Early December Storm Update One

261

FXUS61 KCAR 120309

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

1009 PM EST Wed Dec 11 2024

.SYNOPSIS...

Intensifying low pressure will track west of the region

tonight, then lift north across Eastern Canada Thursday. High

pressure will build in for Friday through the weekend. Low

pressure will approach from the west on Monday.

&&

.NEAR TERM /THROUGH THURSDAY/...

10 PM Update (MS):

The latest surface analysis shows a deepening 992mb low over the

Saint Lawrence Valley, with a surface trough extending south

through NH into southern New England. The 850mb LLJ continues to

intensify and is currently analyzed over 80kt along a line

extending south from just west of Bangor to Cape Cod. The jet

will continue to intensify and pivot eastward, leading to

widespread damaging winds, particularly across Downeast and

coastal areas where gusts exceeding 70 mph are possible. The low

level jet has brought in warmer air than previously anticipated,

and Bangor has tied their record high temperature of 59 degrees.

Rapid snowmelt north of Bangor, combined with heavy rain, areas

of dense fog, and strong winds, will make travel difficult

overnight. Poor drainage flooding of roads is expected. No

significant changes were needed with this update, aside from

raising temperatures to match observations.

Previous Discussion:

The large low pressure system will continue

to track the center across the west this evening and bring the

cold front through the region tonight.

Winds: The low level jet will push in from the south, over the

waters, and into the Downeast coast which will increase S flow

this evening. Before midnight, winds will increase drastically

with the cold front approaching the region. The main areas of

concern will the the coastal and interior Downeast and the

Bangor Region. This is due to the S flow and the history of S

progressing through the Penobscot bay and river causing impacts

in Bangor. Around midnight, the low is expected to intensify,

causing the front to pick up speed and increase winds across the

upsloping of the Central Highlands and along the eastern

border. As the front starts to exit after midnight, high res

models indicate that the pressure gradients on the backside of

the front will tighten again, causing a brief increase of winds

in the North Woods. Though short lived and weaker than previous

runs, decided to include this wind increase for impact purposes.

In addition, the HRRR has pointed to the possibility of a more

stable boundary layer due to possible snow pack surviving the

rain and warm temps. If the snow pack is a constant layer, there

is a possibility that winds will have a hard time mixing to the

surface with the latent heating. However, if the snow pack is

patchy or gone, then winds will remain at forecasted values.

Rain: As the cold front moves across the region tonight, bands

of high rain rates will move across the region. The main area of

concern will be the upsloping areas of the Central Highlands

and the downsloping in the North Woods. Though these higher rain

bands will move across certain areas, instability along the

front will cause some convection to develop, thus localized

heavier rain is possible. In addition to the rainfall, the

snowpack will be melting, causing extra runoff on frozen ground.

Though rivers are not as big of a concern, small streams,

creeks, and urban street flooding is a concern.

By Thursday, the low will exit over the Maritimes with wrap

around moisture bringing snow showers across the region

throughout the day. Cold air behind the front will gradually

drop temps throughout the day with the majority of the region

remaining in the upper 30s. Isolated snow showers are possible

across far northern Maine by evening.

&&

.SHORT TERM /THURSDAY NIGHT THROUGH SATURDAY/...

High pressure will begin to build into the area through the end

of the week and into the weekend. This will lead to drier

weather and clearing skies. Temperatures will be mild, with

highs in the 20s over most of the forecast area, and near 30

closer to the coast. Lows Thursday night may only fall into the

upper teens to lower 20s, but by Friday night could fall into

the lower teens across the forecast area. Light winds may linger

through the short term, limiting surface decoupling chances and

preventing temperatures from rapidly plummeting much further.

&&

.LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/...

High pressure will linger through this weekend. With mostly

clear skies and light winds, full surface decoupling may be

possible such that temperatures could fall into the lower single

digits above zero Saturday night, particularly across the north.

Otherwise, temperatures may remain slightly below average

through the rest of the weekend.

A low pressure system will approach from the west through early

next week. There remains great uncertainty for when this system

will enter the area, with the GFS and CMC bringing a small

shortwave over the area Monday night into Tuesday and bringing

the first round of light precipitation into the region.

Meanwhile, the Euro hangs on to high pressure over the area. The

main low may not move into the area until Tuesday night into

Wednesday. Ensemble plots agree on a slower progression of this

trough, though there remains the slight chance of showers ahead

of the main low.

&&

.AVIATION /03Z THURSDAY THROUGH MONDAY/...

NEAR TERM: IFR/LIFR for this evening and into tonight due to low

cigs, fog, and rain. Rain will continue to be heavy at times

for all terminals. Significant and unusually strong LLWS tonight

for all terminals. S winds 20-25 kts with gusts around 50 kts.

By Thursday, improving to VFR during the morning. SW winds

10-15 kts with gusts up to 20 kts.

SHORT TERM:

Thurs night - Fri night: VFR across all terminals. SW winds 5 to

10 kts, gusting 20 to 25 kts Thurs night, gradually diminishing

through Fri and Fri night.

