teens.
Short term /Tuesday through Wednesday/...
an upper trough will dig into the western Great Lakes Tuesday as a
surface low passes south of James Bay and into western Quebec.
A surface high will retreat well off the middle Atlantic coast.
This will set up a return southwest flow of much milder air into
the area. The 850h temperatures are expected to warm 15-18c
between 00z Tue and 00z Wed, and will likely be above 0c across
all but the northwest corner of the County Warning Area by late in the day
Tuesday. As a warm front lifts across the region Tuesday it will
be accompanied by a mid level deck of clouds that should clear
out of the downeast region by around midday, but may hold until
sunset in the far north. Highs Tuesday are expected to be about
10 to 15 degrees (f) warmer than Monday, with the most warming
noted downeast where there should be more sunshine. Highs are
expected to range from the mid 30s in the Saint John valley and
from 45 to 50 degrees toward the coast.
The upper trough moves east Tue night and Wednesday with the trough
axis moving into Maine by late Wed. A surface low is expected
to lift into northern Quebec with the first in a series of cold
fronts to work across the area with a few snow or mixed rain and
snow showers across northern and central portions of the County Warning Area.
Rain from a southern branch low will likely spread across
downeast areas during the late morning or midday hours, with
the best chance of rain along and near the coast and into
central Washington County, with Bangor perhaps just on the edge
of the steady rain. There are still model differences with the
NAM and GFS brushing the area, and the Canadian and European model (ecmwf)
bringing the precipitation much further north and west. Until
there is better agreement and higher forecaster confidence will
stick close to the ongoing forecast during the day Wednesday,
but will increase the pops a bit more across the downeast region
where there is fairly high confidence that it will rain from
late Wednesday morning into Wednesday evening.
Long term /Wednesday night through Sunday/...
as the southern branch low and trough pull away from the region
Wednesday night there remains uncertainty as to how much
moisture may warp back into eastern Maine during the evening.
There is the chance that there could be a couple of inches of
wet snow on the backside, but forecast confidence is lacking due
to the differences in the track of the southern branch low.
There is high confidence that much colder air and a secondary
cold front crosses the area Wed night ushering a colder air mass
back into the region with some flurries and isolated snow
showers in the north and west. Thanksgiving day looks dry and
cold with highs about 5 degrees below average, and ranging from
the upper 20s in the Saint John valley to the mid 30s in the
greater Bangor region. Another upper level trough and cold front
work across the region later Thu night into Fri with clouds and
isolated to scattered snow showers, mainly across the northwest
half of the County Warning Area. A longwave trough digs into the northeast U.S
over the weekend with another cold front to work across the
area Sunday. There will likely be rain and snow showers around
Saturday and snow showers Sunday, but at this time there does
not appear to be any phasing of the north and southern branches
of the jet, and no indications of any coastal lows.
Aviation /08z Monday through Friday/...
near term: VFR conditions will prevail through tonight,
particularly at the southern terminals. Flurries or light snow
showers are likely at the northern sites through early this
afternoon, which may bring occasional MVFR visibilities or
Short term: a mid deck of clouds will move north across the area
Tue, but VFR conditions are expected. MVFR expected in rain and
snow showers at the northern terminals Wed, with conditions to
likely lower to IFR and perhaps LIFR in rain and fog at the
downeast terminals Wed afternoon. Conditions should improve to
VFR by late Wed night or early Thursday morning with VFR Thu
into Thu evening with possible MVFR by late Thu night at the
northern terminals where there will be the chance of snow
showers. VFR expected Fri at the downeast terminals with MVFR at
the northern terminals where there will be more clouds and a
continued chance of snow showers.
near term: both the Gale Warning for the outer waters and the Small
Craft Advisory for the inner waters have been extended out through
this evening. Winds will abate a bit this morning, and gusts may
only be 30 kt or so over the outer waters for several hours.
However, winds will increase again this afternoon and evening before
lessening late tonight as high pressure builds over the waters.
Therefore, extending both headlines seems appropriate. Seas will
remain in the 6-10 ft range through much of the period, then subside
late tonight as winds decrease.
Short term: Small Craft Advisory conditions are expected
Tuesday. The wind will diminish Tue night, but the seas will
likely remain above 5 feet on the coastal waters. Conditons may
finally lower to below Small Craft Advisory levels during the
a record 0.77" of rain fell at Caribou, Maine yesterday. This
breaks the daily record for 11/19 of 0.67" set in 1968. This was
the weakest daily precipitation record for the month of
Marine...Small Craft Advisory until 1 am EST Tuesday for anz052.
Gale Warning until 1 am EST Tuesday for anz050-051.