Evening Update:

Snow overspread the area this morning and afternoon and is now quite steady. The progress of the storm looks to be on schedule with more heavy snowfall on the way overnight. In looking at some of the data, it appears about 10-16 inches of snow of the total we receive will fall from about 9 p.m through about noon on Monday. After noon, any additional snowfall will be light and insignificant.

The radar loop below runs through 8 a.m. Monday. By that time, you can already see the back edge of the snow pulling into extreme southwest Maine.  This will mean the storm is coming to an end.

Snow will fall heavily overnight ending Monday morning.

Winds are still going to be strong and gusty tomorrow and will actually peak after the snow finishes. However, blizzard warnings are up east of Brunswick and do not include Portland.

Southern most Maine is not included in a blizzard warning tonight.

The storm looks like it will gain most of its intensity just a bit later than expected. This means that an official blizzard isn’t likely in southern most Maine.

Earlier Update

A new winter storm will pack a one-two punch as it heads into Maine today, starting with a wave of light to moderate snow before bands of snow and wind wallop the region on Monday.

This storm is more complicated than others we’ve seen this season. The initial push of snow is well forecast, but the backlash snow Monday may be further north and east than expected yesterday. This would put the heaviest snowfall totals just north of southern Maine and more in the midcoast or Down East region. 

The models are a a great guide to make a forecast, but one can’t rely on any one of them too much. It now comes down to old-fashioned experience, nowcasting (watching the weather hour-by-hour) and a bit of intuition.

A large storm will form over the next 24 hours, bringing blizzard conditions to some areas of coastal Maine.

The first half of the storm gets underway Sunday afternoon as the low-pressure system moves from land toward the coastline south of New England. As this happens, snow will break out across the area. I expect the snow to become heavier and steadier, with several inches likely on the ground by 7 or 8 p.m. 

Overnight the storm will continue to intensify and bring moisture into the area. Snow will increase in intensity so when you get up Monday it should be snowing at rates of 1 to 2 inches per hour. Some areas may even see some thundersnow.

On Monday, as the storm intensifies and throws more moisture back into eastern New England, snow will continue to accumulate. This is the most difficult and least reliable part of the forecast. If the backlash snow – snow on the western side of a storm – is intense, Portland and much of the area will see a lot more heavy snow and totals would exceed 16 inches. A faster-moving storm or a storm that intensifies a bit later would push the heaviest snow farther north.  

Snow will be heavy throughout most of Maine.

The snowfall map is based on backlash snow occurring. Historically, backlash snow is more common in the mountains, but can make it down the coastline.

Powerful, perhaps damaging winds, are likely Monday. Along the coastline, winds could exceed 60 mph in gusts and reach 50 mph inland. These types of winds can topple trees and create power outages. I would recommend being prepared to lose power.

There will be some coastal flooding, but the more northerly direction of the wind during the strongest part of the storm will prevent widespread moderate and certainly major coastal damage or flooding. Winds will be powerful throughout most of Monday.

The blizzard watch in place along the coast may be upgraded to a warning this afternoon as new information becomes available.

A blizzard watch is posted for much of the southern Maine coast, a warning is posted further north.

Tuesday is a much quieter day with less wind and periods of sunshine.

You can follow Dave Epstein on Twitter @growingwisdom