Destructive Subtropical System

000

FXUS61 KCAR 160317

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

1017 PM EST Fri Dec 15 2023

.SYNOPSIS...

A cold front will cross the region tonight followed by high

pressure over the weekend. Strong low pressure will track up the

East Coast on Monday then pass to our west and continue north

into Canada Monday night into Tuesday. High pressure will return

on Wednesday.

&&

.NEAR TERM /THROUGH SATURDAY/...

1017 PM Update: A band of cirrus continues to stretch across

the middle of the forecast area tonight, with lower stratocu

seen across the western half of the CWA. Temperatures have

remained mild underneath the high clouds that exist so far, and

a more substantial band of lower stratus clouds can be seen on

the current Nighttime Microphysics RGB satellite product

approaching the St. John Valley from the north. This band of

clouds will also limit how quickly temperatures fall once it

sinks into the area, and may even lead to a few isolated snow

showers through late tonight.

Previous Discussion:

A very weak cold front will move through the region tonight.

Unseasonably warm temps will remain fairly stagnant through this

evening and early tonight, especially will the increasing cloud

cover to the south. The 925-850mb model temps indicate the cold

air behind the front will start to move through after midnight

tonight, thus beginning to slowly decrease temps in the north

towards Saturday morning. The approaching high pressure system

over Quebec will continue to tighten pressure gradients, making

WNW winds breezy through the night. By Saturday, high pressure

will begin to settle into the region. RH models show dry air

with this system, which will push out the remaining clouds,

making for progressively sunny skies. Temps will be cooler into

the upper 20s in the north and mid 30s in the south. As the

center of the high moves over the region in the afternoon, winds

will decrease to calm and variable.

&&

.SHORT TERM /SATURDAY NIGHT THROUGH MONDAY/...

     High impact wind and rain storm Monday...

A 1038mb sfc high will rapidly exit east of the area and

strengthen Saturday night. Low temps will occur in the evening

with a trend towards rising temperatures and increasing clouds

later in the night.

For Sunday, thickening clouds and a strengthening south flow

will produce steadily rising temps towards the 40s by evening.

With an influx of low level moisture, expect some drizzle to

break out in the morning...especially in upslope locations with

respect to the southerly flow. Although temps will be rising

fairly quickly above freezing with cold air damming worries,

some freezing drizzle is possible in the morning into early

afternoon. This would be most likely north of Dover-Foxcroft and

Houlton.

Rain chances increase steadily through Sunday afternoon and

evening as deeper moisture arrives over the area. Warm air

advection continues Sunday night with steadily rising

temperatures and rainfall overspreading the entire area.

Deepening low pressure will advance northward from Florida with

an anomalous plume of deep subtropical moisture from the

Caribbean. By early morning, the low is forecast to be along

the Delmarva coast. As the low deepens, the pressure gradient

between the low and the blocking high in the Atlantic will

tighten dramatically. This will mean rapidly increasing south

winds later Sunday night.

Another powerful low level jet emerges on the cyclonic side of

the approaching low. The magnitude of the 850mb is likely to be

in excess of 100 kt again while the 925mb speeds may reach 100

kt on the coast. Unlike the storm from last Monday, the surface

low will be tracking much further west. This presents much

higher odds for damaging wind gusts for the entire forecast

area. As usual, the coast stands most likely to see the highest

wind speeds. Have taken a conservative approach to start this

event by undercutting NBM winds for now. Even then, our current

forecast suggests a High Wind Warning on the coast and Wind

Advisories northward to Aroostook County. Again, this is

conservative. The peak winds are currently expected Monday

afternoon into the early evening.

While winds may be the most impactful part of the this storm

across the entire area, the deep tropical moisture will deliver

rainfall amounts in excess of 2 inches in the Central Highlands.

Temperatures well into the 50s as well as dew points in the 50s

will melt all snow in the forecast area. While SWE is rather

low, it will still add to the runoff in locations such as the

North Woods.

There is also a coastal flooding aspect to this storm addressed

in the coastal flooding section below.

&&

.LONG TERM /MONDAY NIGHT THROUGH FRIDAY/...

The long term is relatively benign after the Monday storm. Mild

temperatures continue Monday night and winds will slowly

diminish by later in the evening. Colder air slowly arrives

Tuesday with temperatures dropping off in the afternoon and

evening. The challenge in the forecast will be whether colder

air arrives in time to coincide with a swath of moisture moving

north with the departing upper low. If the timing works out, a

few inches of snow could result as advertised by some of the

models. However, confidence is not high. Will go with a chance

of snow spreading across northern zones later Tuesday afternoon

and evening.

Seasonably mild conditions continue through Wednesday. A clipper

system will bring a cold front across the area Wednesday night

into Thursday. Will not introduce PoPs at this time, but these

systems are always a threat to deliver an inch or two of fluffy

snow. Will go with more seasonably cold temps for Thursday into

Friday.

&&

.AVIATION /03Z SATURDAY THROUGH WEDNESDAY/...

NEAR TERM: VFR conditions across all terminals tonight. W to WNW

winds 5-15 kts with LLWS for all terminals, except BHB, for

most of tonight. VFR conditions continue into the day on

Saturday, aside from the potential for brief MVFR cigs at FVE

should a few lower ceiling snow showers cross the terminal early

Saturday morning.

SHORT TERM:

Saturday night...VFR with light winds.

Sunday...Becoming IFR due to cigs during the day. Chance of

freezing drizzle...mostly north of GNR and HUL through mid

afternoon.  Possible LLWS by afternoon.

