Scientific Forecaster Discussion
fxus61 kcar 101730
Area forecast discussion
National Weather Service Caribou ME
1230 PM EST Sat Dec 10 2016
cold high pressure will build across the region through tonight
then move out into the Atlantic on Sunday. Low pressure from the
Great Lakes will approach Sunday night, redevelop along the Maine
coast on Monday, then move east of the Maritimes on Tuesday.
Near term /through Sunday/...
1230pm update: no major changes. A subtle upper trough is sparking
snow showers towards northern Aroostook as the Arctic air becomes
more entrenched into the area. Increased pops slightly in that
area as the expected flurries are now adding up to a trace of
Orgnl disc: latest radar ref vol scans show whats left of
streamer sn bands ovr east cntrl ME slowly weakening and movg E into
New Brunswick prov. We will keep a mention of sct flurries and isold sn shwrs
for the north and east cntrl ptns of the region at least thru the morn,
then diminish cvrg durg the aftn. With increasing subsidence
descending from Alf, any new sn shwr band will not likely have
enough cld depth to produce much in the way of sig sn rates, so
little if any accumulation is xpctd tdy.
Otherwise, skies will be ptly cldy north and cntrl and msly sunny
downeast tdy with brisk northwest winds, producing ind chills of zero to
10 below across the north and cntrl and single digits abv zero
downeast with slight moderation of these values this aftn. With
the apch of the sfc high pres from the west tngt and lesser winds
Alf, winds should diminish spcly by late ngt. Fcst cld cvr will be
tricky, with models indicating some mid/low lvl cld cvr associated
with a weak S/WV Alf movg east into spcly nrn ptns of the region
later tngt, likely limiting radiational cooling potential. For
this reason, we did not go as cold as it would have been if clr
skies were anticipated thru the ngt, with fcst ovrngt low temps
the most uncertain aspect of the near term fcst this update.
Short term /Sunday night through Tuesday/...
high pressure will be moving off the East Coast on Sunday. A
shortwave rapidly moving east in the fast jet stream flow will be
moving into the Great Lakes Sunday. Moisture out ahead of this
system will bring some increasing clouds late Sunday. Clouds will
thicken up Sunday night and snow will spread over the area before
dawn on Monday. Forecast guidance has come into good agreement on a
fast moving, moderate snow event from this system. Snow Monday
morning into midday Monday will change to rain along the coast by
midday. Drier air surging in, in the mid levels, will end
precipitation over central and downeast areas Monday afternoon. Snow
will continue over the north then taper off to snow showers at the
end of the day Monday. Preliminary snow amounts range from around 7
inches over interior downeast locations to 4-5 inches over the far
north. Coastal downeast areas, where the snow changes to rain, will
likely have only a couple inches.
Long term /Tuesday night through Friday/...
low pressure will move away through the Maritimes Monday night with
snow showers continuing over the north and partial clearing
downeast. High pressure will then bring a mostly sunny day downeast
and a cloudy to partly sunny day over the north on Tuesday. Our
focus later in the week then turns to a bitter cold airmass diving
down through Canada. A cold front will come through on Wednesday,
possibly with some snow showers. A frigid airmass will then
overspread the region Thursday into Friday as the Arctic trough
slides across our north. Highs on Friday may remain in the single
digits north to teens downeast. Saturday will remain cold, then a
large area of moisture ahead of a broad trough of low pressure may
bring increasing clouds later Saturday with snow possible late over
the weekend. Arctic air to our north combined with a deep warm
southwesterly flow to our south could result in the set-up for
freezing rain and sleet over parts of the downeast region late in
Aviation /18z Saturday through Thursday/...
near term: mainly VFR conditions are xpctd across the taf sites
tdy thru tngt, with intervals of MVFR clgs likely across nrn taf
sites this morn. Brief MVFR/IFR vsbys are also possible across nrn
taf sites with isold sn shwrs this morn.
Short term: VFR conditions are expected Sunday into Sunday
evening. Conditions will then lower to IFR in snow from south to
north late Sunday night and remain IFR on Monday in snow, and mix
downeast. Conditions may improve to MVFR or VFR downeast Monday
afternoon but remain IFR to MVFR over the north. VFR conditions
downeast and MVFR to IFR conditions over the north are expected
Monday night. Conditions should improve to VFR across the area on
near term: strong Small Craft Advisory conditions with cold advcn northwest winds will
cont thru tdy across all of our waters, then slowly diminish this
eve to below Small Craft Advisory thresholds late tngt with the apch of the sfc hi.
Went a little abv ww3 WV guidance for fcst WV hts tdy, then blend
to guidance for WV hts tngt. Primary WV pds will be arnd 4-5 sec
with secondary swell pds of 9-11 sec thru the near term.
Short term: an Small Craft Advisory will likely be needed Monday for southeast winds
ahead of approaching low pressure. Winds may drop below Small Craft Advisory
Monday night into Tuesday as low pressure moves away.
high tide Monday morning is at 8:35 am in Bar Harbor and 8:44 at
Eastport. Tides will be approaching astronomical high tides with
Monday being the day before the full moon. Onshore flow ahead of
approaching low pressure combined with the perigee tides may result
in high tide levels above normal and possibly some minor splash-over
Marine...Small Craft Advisory until midnight EST tonight for anz050>052.