Wednesday, May 22, 2013
A blizzard warning is in effect for much of coastal Maine. This means that winds in excess of 35 miles per hour and low visibility from heavy snow will occur for 3 or more hours during this storm.
A wobble closer to or farther from the coast could ultimately change accumulations by a bit, but it's going to be a big storm no matter how you slice it.
Here is the timing on the storm right now. I expect snow to break out in the early afternoon Friday. The core of the storm will move in Friday night and the first half of Saturday. Winds will increase and blow the snow into big drifts.
Coastal communities are going to have to watch carefully the high tide Friday evening around 10 and Saturday morning around 10. The tide Saturday morning is more than a foot higher than Friday night's.
The exact position of the storm will determine the extent of any coastal damage. Friday night I expect roads to become virtually impassable as the snow falls at rates of 1 to 3 inches per hour. The snow will continue Saturday morning and finally come to an end during the afternoon. The snow will not be heavy and wet, so at least moving it won't be quite as difficult as it could be.
When this is all over, some areas will have 2 feet of new snow on the ground. I'll be updating the forecast throughout the storm on Twitter at @growingwisdom and showing my latest maps.
There have been very few times over recorded weather history that Portland has received over 2 feet of snow in a single storm. Back in January 1979 a storm of light fluffy snow ended up giving the city just over 27 inches of powder. That particular storm isn't very memorable to many because it didn't do a lot of damage to the shoreline nor did it cause widespread power outages. I do remember the storm because I didn't have school for three days.
Thirty-five years ago, the famous Blizzard of 1978 pounded southern New England with nearly 4 feet of snow in places, but here in Maine a foot was more common. However, that storm was memorable because of the damage it did to the Old Orchard Beach Pier. From Feb. 24-28, 1969, it snowed for nearly 100 hours and Portland again ended up with about 27 inches of snow. Those storms are some of our largest to ever hit southern Maine, and now we are looking at another potentially historic storm on the horizon.
I use the word historic for a storm that ends up as one of the top 10 largest on record. Friday's storm will impact all of southern Maine, but for it to become historic every key ingredient in the atmosphere must come together in just the right way. Snowfall rates will need to approach 3 inches per hour at least for a few hours. If, for example, it snows at 1 inch per hour from midnight until 5 a.m., that will give us 5 inches of snow. But imagine getting 3 inches per hour during that time. Now you're adding 15 inches to your total. For Portland and other towns to see final amounts over 18 inches we have to have some incredibly intense snowfall rates for at least part of the storm.
For a storm to end up in the official blizzard record books its winds must remain sustained at 35 mph or higher and coincide with the very intense snow. Visibilities under 1/4 mile must be recorded for three hours or longer. Sometimes, in storms like these a town such as York can experience blizzard conditions while in Sebago, 40 miles away, winds are just under the blizzard threshold. We won't know who, if anyone, ends up in a full-fledged blizzard until the storm is under way. There have been many storms with near-blizzard conditions, but very few ever reach blizzard criteria over a wide area.
When the storm is over Saturday afternoon how bad it was will be a matter of some subjectivity. If you don't lose power and the worst you have to do is shovel a lot of snow, you might think the storm wasn't so bad. If a tree falls on your car or your house the storm becomes more memorable for you and your family. For anyone who loses an entire home, or God forbid their life, the storm is catastrophic.
This is the hard part of forecasting and conveying what the storm will be like before it occurs. Everyone has a different opinion on what makes a bad storm. For some, unless the entire East Coast is shut down for a week, they'll think the storm wasn't so bad. For others, not being able to go shopping Saturday is a catastrophe. I tend to fall in the middle somewhere. The reality is that nearly everyone who reads this will come through the storm Saturday night about the same as they went into it. Will this storm be a footnote in an otherwise tranquil winter, or a blockbuster storm that begins a snowy second half of winter, or will it indeed be historic? I'll continue to work through those answers the next few days.
This week I am putting up a video on how to build the perfect container. While you might not be thinking of gardening this week, you can plant pansies in 8 weeks and if you have protective covering some vegetables can be planted in another 5 weeks. More on how I do that in upcoming blogs.
David Epstein has been a meteorologist for more than 25 years. He spent 16 years in Boston and currently freelances at WGME13 in Portland.
In 2006, David founded GrowingWisdom.com, a business producing educational and marketing videos for the green industry. He currently is a professor at Framingham State College, teaches Jan Plan at Colby College and owns Bloomscapes Inc., a landscape design business.
David authored "Gardens Of New England" and his work has been published in Grolier's Science Annual for 10 years. He lives in South Natick, Mass., and has a summer home in Harpswell.