Early December Wind & Rain Storm Update Two

000

FXUS61 KCAR 110024

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

724 PM EST Sun Dec 10 2023

.SYNOPSIS...

Intensifying low pressure tracks across Maine Monday and will

draw a cold front across the region Monday evening. High pressure

builds Monday night into Tuesday. A cold front moves through

Wednesday. High pressure builds south of the waters Thursday.

&&

.NEAR TERM /THROUGH MONDAY NIGHT/...

7pm update...The storm track for Monday continues to ease

southward and eastward. This means less wind worries for

locations such as Bangor and interior Downeast. The worst of the

winds appears most likely in coastal Washington County. As the

threat of high winds, the other side of the pendulum swings

towards more snow across the North Woods. Amounts of more than a

foot of heavy wet snow are possible in the warning area. The

strong winds following the end of precip remain a worry with

regard to trees loaded with heavy, wet snow. Areas west of Rt 11

in Aroostook County will have the most snow. Locations such as

Caribou and Presque Isle may pick up a quick 2 inches on the

backside...which will create travel headaches as temperatures

plummet.

While temperatures will not be as warm as previously thought on

Monday, heavy rainfall remains a big concern with rapid runoff

over the partially frozen ground. With the southward shift in

the low track, the max corridor appears to easing slightly south

of the I-95 corridor. However, this corridor is still

susceptible to 3 to 4 inches of rain and possibly more. This

provides a good likelihood of some urban and small stream

flooding issues to include the Bangor and Ellsworth areas. Most

of the precip should be over by early afternoon.

     Powerful Storm Impacts Maine Tonight into Monday Evening...

Setup...Strong storm system we`ve been advertising still on

track to begin impacting Maine tonight. Overall, setup is quite

dynamic, with a slow-moving frontal boundary setting up over

the forecast area oriented SW/NE tonight. Then with the support

of a strong 500mb shortwave and upper level jet, a surface low

rapidly intensifies as it moves NE along the front and over the

area Monday. Lots of moisture to work with from the Gulf of

Mexico, with very high precipitable water values along/east of

the front. The FGEN forcing will increase along that boundary

increasing rainfall rates along with a southerly wind component

aiding in upslope enhancement.

Models...Uncertainty continues to exist this evening with where

the boundary sets up across our FA. It will extend SW to NE

across the area. 12z GFS, Canadian and NAM trended a little more

southeast with the boundary extending from Midcoast Maine to

just South of Hodgdon to Danforth area. ECMWF continues to be a

little more NW with the boundary versus the overall trend. AI

models show a continued slightly more easterly trend with the

boundary. Opted to go with a trend being your friend as a

forecaster and slightly shifted the boundary. This will play

into adjustments to the precip type and winds seen below.

Rain/Flooding...Combination of melting snowpack, partially

frozen grounds and very heady rainfall poses a threat for

flooding across much of the CWA. Strong frontal forcing along

the boundary across our CWA will strengthen tonight and be the

focal point for heavy rainfall rates. PWATs are climbing to

0.75-1.00 inch above climatological normals. Heavy rain will be

possible in nearly the entire FA tonight into Monday AM. We will

see precip type changes in the North Woods which will be

mentioned below. Given the less than likely chance of dew points

being >40F in Northern Piscataquis opted to remove this zone

from the Flood Watch otherwise the Flood Watch remains in place

for Eastern Aroostook, Central Highlands to Downeast coast from

late tonight through Tuesday AM. Additional hydrological

concerns are addressed in the hydro section below.

Wind...Tonight ahead of low pressure tracking NE towards Maine a

925mb low-level jet will increase to 80-95kt and push into the

Maine coast by morning. This will extend from the Midcoast into

Downeast Maine and will likely penetrate inland across interior

Downeast. The boundary will play a crucial role since if you are

on the cold air side of the front winds will be very light due

to winds remaining aloft of the inversion. Portions of the

Central Highlands southeast of I-95 towards the Downeast coast

will have a good shot at mixing a large portion of the LLJ down

to the surface. Forecast soundings show the LLJ below the steep

inversion around 900mb with 50-70kt winds below the inversion.

