Ski Weather - March 13, 2010

When the last significant coastal storm came into the Northeast, in late February, the amount of cold air hanging around was just enough to produce monumental amounts of snowfall in the mountains. Here we are two weeks later, and another complex storm is impacting the country from the Mississippi River Valley to the East coast. Now, because Canada has been milder than normal for the past couple of weeks and there has been no discharge of fresh cold air from the polar regions, this new storm is going to be predominantly a rain producer, and some areas are going to lose a good deal of base snow as a result.

The resorts of far northern New York and northern New England are going to dodge a bullet with this one...the bulk of the moisture with this storm will squeeze out to sea to the south...there will be some mixed precip well to the north, but it will be more of a nuisance than anything else. The Midwest has had a very quiet winter, weather-wise, but it looks as though that region will have one more shot at meaningful natural snow. And speaking of snow...a bit of a pattern change has brought fresh snow to the Pacific Northwest this week, and the interior ranges of the West are picking up some heavy snow this weekend, after the coastal ranges of California got hit hard on Friday. Cold air is still at somewhat of a premium across the country, but the same pattern change that has brought snow to the West is the first sign that the jet stream will realign and deliver one last shot of arctic air to the U.S. before spring starts to settle in for good.

Here's a look at the jet stream pattern on Saturday morning, the 13th...

The upper level low that looks like a bowling ball is responsible for the wet weather that is dampening the slopes from the Carolinas into southern New England this weekend. If you follow the lines on the map, you'll notice that there is nothing resembling a flow into the U.S. from Canada. That's the problem with the eastern storm...not enough cold air, due to a blocking pattern persisting over Canada. The sharp short wave trough over Idaho and Nevada is swinging in from the Pacific and delivering a nice shot of fresh snow to a good portion of the West this weekend, although it will weaken a bit as it runs into the short wave ridge that you can see stretching from western South Dakota down towards El Paso. Nevertheless, 1 to 2 feet of powder will pile up in Utah this weekend, which should placate the powder hounds.

The western trough will move east early in the week of the 15th, helping to sustain a broad trough over the eastern half of the country. Overall, the upcoming week will be rather benign in the eastern half of the U.S., once the lumbering storm moves off the east coast on Monday. An upper level ridge will develop over much of the West, which will produce some great weather to enjoy the fresh snow early in the week. By midweek, a new trough will make landfall in the Pacific Northwest, and the second moderate snowfall in about a week will take place in the Cascades, with lighter snows spreading into the northern Rockies.

The next big change in the pattern will get underway late in the week, and the trigger will actually be a sequence of events in Alaska. A strong upper trough has been situated over Alaska for several weeks, where very cold temperatures have been building. That trough will slide south of Alaska this week, which will help to build an upper level ridge in western Canada. That ridge will then produce a northwesterly flow over much of central Canada, and short wave energy from the retreating Alaskan trough will move up and over the crest of the ridge, descend through Canada and into the U.S. A surface low will form in the Plains in response to the approaching short wave, and that low will move up through the Great Lakes over the weekend of the 20th/21st. To the west of the storm track, fresh snow will fall in much of the upper Midwest, while another weekend of spring skiing and riding will be played out in the East. The surface low will send a cold front through the East late on the 21st or on the 22nd, and some true arctic air will follow on its heels. The core of the cold will be in the Midwest, but the week of the 22nd will be colder than normal over the eastern two thirds of the country, which, at a minimum, will help to preserve the snow on the slopes. With a new trough in place that contains some bonafide cold air, the potential for late season snowfall is enhanced. That cold air will hang around for 7 to 10 days, and then it looks as though the jet stream will take on more of a west to east configuration, which will essentially bring an end to winter in the East...April does hold some promise for late season snow in the West, as it will be easier for Pacific troughs to come ashore in a fashion similar to what we are seeing this weekend.

REGIONAL SUMMARIES:
NORTHERN ROCKIES/NORTHERN COASTAL RANGES/WESTERN CANADA
These areas picked up a nice shot of snow during the week of the 8th, and it looks as though a similar system will arrive around the 17th or so. Beyond that, an arctic short wave will glide down the eastern slopes of the Rockies just prior to the weekend of the 20th/21st. The coastal ranges will miss out on the new snow with the late week system, but the pattern change that follows will make it easier for Pacific systems to deliver moisture and cold air to the Cascades later this month.

SOUTHERN COASTAL RANGES/SOUTHWEST
Another potent system is plowing through the region south of I-80 this weekend, with 1 to 2 feet of new snow to be expected in Utah, with over a foot on the way to southwest Colorado and northern New Mexico, as well. Much of the upcoming week will be quiet, but a northern trough will move down the Rockies next weekend, generating another round of snow from the Wasatch southward to Arizona and New Mexico, providing the region with another late season powder day.

CENTRAL ROCKIES
Snowfall has picked up in this region of late, and the prospects look good for the next week or so. Moderate snow will fall this weekend, followed by several "bluebird" days, before a trough arrives from the north next weekend, when additional snow will fly. It took a long time, but conditions in this region have shaped up nicely in the past couple of weeks, and it's looking good through the rest of this month.

UPPER MIDWEST
This week will be a little milder than normal, which may cause a few resorts to pack it in, as base depths are getting a little lean in spots. Next weekend will bring a pattern change after low pressure cuts through the central Great Lakes. Significant snow will fall to the west of the track of the storm, with Minnesota, Wisconsin, and the UP of Michigan likely to benefit the most. The following week will be well below normal, with temperatures favorable for preservation of base snow, and additional light snow is a good bet as one or two Alberta Clippers move through the region. The pattern change will show up just in time to sustain the season in this region.

MID ATLANTIC/SOUTHERN APPALACHIANS
Thankfully, the bulk of the moisture associated with the weekend storm moved up through the coastal plain and not along the spine of the Appalachians. Rain did fall in the mountains, but all it did to the amazingly deep bases is change the surface snow. Higher sun angles are taking their toll on the bases in this region, but they have enough snow to sustain the season deep into this month, and perhaps to Easter Sunday, without too much trouble...the arrival of colder air late next weekend will help.

NORTHEAST/EASTERN CANADA
Much of the precip from the weekend storm is rain below 1,500 feet, with rain, sleet, and snow falling in the highest elevations. Lower elevation resorts in eastern Pennsylvania will receive several inches of rain, and trail losses are almost certain. As the storm slowly pulls away on Sunday/Monday, there will be some accumulating snow from the Poconos northward through the Catskills and into the mountains of northern New England, where precip totals will be light, due to the blocking of dry high pressure to the north. A nice week of spring skiing and riding will follow the passage offshore of this storm, and the weekend of the 20th/21st looks like a fine one for spring snow and special events on the snow. Colder air will arrive around the 22nd, with a colder than normal week to follow...one that holds promise in terms of natural snow, as well.