Here we go again.  For the third weekend in a row another coastal storm is poised to affect the area.   There are some differences between this storm and the past two.   Prior to this storm warm air will try to flow north and will impact the position of the rain/snow line.   Here in New England, winter storms have both cold and warm air as part of their formation.  In simplistic terms the left side of the storm is cold and the right side is warm.  The closer the center of the storm comes to the coast, the closer the warm air.  

For our weekend storm, the track is going to be critical.  While the track of the storm is certainly important, there are many other factors besides the exact track that can impact the type of precipitation an area ultimately receives.  First, if there is a lot of cold air before the storm begins then it can take longer for any change to rain to occur and for warm air to move inland. Second, this time of the year the ocean water is nearing its yearly minimum.  Unlike 6 weeks ago when ocean temperatures were running above normal, ocean temperatures now are colder and are quite typical for the latter half of February.  The colder ocean means if we do see a wind coming from the east, off that water, the mild marine air won’t move as far inland and the precipitation remains all snow closer to the coast.  Third, the time of day the storm occurs can be very important.  It’s much easier to have a storm’s precipitation remain all snow at night than it is during the day.

I’ll be updating the forecast all day on Twitter at @growingwisdom please send me your reports there.

Our storm this weekend will begin early Saturday evening with the bulk of the storm coming at night through the first few hours of Sunday. Based on some of the reasoning above, areas close to the coast may start as a mixture of rain and snow and then change to snow as the night progresses.  We have had storms in the past where the rain/snow penetrates west of Portland and up through Rockland for a few hours, and then turns around and collapses to the coast several hours later. The stakes are high with this storm.  Current model forecasts give up to an inch and a half of precipitation which can translate into over a foot of snow if rain was not involved with the storm.

The best chance for the heaviest amounts of snow will be west of the Maine Turnpike and south of Lewiston.  This doesn’t mean Portland, Rockland, Kennebunk or York aren’t going to see snow or even significant amounts of snow, it just means the most likely areas to get all snow and no rain are north and west of those areas.  We will have a wind off the water, especially in the first few hours of the storm.  I am concerned that many coastal communities will experience a period of rain, or mixed snow and rain, for several hours as the storm begins.  This will cut down on accumulation.  I am confident the rain will not move very far inland. 

The trend Saturday night into early Sunday will be for any rain or mixed snow and rain to change to snow.  The snow will be heavy and wet along the coast for a time.  This will cause the snow to stick to everything and when combined with strong winds, some power outages might be an issue. Additionally, the strong winds will need to be monitored as coastal flooding around the time of high tide, about 10 AM Sunday, is possible.

The storm will wind down on Sunday in the form of snow.  The snow will tend to be drier and fluffier for the second part of the storm.   Dry weather will return later Sunday and continue into Monday before the next storm threatens the area Wednesday.  The current pattern of these storms looks to continue for about another week to 10 days.  I can’t say how strong any future storms will be after this weekend, but I can tell you that the jet stream remains very active and that March will enter like a lion across much of the country.

Gardening this week: With another storm on the horizon for the weekend you might feel like spring is still very far away. The reality is that in just a few weeks, many of you will be able to get into your gardens and start growing for another year. Earlier this month I went to New England Grows, which is a trade show for those who work in the industry. Although not open to the general public, in this week’s video I share some of the latest trends and newest plants for 2013.

I’ll be updating the forecast all day on Twitter at @growingwisdom please send me your reports there.