This will result in winds gusting 40-50mph SE of I-95 in the

southern portions of Aroostook County into far eastern portions

of Penobscot against the border with Hancock county. Hancock and

Washington county have the best shot at gusting 55-65mph north

of Route 1 with areas along the shore south of Route 1 having

the best chance at gusting up to 70mph. Right at the immediate

coastline and on top of Cadillac cannot rule out slightly

higher gusts. Highest confidence in 70mph gusts will be in

coastal Washington County with moderate-high confidence for

coastal Hancock county. Inland the gusts confidence is moderate

due to uncertainty with the boundary. For now...opted to keep

the Wind Advisory and High Wind Warning in place as is.

Snow...This has been another tricky part of this forecast with

the continued trend east in the models setting us up for

potential of dynamical cooling to increase snow chances. At this

time opted to take the low on that SSW to NNE path through Maine

from Midcoast to approx Danforth area. Historical analysis for

events in Maine suggest more snowfall across the North Woods to

Route 11 area in Northern Penobscot and Aroostook County.

Additionally, this favors some more snow into Eastern Aroostook

to the New Brunswick border. Forecast soundings indicate strong

dynamical cooling on the NW side as FGEN forcing moves in aloft.

Tonight, along the Quebec border expect rainfall to change to

snow after midnight into Monday AM pushing eastward. Cannot rule

out some brief sleet and/or freezing rain as cold air works

under the warm air aloft till the cooling changes ptype to snow.

Snowfall rates possibly will reach 1-2 inches per hour as

temperatures fall below freezing across the North Woods into

western St. John Valley from Fort Kent westward into Monday.

Snow will be wet and heavy as the column is isothermal. Winds

will be light intially but as the low tracks NE through Maine

the pressure gradient induced W-NW winds will gust up 30-40mph

in spots. This poses the risk of power outages from Fort Kent

westward along Route 161 into Allagash. Given the increased snow

going with totals of 6-9 inches with isolated higher amounts

opted to upgrade N Somerset and NW Aroostook to Winter Storm

Warning for heavy mixed precipitation. Issued a Winter Weather

Advisory for mixed precipitation in N. Piscataquis county.

Lastly, by midday into late afternoon cannot rule out snow

reaching Route 11 to Mapleton, Washburn, Presque Isle and

Caribou areas and these locations may pick up a few inches of

snow that may require a winter headline but opted to wait for

now with the flood risk first.

Additional threats...Coastal flooding is expected to be mainly a

wave runup issue around the 9AM high tide on Monday. See the

coastal flood section below. Lastly, temperatures late Monday

into Monday evening as the storm departs NE expect rapid

temperature fall. This may result in refreeze of untreated

surfaces with potentially a flash freeze if the winds don`t dry

surfaces up first.

&&

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

Fair and with avg to slgtly below avg hi temps can be xpctd Tue

behind Mon`s storm with dmnshg WNW winds. Warm advcn begins

quickly by Tue Eve ahead of an Alberta clipper s/wv with anti-

diurnal ovrngt temp trends. Isold to sct sn shwr PoPs are xpctd

across Nrn areas ahead to just behind the cold frontal passage

passage late Tue Ngt into erly Wed Morn with little in the way

of accumulation. Brisk NW winds return for the FA behind the

cold front for Wed Aftn and Wed Ngt with little in the way of

radiational cooling Wed Ngt even for protected NW vlys. Outside

of isold narrow St Lawrence sn shwr streamers across the N, dry

conditions are xpctd with below avg temps with semi- arctic air

behind the front.

&&

.LONG TERM /THURSDAY THROUGH SUNDAY/...

Recent CPC 6-10 day outlooks confirmed by Tdys latest 12z long

range models have been consistent in advertising Nrn anomalous

component of flow alf ovr Nrn New Eng with abv avg 500mb hts for

the long range. This implies msly dry conditions for this ptn

of the fcst. After chilly, brisk conditions on Thu, temps look

to modify by Fri before another clipper s/wv brings somewhat

colder conditions on Sat, with the cold frontal passage late Fri

Ngt looking dry at this tm. The next chc of any rn/sn shwrs for

the FA with the next Alberta clipper s/wv with be Sun Ngt into

Mon with little if any in of measurable precip. Temps look to

be be abv avg from Fri thru Sun attm.

