The Polar Vortex Arrives

000

FXUS61 KCAR 030335

AFDCAR

Area Forecast Discussion

National Weather Service Caribou ME

1035 PM EST Thu Feb 2 2023

.SYNOPSIS...

A powerful arctic cold front will cross the area Friday

morning. Frigid arctic high pressure will build in from the west

Friday into Saturday. A warm front will lift across the area

Sunday. Weak low pressure will track north of the area Monday.

&&

.NEAR TERM /THROUGH FRIDAY/...

Dangerously Low Wind Chills and Blowing Snow Friday through

Saturday…

1035 pm update...

Arctic front is moving very quickly twd the FA with snow squalls

moving btwn 50-55 mph and should enter into the North Woods

right around midnight tonight. The snow squalls will be the

beginning of the extreme cold, dangerous wind chills and

blizzard conditions expected to last through the day Saturday.

Whiteout conditions are expected across nrn and central areas

with fropa as winds increase to between 25-35 mph tonight from

the northwest. Ground blizzard conditions still look to be on

track through the day tomorrow and into Saturday with winds

being maximized Sat morning. Wind chills will be dropping

throughout the day on Friday and likely reaching their lowest

values on Sat morning, somewhere on the order of 50 to 60 below

and worse on the higher terrain.

Prev discussion blo...

The arctic front arrives later tonight with plunging

temperatures, blowing snow and dangerous wind chills. The front

crosses after midnight and is expected to be exiting the state

by 4am. Brief snow squalls will accompany the front and may

cause whiteouts, mainly in the northern half of the CWA.

Temperatures plummet with the frontal passage and continue to

fall relentlessly into Friday night. With steep low level lapse

rates, winds kick up immediately with frontal passage with gusts

reaching the 35 to 45 mph range. Blowing snow will start with

the frontal passage and continue all day and into Friday night.

The worst will be in Aroostook County where the Blizzard Warning

was issued due to the blowing snow/ground blizzard threat in

open terrain. Wind chills drop steadily all day into the

evening, reaching below minus 50F by late afternoon in the Saint

John Valley and dropping towards minus 45F at Bangor by late

evening.

The air mass descending from Hudson Bay towards Maine is the

coldest in the Northern Hemisphere as measured by 925mb temps.

925mb temps are expected to drop towards -35C in northern

Aroostook County by later Friday. 850mb temperatures are still

expected to drop towards -40C and challenge the all-time record

at Caribou when our 04/00Z radiosonde is launched.

It is a very dry air mass with precipitable water at the very

lowest end of climate around two-hundredths of an inch. This is

fortunate in limiting snow shower activity. The only source of

moisture will be the St Lawrence River. Maintained mention of

isolated snow showers in portions of Aroostook County much of

the day based on the premise of the extremely cold air advecting

southward picking up some of that moisture and poor model

performance in past situations.

Interestingly, using CIPS analogs, a top analog is the Jan 14,

1988 event when Caribou last experienced a wind chill of less

than minus 50F. The lowest recorded wind chill at Caribou was

minus 58.6F in 1951.

The Blizzard Warning was issued in response to the blowing snow

and whiteout threat in the warned area. Snow accumulations will

be an inch or less. The blowing snow threat will be in open

terrain where whiteouts are most likely to affect motorists.

Discussions with state and county authorities involved in

public safety this week, and after similar events in past years,

have favored this stronger alert/messaging.

As we said in our last discussion, travel over open areas

exposed to northwest winds will be dangerous at best and

impossible at worst due to ground blizzard conditions and

significant drifting making some roads impassable. Those who

must travel across open areas Friday through Saturday morning

should be prepared if they become stranded with a full tank of

gas and winter survival supplies. It is also critical people do

not leave their vehicles in whiteout conditions and very cold

wind chills.

&&

.SHORT TERM /FRIDAY NIGHT THROUGH SATURDAY/...

Friday night and

Saturday will be the most dangerous time frame for windchills as

the overnight lows hit their minimum. As the Arctic air mass

moves in, it will be accompanied by a LLJ nearing 50 to 60 knots

at 850 hPa. The coldness of the air aloft should help these

winds mix down, and gusty winds will continue behind the Arctic

front through at least midday on Saturday. Although ambient

temperatures will be cold, they will not reach record breaking

lows. The amplifying factor will be the wind, which will reach

peak gusts of 35 to 40 mph early Saturday morning, bringing

windchills dangerous lows of -50 to -55F across the entire

forecast area. Winds will finally begin to subside in the

afternoon as the ridge moves overhead and the LLJ moves off to

the east. The cold air will remain in place, so although wind

chills will significantly warm, ambient temperatures will remain

below zero for most of the area and some places may see record

low max Ts on Saturday, followed by low temps from 0 to -20F

again Saturday night.

This will be a short-lived deep freeze, however, as the ridge

moves eastward on Sunday and the air mass aloft begins to warm.