Sat - Mon: VFR across all terminals. W winds around 5 kts

becoming light and variable Sat night, then turning S on Sun at

5 to 10 kts.

&&

.MARINE...

NEAR TERM: The Storm Warning is in effect through tonight with

seas 13-20 ft. Winds should decrease by Thursday morning to gale

force throughout the day with seas 11-16 ft decreasing to 7-12

ft by the afternoon.

SHORT TERM: Winds will quickly decrease back towards small craft

advisory levels through Thursday night, and may continue to

decrease below 25 kts by late Friday night. Seas with a long

period southerly swell will gradually decrease through the end

of the week, reaching 3 to 5 ft by Friday night.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...

ME...Flood Watch through Thursday morning for MEZ001>006-010-011-

     015>017-029>032.

     Dense Fog Advisory until 5 AM EST Thursday for MEZ001-002-004-

     005-010-031.

     Wind Advisory until 6 AM EST Thursday for MEZ001-003-004.

     High Wind Warning until 6 AM EST Thursday for MEZ002-005-006-

     010-011-015>017-029>032.

MARINE...Storm Warning until 7 AM EST Thursday for ANZ050>052.

&&

$$

Near Term...LaFlash/MStrauser

Short Term...AStrauser

Long Term...AStrauser

Aviation...LaFlash/MStrauser/AStrauser

Marine...LaFlash/AStrauser

URGENT - WEATHER MESSAGE

National Weather Service Caribou ME

631 PM EST Wed Dec 11 2024

MEZ001-004-121015-

/O.NEW.KCAR.FG.Y.0013.241212T0000Z-241212T1000Z/

/O.CON.KCAR.WI.Y.0011.241212T0000Z-241212T1100Z/

Northwest Aroostook-Northern Piscataquis-

Including the cities of Clayton Lake, Baxter St Park, Madawaska,

Fort Kent, Chamberlain Lake, Allagash, Churchill Dam,

Frenchville, and Mount Katahdin

631 PM EST Wed Dec 11 2024

...DENSE FOG ADVISORY IN EFFECT UNTIL 5 AM EST THURSDAY...

...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM EST THURSDAY...

* WHAT...For the Dense Fog Advisory, visibility of a quarter-mile or

  less in dense fog. For the Wind Advisory, south winds 15 to 25 mph

  with gusts up to 45 mph expected.

* WHERE...Northwest Aroostook and Northern Piscataquis Counties.

* WHEN...For the Dense Fog Advisory, until 5 AM EST Thursday. For

  the Wind Advisory, until 6 AM EST Thursday.

* IMPACTS...Gusty winds will blow around unsecured objects. Tree

  limbs could be blown down and a few power outages may result. Low

  visibility could make driving conditions hazardous.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Winds this strong can make driving difficult, especially for high

profile vehicles. Use extra caution.

If driving, slow down, use your headlights, and leave plenty of

distance ahead of you.

&&

$$

URGENT - WEATHER MESSAGE

National Weather Service Caribou ME

631 PM EST Wed Dec 11 2024

MEZ001-004-121015-

/O.NEW.KCAR.FG.Y.0013.241212T0000Z-241212T1000Z/

/O.CON.KCAR.WI.Y.0011.241212T0000Z-241212T1100Z/

Northwest Aroostook-Northern Piscataquis-

Including the cities of Clayton Lake, Baxter St Park, Madawaska,

Fort Kent, Chamberlain Lake, Allagash, Churchill Dam,

Frenchville, and Mount Katahdin

631 PM EST Wed Dec 11 2024

...DENSE FOG ADVISORY IN EFFECT UNTIL 5 AM EST THURSDAY...

...WIND ADVISORY REMAINS IN EFFECT UNTIL 6 AM EST THURSDAY...

* WHAT...For the Dense Fog Advisory, visibility of a quarter-mile or

  less in dense fog. For the Wind Advisory, south winds 15 to 25 mph

  with gusts up to 45 mph expected.

* WHERE...Northwest Aroostook and Northern Piscataquis Counties.

* WHEN...For the Dense Fog Advisory, until 5 AM EST Thursday. For

  the Wind Advisory, until 6 AM EST Thursday.

* IMPACTS...Gusty winds will blow around unsecured objects. Tree

  limbs could be blown down and a few power outages may result. Low

  visibility could make driving conditions hazardous.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

Winds this strong can make driving difficult, especially for high

profile vehicles. Use extra caution.

If driving, slow down, use your headlights, and leave plenty of

distance ahead of you.

&&

$$

9:15 PM AST Wednesday 11 December 2024

Wind Warning in effect for:

Yarmouth County

Strong winds that may cause damage are expected or occurring.

Maximum wind gusts: southerly 90 km/h.

Locations: Digby, Yarmouth, and Shelburne Counties.

Time span: near midnight tonight to Thursday morning.

High winds may result in power outages and fallen tree branches.

Be prepared to adjust your driving with changing road conditions due to high winds.

Wind warnings are issued when there is a significant risk of damaging winds.

Please continue to monitor alerts and forecasts issued by Environment Canada. To report severe weather, send an email to NSstorm@ec.gc.ca or tweet reports using #NSStorm.