&&

.AVIATION /00Z MONDAY THROUGH FRIDAY/...

NEAR TERM: MVFR at BHB, IFR/LIFR elsewhere. LLWS at northern

terms early. IFR/LIFR tonight for all sites. LLWS likely at

southern terms tonight into tomorrow. IFR/LIFR due to vsby/cigs

in rain, heavy at times. RA becomes SN from 16-20z at FVE, CAR,

PQI tomorrow with SN possible at HUL by 22z. RA before 18z at

southern terms becomes -SHRA. LLWS comes to an end by late day.

Surface winds light and variable at northern terms through 06z

becoming N 5-15kt. Winds at northern terms shift NW after 18z

tomorrow becoming 10-20kt with gusts up to 30kt. Southern terms

S winds 10-20kt tonight with gusts up to 35kt becoming S 20-35kt

tomorrow with gusts up to 50kt at BGR and 60kt at BHB. Winds

shift W-NW after 20z tomorrow and decrease to 15-25kt.

SHORT TO LONG TERM: Tue - Thu...Msly VFR clgs with intermittent

MVFR clgs with isold sn shwrs Nrn TAF sites spcly Wed until Thu

Morn. Lgt to mdt SW winds becmg NW Wed Aftn and contg into Thu.

Thu Ngt - Fri...Low VFR clgs Nrn TAF sites to unlmtd VFR Downeast

sites. Lgt to mdt W to SW winds.

&&

.MARINE...

NEAR TERM: Storm Warning remains in effect 1AM to 7PM Monday for

dangerous wind gusts across the coastal waters. Southerly gales

rapidly develop this evening becoming storms overnight. Winds

gusting up to 60kt with a few gusts up to 65kt possible

especially over eastern waters. Winds will drop to gusts up to

40kt Monday afternoon as winds shift W. Southerly swells rapidly

increase tonight 7-15ft by daybreak with a period of 7-8

seconds. Swells become 18-22ft over the coastal waters out 25nm.

Intra-coastal waters will see 10-16ft. Tomorrow`s wave period

will be 11-12 seconds. Waves will begin to subside after winds

shift W-NW.

SHORT TO LONG TERM: Winds and seas will msly be at or abv SCA

thresholds thru Fri, with strong SCAs possible Tue Ngt into Wed Morn

with SW winds and again Wed Ngt into Thu Morn with NW winds with

possible gale force wind gusts for this second pd. Winds and seas

will drop below SCA lvls by the weekend. Kept with blended wv model

guidance for this update. Long pd swells of 10-12 sec pds will

msly compose wvs with a secondary 5 to 8 sec shorter fetch

group.

&&

.HYDROLOGY...

Melting snowpack and heavy rainfall to pose a hydrologic threat

across a large portion of Eastern and Northern Maine. Ice is

present on some of the rivers but will not be that big of a

concern. There is frazil and pancake ice that has frozen in

place on the St. John and Aroostook River basins along with

other smaller creeks and streams across much of the CWA. We saw

significant compaction and melting of the snowpack across Maine

today. Frost depth here at NWS Caribou is 3 inches and is

generally 1 to 4 inches across the CWA. In this snow remaining

we generally see 0.5 to 1.0 inches of SWE that is likely to

melt tonight with this event.

The combination of heaviest rainfall, SWE melting and the

partially frozen grounds corresponds to a flood threat on small

creeks and streams. The Piscataquis River which is prone to

rapid rises and has a complex terrain in the basin is likely to

experience minor flooding. The Northeast River Forecast Center

is predicting the Piscataquis at Dover-Foxcroft to rise to

Minor Flood Stage on Monday. In addition, large rivers will

experience rises Monday into Tuesday AM before cresting which

could send some locations into action stage. Not expecting

flooding at this time, however highly isolated issues may occur

as rivers approach bankfull. Lastly, urban and poor drainage

flooding is possible with excessive rainfall and potentially

clogged drains.