By Sunday morning, temps at 850 hPa will have warmed to -10 to

-15C, and surface temperatures on Sunday will be much more

 seasonable. A weak surface low will develop along the coast

 Saturday night and move northward into the Bay of Fundy,

 bringing a quick shot of snow for Sunday afternoon. This will

 mostly fall over the Downeast region, but snowshowers are

 possible through northern Maine as well. Very little QPF is

 expected, and even with high snow ratios, accumulations will

 generally range from 1 to 3 inches area wide.

&&

.LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/...

A northern stream

trough approaches Sunday night, then crosses the area on

Monday. Depending on model of choice, this could actually end up

being a full latitude trough, but for now that detail should

not have much, if any impact on our sensible weather in this

time frame. It appears that the surface based cold front

associated with this trough should be ana-frontal in nature, so

would expect any snow showers (possibly mixed with rain showers

near the immediate coast) to occur behind the front from Sunday

night into Monday.

A deep layered ridge crosses the area Monday night than exits to the

east on Tuesday. It should be dry Monday night into Tuesday as a

result. Depending on exactly how fast the ridge axis slides to the

east on Tuesday, there is some chance for some light snow

North/light rain/snow elsewhere late in the day.

A northern stream trough crosses the area Tuesday night and

Wednesday morning, with a chance of snow across Northern Aroostook

and Somerset and Northern and Central Piscatiquis counties, with and

a chance of rain or snow elsewhere. Northern stream shortwave

ridging builds in later Wednesday, so it should be dry then.

Deep layered ridging crosses the area Wednesday night then exits to

the east on Thursday. It should be dry Wednesday night, then

depending on exactly how fast the ridge axis slides off to the east,

there is the chance for some snow showers across the North and rain

or snow showers elsewhere by late in the day.

Temperatures start out near normal Monday, and should be above

normal Tuesday-Thursday.....

URGENT - WINTER WEATHER MESSAGE

National Weather Service Caribou ME

1022 PM EST Thu Feb 2 2023

MEZ005-006-031130-

/O.CON.KCAR.BZ.W.0001.230203T0600Z-230205T0000Z/

/O.CON.KCAR.WC.W.0001.230203T1700Z-230205T0000Z/

Northern Penobscot-Southeast Aroostook-

Including the cities of East Millinocket, Hodgdon, Sherman,

Millinocket, Medway, Smyrna Mills, Houlton, and Patten

1022 PM EST Thu Feb 2 2023

...BLIZZARD WARNING REMAINS IN EFFECT UNTIL 7 PM EST SATURDAY...

...WIND CHILL WARNING REMAINS IN EFFECT FROM NOON FRIDAY TO 7 PM EST

SATURDAY...

* WHAT...For the Blizzard Warning, ground blizzard conditions

  expected. Total snow accumulations up to one inch. Winds gusting

  as high as 50 mph. For the Wind Chill Warning, dangerously cold

  wind chills expected. Wind chills as low as 60 below zero.

* WHERE...Northern Penobscot and Southeast Aroostook Counties.

* WHEN...For the Blizzard Warning, until 7 PM EST Saturday. For the

  Wind Chill Warning, from Noon Friday to 7 PM EST Saturday.

* IMPACTS...Plan on slippery road conditions. Widespread blowing

  snow could significantly reduce visibility. The hazardous

  conditions could impact the Friday morning and evening commutes.

  Isolated to scattered power outages are possible. The dangerously

  cold wind chills could cause frostbite on exposed skin in as

  little as 5 minutes.

* ADDITIONAL DETAILS...In addition to low wind chills, areas of

  blowing snow could cause whiteout conditions, particularly across

  open areas exposed to northwest winds. Blowing and drifting snow

  could make travel very difficult. If you must travel have a winter

  survival kit and if you get stranded, stay in your vehicle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Chill Warning means the combination of very cold air and the

wind will create dangerously low wind chill values. Frostbite can

occur quickly and even hypothermia or death if precautions are not

taken.

Persons should consider delaying all travel. If travel is absolutely

necessary, drive with extreme caution. Consider taking a winter

storm kit along with you, including such items as tire chains,

booster cables, flashlight, shovel, blankets and extra clothing.

Also take water, a first aid kit, and anything else that would help

you survive in case you become stranded.

Keep pets indoors as much as possible.

&&

$$

URGENT - WINTER WEATHER MESSAGE

National Weather Service Caribou ME

1022 PM EST Thu Feb 2 2023

MEZ005-006-031130-

/O.CON.KCAR.BZ.W.0001.230203T0600Z-230205T0000Z/

/O.CON.KCAR.WC.W.0001.230203T1700Z-230205T0000Z/

Northern Penobscot-Southeast Aroostook-

Including the cities of East Millinocket, Hodgdon, Sherman,

Millinocket, Medway, Smyrna Mills, Houlton, and Patten

1022 PM EST Thu Feb 2 2023

...BLIZZARD WARNING REMAINS IN EFFECT UNTIL 7 PM EST SATURDAY...

...WIND CHILL WARNING REMAINS IN EFFECT FROM NOON FRIDAY TO 7 PM EST

SATURDAY...

* WHAT...For the Blizzard Warning, ground blizzard conditions

  expected. Total snow accumulations up to one inch. Winds gusting

  as high as 50 mph. For the Wind Chill Warning, dangerously cold

  wind chills expected. Wind chills as low as 60 below zero.

