Winter Storm Orlena Update One
000
FXUS61 KCAR 310510
AFDCAR
Area Forecast Discussion
National Weather Service Caribou ME
1210 AM EST Sun Jan 31 2021
.SYNOPSIS...
High pressure will build toward the region overnight, then
cross the region through Monday morning. Low pressure will
approach from the south Monday, and track northeast into the
Maritimes by Wednesday. High pressure will build in on Thursday.
&&
.NEAR TERM /THROUGH SUNDAY/...
12:10 AM Update: A three dog night across the FA as temperatures
tumble under a clear sky. Some clouds may try to back into far
northeast Maine toward daybreak, but this will be too late for
any impact on our low temperatures. The temperature is down to
16 below at Estcourt Station and Big Black River as of midnight.
Made some tweaks to lower the hourly temperatures and overnight
lows. The broad northwest valleys will likely drop into the 20
to 25 below range overnight with the potential that some spot in
the FA ends up with the contiguous U.S. cold spot.
Previous Discussion... High pressure will continue to ridge
down across the area from the north on Sunday with partly/mostly
sunny skies across the region. Afternoon high temperatures will
range from around 20 degrees across the north and low to mid
20s central and Downeast.
&&
.SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/...
High pres will drift across eastern Canada Sunday night into Monday
w/cold air damming setting up. Low pres moving across the Ohio River
Valley will weaken during the day on Monday w/energy in the upper
levels being transferred to the Delmarva. This in turn will allow
for secondary development as the energy diving down the backside of
the upper trof will lead to rapid intensification as the low
lifts ne. In the meantime, Sunday night looks to be chilly night
w/some areas seeing temps below zero w/that high to the n
keeping thicker clouds at bay. Some areas such as the Allagash
and North Woods, could be seeing readings apchg -5F or perhaps
even colder. Light winds, mostly clear skies and snow cover will
be a good setup for it. Monday will see increasing clouds which
will aid in halting temps back a biT, but still above normal
for the beginning of February.
Monday night into Tuesday will feature clouds continuing to thicken
with snow lifting into the srn areas later at night, and then
gradually lift up across central and then into northern areas
on Tuesday. The latest runs of the model guidance including the
GFS/NAM and ECMWF appear to have shifted the low further e,
which in turn keep colder temps in, allowing for more snow as
far s as the coast. There are some timing and placement
differences, but a good swath of the individual ensemble members
of the GFS and ECMWF point to the potential for a sanguined, if
not major storm. Negatively tilted trof, upper difluence and
strong upper level jet leading to strong intensification.
Tapping of Gulf and Atlantic moisture being pulled into the NErn
US. There is potential for some heavy snowfall rates on Tuesday
w/strong deformation possibly setting up, especially later in
the day continuing into Tuesday night. More on that below. There
is still some risk of snow going to rain especially for the
coast and extreme eastern Washington County as some warmer air
gets pulled into coast. Despite the latest shift in the track by
the model guidance, preferred to stay w/consistency and kept
the threat for a changeover to rain later in the day on
Tuesday/Tuesday evening. If the trend continues for a track
over the Gulf of Maine waters, then the rain-snow line may need
to be shifted further s. Sleet is also concern as GYX pointed
out the warm layer at 850- 700mbs coming w/this strengthening
system, which the ECMWF shows being prolonged. This would lead
to a significant accumulation of sleet. After coordinating
w/GYX, decided to keep the mention of sleet out of the forecast
for now given it is 5-6th period. As if to add to the mix, winds
are also a concern especially across the Downeast region w/llvl
jet of 50+ kt from the ENE. This could only hamper things
especially if heavy snow sets up w/whiteout conditions a
possibility if this setup is realized.
One last item is the potential for some splashover at the time
of high tide given the prolonged ENE wind into Tuesday night.
Seas building to 10-12 ft w/in the 20 foot zone could allow
large breakers leading to the splashover.
&&
.LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/...
Snow, heavy at times w/some sleet Tuesday night w/some high
snowfall rates(possibly 1-2"/hr), especially across the Maine
Central Highlands into Northern Maine. The intensifying low
looks like it through the Bay of Fundy which is a good marker
for heavy snowfall across the region especially northern areas.
The snow is expected to gradually wind down on Wednesday from s
to n, w/far northern areas seeing snow continuing into the early
afternoon, before winding down. A foot or more snow is possible
across Northern and portions of the Maine Central Highlands.
Remaining unsettled into Thursday as the upper trof swings
across the region leading to clouds and flurries. A break early
Friday w/some weak ridging and partial clearing. This will
short-lived as a weak system lifting across the region could
bring some light precip in the form of snow to the region, w/the
highest percentages across Downeast areas. The beginning to the
weekend looks to be rather dry per the ECMWF guidance, while
the GFS is more aggressive w/the next system and threatens to
bring snow/rain to the region. Attm, it does not look like
anything too heavy. High confidence that temps will average
above normal during this stretch.
&&....
posted by Advackia at 11:26 PM
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