&&

.TIDES/COASTAL FLOODING...

The high tide near 9AM Monday morning represents the biggest

risk for any coastal flooding and wave runup issues. There are

two mitigating factors. First, it is not a particularly high

astronomical tide. Second, peak surge is about 4 to 5 hours

after the high tide based on current projections. In this

scenario, wave runup becomes the primary concern. Seas

approaching 10-16 ft could deposit rocks on roads exposed to

the open ocean. That includes Mount Desert Island locations such

as Seawall Road and coastal roads on the Schoodic Peninsula. Do

not anticipate needing any coastal flood warnings, as this looks

like either a coastal flood statement or advisory scenario.

&&

.CAR WATCHES/WARNINGS/ADVISORIES...

ME...Winter Storm Warning from 1 AM to 7 PM EST Monday for MEZ001-

     003.

     Flood Watch from 1 AM EST Monday through Tuesday morning for

     MEZ002-005-006-010-011-015>017-029>032.

     Winter Weather Advisory from 3 AM to 7 PM EST Monday for

     MEZ004.

     Wind Advisory from 1 AM to 7 PM EST Monday for MEZ006-011-015.

     High Wind Warning from 1 AM to 7 PM EST Monday for MEZ016-017-

     029-030-032.

MARINE...Storm Warning from 1 AM to 7 PM EST Monday for ANZ050>052.

&&

$$

Near Term...MCW/Sinko

Short Term...VJN

Long Term...VJN

Aviation...MCW/Sinko/VJN

Marine...MCW/Sinko/VJN

Hydrology...

Tides/Coastal Flooding...

URGENT - WINTER WEATHER MESSAGE

National Weather Service Caribou ME

742 PM EST Sun Dec 10 2023

MEZ001-110845-

/O.CON.KCAR.WS.W.0016.231211T0600Z-231212T0000Z/

Northwest Aroostook-

Including the cities of Frenchville, Madawaska, Allagash, Clayton

Lake, and Fort Kent

742 PM EST Sun Dec 10 2023

...WINTER STORM WARNING REMAINS IN EFFECT FROM 1 AM TO 7 PM EST

MONDAY...

* WHAT...Heavy snow expected. Total snow accumulations between 8 and

  12 inches.  The heavier amounts will be west of Route 11.  Winds

  gusting as high as 35 mph.

* WHERE...Northwest Aroostook County.

* WHEN...From 1 AM to 7 PM EST Monday.

* IMPACTS...Travel could be very difficult. Snowfall rates of 1 to 2

  inches an hour will make travel very hazardous. The hazardous

  conditions could impact the Monday morning and evening commutes.

  Gusty winds could bring down tree branches.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Storm Warning for snow means severe winter weather

conditions will make travel extremely dangerous. If you must travel,

keep an extra flashlight, food, and water in your vehicle in case of

an emergency.

The latest road conditions for Maine can be obtained by going to

newengland511.org.

&&

$$

URGENT - WINTER WEATHER MESSAGE

National Weather Service Caribou ME

742 PM EST Sun Dec 10 2023

MEZ004-110845-

/O.CON.KCAR.WW.Y.0026.231211T0800Z-231212T0000Z/

Northern Piscataquis-

Including the cities of Chamberlain Lake, Churchill Dam, Mount

Katahdin, and Baxter St Park

742 PM EST Sun Dec 10 2023

...WINTER WEATHER ADVISORY REMAINS IN EFFECT FROM 3 AM TO 7 PM EST

MONDAY...

* WHAT...Snow expected. Total snow accumulations between 3 and 12

  inches. The higher amounts will be in the far northwestern part of

  the advisory area.  Winds gusting as high as 40 mph.

* WHERE...Northern Piscataquis County.

* WHEN...From 3 AM to 7 PM EST Monday.

* IMPACTS...Travel could be very difficult. The hazardous conditions

  could impact the Monday morning and evening commutes. Strong winds

  could cause extensive damage to trees and power lines.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Winter Weather Advisory for snow means periods of snow will cause

primarily travel difficulties. Expect snow covered roads and limited

visibilities, and use caution while driving.

