These details are provided by the NWS offices in Gray Maine, and the surrounding NWS offices in New York, and Massachusetts.  I have modified some of the technical stuff to help make it more understandable for the average reader. Spelling and grammer issues can be directed to the NWS office in Gray Maine.

Last update: 2/02 - 5:07 PM

NEAR TERM /THROUGH TONIGHT:

Mid to upper level clouds continue to stream across the area this afternoon, with a few scattered snow showers across far northern areas. Some decrease in cloud cover is expected this evening before an arctic frontal boundary approaches the area. Temperatures remain fairly mild most of the night ahead of the front, with temps in the mid 20s to low 30s.

Things change in a hurry after midnight with the arrival of the much talked about arctic front. Scattered snow showers and squalls are likely through the mountains late this evening and a couple hours after midnight with the passage of the arctic front. These quickly diminish in intensity as they move past the mountain, with only scattered snow shower activity making it down wind of the mountains later tonight.

Temperatures quickly tumble behind the front on a gusty northwest wind. Temperatures are expected to fall to near -10 degrees along the Canadian border by sunrise tomorrow, with wind chills falling below -30. Closer to the coast, temperatures will be falling into the single digits during this timeframe with wind chills approaching -10. Sustained winds around 20mph are expected, with gusts around 30mph.

SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT:
Temperatures continue to steadily fall during the daytime tomorrow, with temps falling below zero along the coast during the afternoon hours and wind chills in the -20s. Temps near -20 with wind chills around -40 expected across northern areas during this timeframe.

Temperatures continue to fall tomorrow night as the cold becomes downright dangerous. The center of the polar vortex is expected to cross the area late tomorrow evening and shortly after midnight, with temperatures dropping through after midnight.

An unusual phenomena for our area is possible tomorrow night, with guidance indicating that the tropopause could dip below the peak of Mount Washington tomorrow night. While extremely rare, the impact of this is that winds are likely to increase during the overnight as the the wind becomes more compressed through the lowest levels of the atmosphere. Combined with the bitterly cold temperatures, wind chill values likely fall to as low as -60 across northern areas, and -40 to -45 along the coastline. Although unofficial, from the records we have been able to gather, the coldest wind chill in Portland since 1948 was -43 degrees in 1971, so we are nearing wind chills values that most have not seen in their lifetime.

The danger of the this cold needs to be emphasized. Time for frostbite to develop in these conditions is 10 minutes or less, and 5 minutes or less with wind chill values below -50. Traveling tomorrow night could become deadly should vehicle troubles arise. Cars have more problems in the cold weather, whether its from dead car batteries, diesel fuel gelling in diesel equipment, or significantly reduced range in electric vehicles. People should dress and pack clothing to survive the temperatures outdoors, not for inside the car or for where they are planning on traveling. Cell phone batteries can also die very quickly in the cold, so these may not work properly once exposed to the cold for a few minutes.

Additionally, wind gusts to 40mph tomorrow night could cause a few power outages, especially in and around the mountains. While outages are expected to remain widely scattered, anyone that does lose power and does not have a back up heating system will see their indoor temperatures quickly fall and the risk of frozen pipes quickly increase. Now is the time to know where your water shutoff is located and to have a plan should you lose power.

LONG TERM /SATURDAY THROUGH THURSDAY:
A very cold start to the extended is expected Saturday as a highly anomalous cold air mass will be overhead. Winds will remain quite strong Saturday morning still, so wind chill values will greet the day well below -30F. Winds will diminish during the afternoon hours. Dry weather is expected.

The good news is that this air mass is fleeting. Rapid WAA(Warm Air Advection) takes place Saturday night and Sunday as a warm front lifts northward. A few snow showers may occur with the front, especially in the north. Temperatures Sunday will experience quite the rebound, with highs in the 20s north and 30s/40s south. It`ll probably feel like "summer" Sunday afternoon to many folks.

A cold front moves through Monday but it`ll be nothing like the one coming through late tonight. Highs Monday will be in the 35 to 45 degrees range for most locations along with some mountain snow showers possible.

High pressure moves overhead Monday night into Tuesday before moving offshore Tuesday afternoon and night. Most guidance expects a short wave trough to move through late Tuesday and Tuesday night with a chance of rain and snow showers.

The next chance of appreciable precipitation looks to arrive Thursday or Friday, with confidence in time of arrival quite low at this time.

CLIMATE... A near historical cold air outbreak remains is expected beginning early Friday. While this event is forecast to be significant with respect to ambient surface temperatures, long- standing benchmarks concerning apparent temperatures (wind chills) and the air mass itself will be challenged. The 00Z Saturday (7 PM EDT Friday) upper air sounding is the most likely balloon launch to challenge unofficial records for KGYX with 850 mb temperatures expected around -30 to -35 C. Both and 00z and 12z Saturday (7 PM EDT Friday and 7 AM EDT Saturday) upper soundings may challenge unofficial 925 mb temperature records with readings between -25 and -30 C. Wind chill values will be lowest Friday night and Saturday morning and may be the coldest or colder since a similar event in February of 2016. If wind chills fall to -40 or -50F this will be the first time in 20 or 30 years for many locations. Records for low temperatures are less likely to be broken, given past radiational cooling events with no wind have result in very cold temperatures for a short time. Cold daytime high temperature records do show some potential to be broken on Saturday the 4th.

KGYX Sounding Climatology - 850 mb Temperatures *
Min 10th perc. Median
Feb 3 12Z (7 AM Fri) -22.2 C -16.66 C -8.18 C
Feb 4 00Z (7 PM Fri) -23.4 C -16.64 C -8.17 C
Feb 4 12Z (7 AM Sat) -24.0 C -16.62 C -8.16 C
All time record low of -31.7 C

KGYX Sounding Climatology - 925 mb Temperatures *
Min 10th perc. Median
Feb 3 12Z (7 AM Fri) -24.3 C -14.03 C -6.05 C
Feb 4 00Z (7 PM Fri) -18.6 C -14.01 C -6.04 C
Feb 4 12Z (7 AM Sat) -24.1 C -13.98 C -6.03 C
All time record low of -26.6 C

Record Cold High Temperatures
Portland Concord Augusta
Sat 4th 9 (1948) 4 (1908) 6 (1963)

Record Low Temperatures
Portland Concord Augusta
Sat 4th -19 (1971) -24 (1898)-14 (1971)
Sun 5th -13 (1978) -16 (1978) -10 (1996)

Last Date Since High Temperature <= 10 F
PortlandJan 06 2018 (4 F)
ConcordJan 15 2022 (8 F)
AugustaJan 15 2022 (10 F)

Last Date Since Wind Chills <= -35 F *
PortlandJan 04 1981 (-36 F)
ConcordFeb 13 2016 (-39 F)
AugustaJan 16 2004 (-37 F)

* It is important to note that official climate records are NOT kept
for apparent temperatures and upper air soundings, and are therefore
NOT subject to the same rigorous quality control processes as our
normal subset of climatological information.