* WHERE...Northern Penobscot and Southeast Aroostook Counties.

* WHEN...For the Blizzard Warning, until 7 PM EST Saturday. For the

  Wind Chill Warning, from Noon Friday to 7 PM EST Saturday.

* IMPACTS...Plan on slippery road conditions. Widespread blowing

  snow could significantly reduce visibility. The hazardous

  conditions could impact the Friday morning and evening commutes.

  Isolated to scattered power outages are possible. The dangerously

  cold wind chills could cause frostbite on exposed skin in as

  little as 5 minutes.

* ADDITIONAL DETAILS...In addition to low wind chills, areas of

  blowing snow could cause whiteout conditions, particularly across

  open areas exposed to northwest winds. Blowing and drifting snow

  could make travel very difficult. If you must travel have a winter

  survival kit and if you get stranded, stay in your vehicle.

PRECAUTIONARY/PREPAREDNESS ACTIONS...

A Wind Chill Warning means the combination of very cold air and the

wind will create dangerously low wind chill values. Frostbite can

occur quickly and even hypothermia or death if precautions are not

taken.

Persons should consider delaying all travel. If travel is absolutely

necessary, drive with extreme caution. Consider taking a winter

storm kit along with you, including such items as tire chains,

booster cables, flashlight, shovel, blankets and extra clothing.

Also take water, a first aid kit, and anything else that would help

you survive in case you become stranded.

Keep pets indoors as much as possible.

&&

$$

Hazardous Weather Outlook

National Weather Service Caribou ME

256 PM EST Thu Feb 2 2023

MEZ005-006-032000-

Northern Penobscot-Southeast Aroostook-

256 PM EST Thu Feb 2 2023

...BLIZZARD WARNING IN EFFECT FROM 1 AM FRIDAY TO 7 PM EST

SATURDAY...

...WIND CHILL WARNING IN EFFECT FROM NOON FRIDAY TO 7 PM EST

SATURDAY...

This Hazardous Weather Outlook is for Central Highlands Maine and

Far Eastern Maine.

.DAY ONE...This afternoon and tonight.

Please listen to NOAA Weather Radio or go to weather.gov on the

Internet for more information about the following hazards.

   Blizzard Warning.

.DAYS TWO THROUGH SEVEN...Friday through Wednesday.

Please listen to NOAA Weather Radio or go to weather.gov on the

Internet for more information about the following hazards.

   Blizzard Warning.

   Wind Chill Warning.

.SPOTTER INFORMATION STATEMENT...

Weather spotters are encouraged to report significant weather

conditions according to Standard Operating Procedures.

$$

11:13 PM AST Thursday 02 February 2023

Extreme Cold Warning in effect for:

Halifax Metro and Halifax County West

A period of very cold wind chills is expected.

On Friday, an arctic airmass will combine with strong northwest winds to give bitterly cold conditions. Windchill values of minus 35 to minus 42 are expected to develop Friday night and will persist into Saturday morning before beginning to moderate Saturday afternoon as winds subside.

Watch for cold related symptoms: shortness of breath, chest pain, muscle pain and weakness, numbness and colour change in fingers and toes.

Cover up. Frostbite can develop within minutes on exposed skin, especially with wind chill.

Extreme cold warnings are issued when very cold temperatures or wind chill creates an elevated risk to health such as frost bite and hypothermia.

Information is provided on the Nova Scotia Department of Health and Wellness website at https://novascotia.ca/nse/environmental-health/staying-warm-in-winter.asp.

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.

11:11 PM AST Thursday 02 February 2023

Extreme Cold Warning in effect for:

Fredericton and Southern York County

The coldest wind chill values will be near minus 45.

On Friday, an arctic airmass will combine with strong northwest winds to give bitterly cold conditions. Windchill values of minus 35 to minus 45 are expected to develop Friday afternoon and will persist into Saturday morning before beginning to moderate Saturday afternoon as winds subside.

Watch for cold related symptoms: shortness of breath, chest pain, muscle pain and weakness, numbness and colour change in fingers and toes.

Cover up. Frostbite can develop within minutes on exposed skin, especially with wind chill.

Extreme cold warnings are issued when very cold temperatures or wind chill creates an elevated risk to health such as frost bite and hypothermia.

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.

11:11 PM AST Thursday 02 February 2023

Extreme Cold Warning in effect for:

Queens County P.E.I.

A period of very cold wind chills is expected.

On Friday, an arctic airmass will combine with strong northwest winds to give bitterly cold conditions. Windchill values of minus 35 to minus 40 are expected to develop Friday night and will persist into Saturday morning before beginning to moderate Saturday afternoon as winds subside.

Watch for cold related symptoms: shortness of breath, chest pain, muscle pain and weakness, numbness and colour change in fingers and toes.

Cover up. Frostbite can develop within minutes on exposed skin, especially with wind chill.

Extreme cold warnings are issued when very cold temperatures or wind chill creates an elevated risk to health such as frost bite and hypothermia.

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.