The latest road conditions for Maine can be obtained by going to

newengland511.org.

&&

$$

URGENT - WEATHER MESSAGE

National Weather Service Caribou ME

301 PM EST Sun Dec 10 2023

MEZ016-017-029-030-032-111000-

/O.CON.KCAR.HW.W.0004.231211T0600Z-231212T0000Z/

Interior Hancock-Central Washington-Coastal Hancock-

Coastal Washington-Northern Washington-

Including the cities of Amherst, Aurora, Dedham, Eastbrook,

Great Pond, Calais, Grand Lake Stream, Wesley, Princeton,

Ellsworth, Bar Harbor, Bucksport, Orland, Castine, Eastport,

Perry, Machias, Cherryfield, Danforth, Vanceboro, and Topsfield

301 PM EST Sun Dec 10 2023

...HIGH WIND WARNING REMAINS IN EFFECT FROM 1 AM TO 7 PM EST

MONDAY...

* WHAT...South winds 30 to 40 mph with gusts up to 60 mph

  expected...except gusts up to 70 mph along the coast.

* WHERE...Interior Hancock, Central Washington, Coastal Hancock,

  Coastal Washington and Northern Washington Counties.

* WHEN...From 1 AM to 7 PM EST Monday.

* IMPACTS...Damaging winds will blow down trees and powerlines.

  Numerous to widespread power outages are likely. Travel will

  be difficult, especially for high profile vehicles.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

People should avoid being outside in forested areas and around

trees and branches. Use caution if you must drive.

&&

$$

3:51 PM AST Sunday 10 December 2023

Heavy rain is expected. The frozen ground has a reduced ability to absorb this rainfall.

Total rainfall: 40 to 70 mm by Monday morning. Potentially higher in heaviest rain.

Location: most of New Brunswick

Time span: beginning this evening and continuing until Monday evening.

Remarks: Strong winds and mild temperatures will accompany the rain, leading to significant snowmelt and run-off. The rain is likely to change to snow over parts of northwest New Brunswick before ending Monday night.

Heavy downpours can cause flash floods and water pooling on roads. Localized flooding in low-lying areas is possible.

Rainfall warnings are issued when significant rainfall is expected.

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.

3:50 PM AST Sunday 10 December 2023

Strong winds that may cause damage are expected or occurring.

Maximum gusts: southerly 80 to 100 km/h.

Locations: southern New Brunswick.

Time span: Monday afternoon until Monday evening.

Damage to buildings, such as to roof shingles and windows, may occur. Utility outages may occur.

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 NBstorm@ec.gc.ca or tweet reports using #NBStorm.

3:51 PM AST Sunday 10 December 2023

Heavy rain is expected. The frozen ground has a reduced ability to absorb this rainfall.

Total rainfall: 40 to 70 mm by Monday morning. Potentially higher in heaviest rain.

Location: most of New Brunswick

Time span: beginning this evening and continuing until Monday evening.

Remarks: Strong winds and mild temperatures will accompany the rain, leading to significant snowmelt and run-off. The rain is likely to change to snow over parts of northwest New Brunswick before ending Monday night.

Heavy downpours can cause flash floods and water pooling on roads. Localized flooding in low-lying areas is possible.

Rainfall warnings are issued when significant rainfall is expected.

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.

3:50 PM AST Sunday 10 December 2023

Strong winds that may cause damage are expected or occurring.

Maximum gusts: southerly 80 to 100 km/h.

Time span: Monday afternoon until Monday evening.

Damage to buildings, such as to roof shingles and windows, may occur. Utility outages may occur.

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 PEstorm@ec.gc.ca or tweet reports using #PEStorm.

3:50 PM AST Sunday 10 December 2023

Strong winds that may cause damage are expected or occurring.

Maximum gusts: southerly 80 to 100 km/h.

Locations: Nova Scotia.

Time span: Monday afternoon until Monday night.

Damage to buildings, such as to roof shingles and windows, may occur. Utility outages may occur.

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.