Sunday night...IFR tempo LIFR due to cigs, fog and drizzle. LLWS

expected.  South winds 10 to 20 kt.

Monday...IFR tempo LIFR due to cigs and heavy rain. Dangerous

LLWS possible. South winds 20 to 40 kt.

Monday night...IFR due to cigs, LLWS ending in evening.

South winds 15 to 30 kt.

Tuesday...Mostly MVFR tempo IFR due to cigs and showers.

Possible snow late afternoon north of HUL. Southwest winds 5 to

15 kt.

Wednesday...VFR with west winds 5 to 10 kt.

&&

.MARINE...

NEAR TERM: Winds and seas diminish slightly tonight, then wind

gusts will increase Saturday morning back towards 25 kts for the

rest of the day. Seas 1-3 ft.

SHORT TERM: Monday will be the big event with possible storm

conditions. Winds and seas will ramp up steadily Sunday and

Sunday night, peaking Monday afternoon and evening. Seas will

max out up to 25 ft. Winds will drop off fairly quickly Monday

night, but seas will remain elevated to necessitate advisories

well into next week.

&&

.HYDROLOGY...

Heavy rains later Sunday night through Monday raises the threat

of another round of urban and small stream flooding issues. Over

2 inches of rainfall may fall during the period in upslope portions

of Piscataquis and Penobscot counties. While little snowmelt

will contribute to this round, partially frozen ground will

still cause rapid runoff, especially in areas with more complex

terrain. At this point, river ice does not look like a threat to

produce any jams.

&&

.TIDES/COASTAL FLOODING...

The high tide near 245pm on Monday bears watching. While not a

particularly high astronomical tide, strong storm surge and seas

over 20 ft may cause minor coastal flooding and wave runup

issues. With the strong southerly push, will also have to look

for surge up the Penobscot River to Bangor.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...

ME...None.

MARINE...None.

&&

$$

Near Term...AStrauser/LaFlash

Short Term...MCW

Long Term...MCW

Aviation...AStrauser/LaFlash/MCW

Marine...AStrauser/LaFlash/MCW

Hydrology...MCW

Tides/Coastal Flooding...MCW

9:53 PM AST Friday 15 December 2023

Another round of heavy rain and strong winds expected to start next week.

Possible wind gusts: southeasterly near 80 km/h.

Possible rainfall amount: 40 to 60 mm by Tuesday.

Timing: beginning Sunday overnight and intensifying Monday.

Locations: southern New Brunswick.

Remarks: At this time there remains considerable uncertainty in regards to which specific counties will see the heaviest rain and strongest winds. It is likely that this will be an impactful weather event for areas that have already seen a lot of precipitation recently. New Brunswick is now on winter rainfall criteria of 25mm/24hrs. 

Continue to check for updated alerts and forecasts this weekend as this storm evolves.

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

9:44 PM AST Friday 15 December 2023

Strong winds and heavy rainfall are expected early next week.

Strongest winds gusts: could exceed 100 km/h.

Possible rainfall amounts: 30 to 50 mm by Tuesday.

Timing: late Sunday night and continuing Monday.

Locations: P.E.I.

Remarks: A large low pressure system is forecast to develop and track over the maritimes on Monday. This system will bring very strong winds and heavy rain to the Island. 

Continue to monitor alerts and updated forecasts this weekend to learn specifics for your county as the event draws nearer.

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

9:38 PM AST Friday 15 December 2023

Another round of heavy rain and strong winds expected to start next week.

Possible wind gusts: southeasterly near 100 km/h, except 120 km/h or higher from Margaree Harbour to Bay St. Lawrence.

Possible rainfall amount: 50 to 70 mm by Tuesday.

Timing: beginning overnight Sunday and intensifying Monday.

Locations: Nova Scotia.

Remarks: At this time there remains considerable uncertainty in regards to which counties will see the heaviest rain and strongest winds. It is likely this will be an impactful weather event for areas that have recently seen a lot of precipitation and damaging winds. 

Large waves and pounding surf will produce higher than normal water levels along the Atlantic coast, especially near high tide around midnight Monday night.

Continue to check for updated alerts and forecasts this weekend as this storm evolves.

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.

Hazardous Weather Outlook

National Weather Service Caribou ME

305 PM EST Fri Dec 15 2023

MEZ001>006-010-011-015>017-029>032-162015-

Northwest Aroostook-Northeast Aroostook-Northern Somerset-

Northern Piscataquis-Northern Penobscot-Southeast Aroostook-

Central Piscataquis-Central Penobscot-Southern Penobscot-

Interior Hancock-Central Washington-Coastal Hancock-

Coastal Washington-Southern Piscataquis-Northern Washington-

305 PM EST Fri Dec 15 2023

This Hazardous Weather Outlook is for Central Highlands Maine,

Coastal DownEast Maine, Far Eastern Maine, Far Northern Maine,

Interior DownEast Maine, North Woods Maine and Penobscot Valley

Maine.

.DAY ONE...This afternoon and tonight.

Hazardous weather is not expected at this time.

.DAYS TWO THROUGH SEVEN...Saturday through Thursday.

Intense low pressure tracking through western New England into Quebec has

the potential to bring very strong southerly winds in excess of 50

mph across the region on Monday. The Downeast coast may experience

even stronger wind gusts.  Moderate to heavy rainfall is also

expected Sunday night into Monday night. Urban and small stream

flooding is possible.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather

conditions according to Standard Operating Procedures.

$$