End of November Winter Storm Update One

000

FXUS61 KCAR 290346

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

1046 PM EST Sun Nov 28 2021

.SYNOPSIS...

Low pressure will develop south of the Gulf of Maine tonight, track

north across Nova Scotia Monday, and continue north across the Gulf

of Saint Lawrence Monday night into Tuesday. High pressure will

build south of the area Wednesday. Low pressure will track to our

north on Thursday followed by a strong cold front Thursday night and

Canadian high pressure Friday.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...

Update...

Surface high pressure will ridge toward the region overnight.

At the same time, an approaching upper level trof will help

support the development of low pressure south of the Gulf of

Maine. Based on satellite trends, have increased cloud cover

across the forecast area overnight with this update. Expect

partly/mostly cloudy skies across the region overnight. Across

Downeast areas, could also have a chance of light snow late,

mostly toward the coast. Any snow accumulation overnight will be

less than an inch. Low temperatures will range from the upper

single digits to the lower teens north, to around 20 to the mid

20s Downeast. Have also updated to adjust for current conditions

along with overnight temperatures.

Previous Discussion...

Low pressure will take shape southeast of Southern New England

late tonight and track from there north across Nova Scotia on

Monday. We will be on the western fringe of this system. The NAM

continues to indicate that enough moisture may back around the

western side of the storm to bring an inch or two of light snow

to eastern areas while the GFS, ECMWF and Canadian models have

the whole system too far east to bring us anything except for a

very light accumulation in eastern Downeast areas. The low will

continue north through the Maritimes Monday night with any light

snow or flurries along the eastern edge of our forecast area

tapering off late at night. The low will intensify bringing an

increasing northwest wind overnight and pulling colder air into

the area as the sky begins to clear late at night from southwest

to northeast.

&&

.SHORT TERM /TUESDAY THROUGH WEDNESDAY NIGHT/...

Low pres will be pulling off to the Maritimes Tuesday morning

w/the western edge of the snow band along the western NB-ME border

shifting to the east. The 12z NAM along w/the ECMWF show some

llvl convergence holding on w/some minor additional accumulation

right along the border through late morning. Things will clear

out into late afternoon a WNW breeze of 10-15 mph. The W wind

coming off the Laurentians could lead to some snow showers for

the western areas as well as portions of the St. John Valley and

Baxter State Park region into the early evening. The activity

shuts down later in the evening as weak high pres ridges across

the region w/some brief clearing and lighter winds. This will

lead to a cold night w/overnight lows in the mid/upper teens

down into the central areas, while downeast seeing lower 20s.

Areas across the nrn tier into the N Woods could see some

readings in the single numbers w/the snow cover.

The clearing looks to be short lived as clouds move in later at

night ahead of upper disturbance slated to move across the

region on Wednesday. This feature appears to be starved for

moisture and best forcing appears to be across the w and nw

areas. Stayed close to the daycrew`s thinking of 20-30% pops

across nrn 3rd of the CWA. Milder w/afternoon high temps getting

into the 30s all the way to the nrn ME border. High pres to the

s ridges across the region Wednesday night w/brief partial

clearing, but increasing clouds once again as the next system

apchs from the w. Temps will bottom out early, and then level

off a WAA and clouds take hold after midnight.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...

As stated by the midnight crew, a fast moving, clipper type

system is forecast to move across the region Thursday into

Thursday evening. This system looks like it will bring a round

of snow to the region initially on Thursday, and then as the

warmer air pushes n, snow will change to rain by late morning

for the central and downeast region, while northern areas will

hang on to some snow longer. The 12z mdl guidance including the

ECMWF and Canadian show the rain-snow line getting pinched from

about the Limestone back into the Chamberlain Lake region of N

Piscataquis County. N of that line, precip looks to stay all

snow w/measurable snow. The GFS and some of its ensemble

members show a warmer solution warmer air(rain/snow line)

pushing all the way to the nrn border. Attm, leaned closer to

the ECMWF and Canadian solution w/the latest NBM supporting this

setup. Colder air to swing back into the region Thursday night

w/rain changing back to a period of snow or snow showers before

ending late at night. The ECMWF and Canadian and their

respective ensembles show portions of nrn and wrn areas seeing

up to 4" of snow before ending. It will be interesting to see

how the later runs treat this upcoming system.

Friday will be much colder and rather windy w/a WNW wind of

10-20 mph and higher gusts as the upper trof swings across the

region. Plus, snow showers and streamers possible possible

during the day. Much colder for Saturday into Sunday w/high pres

building in from the w. Daytime temps both days look to be

below normal for 1st week of December.....