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    Four Days of Quiet Weather, Then a Turn to Storminess

    12/11/2012, 7:25:49 AM

    Tuesday, 11:30 a.m.

    It is not often that you see severe weather in the middle of December, but we saw that yesterday and into last night with and ahead of a cold front in parts of Louisiana and Mississippi, as well as in parts of northern Florida. The cold front that was moving steadily across the Southeast yesterday was tied to a storm moving through southern Quebec, one that is now streaking away from Labrador into the Northwest Atlantic.

    As storms go, it wasn't the strongest one you'll see during the course of the winter season, yet it managed to dump over a foot of snow on parts of Minnesota over the weekend. That could well be the start of the expansion of the snow cover across the country, one that has been conspicuous by its absence up to now. Here's a look at the morning snow cover analysis:

    Notice, though, the lack of snow on the ground, or the minimal snow cover, over southern North Dakota, western South Dakota, and much of eastern Montana down into eastern Colorado. A close-up view of the region from NOAA:

    What are the prospects for seeing this snow pack expand? In the next few days, nearly nil. If you look at the infrared satellite picture from this morning, you can see the development of another wave of low pressure over the Gulf of Mexico with the baroclinic leaf signature:

    This feature is forming on the back side of that cold front, and it will cause some rain to redevelop over the northern Gulf and into the Florida Panhandle and southeastern Alabama late this afternoon and tonight. Rain will then expand northeastward through southern and eastern Georgia and South Carolina and may ultimately graze extreme southeastern Virginia for a time late tomorrow and tomorrow night before that wave of low pressure departs and takes all of the moisture with it late tomorrow night and Thursday. Regardless, all of that moisture will be in the form of rain, not snow, so it will have no contribution to the expansion of snow cover across the country.

    Instead, we'll have to turn our attention to the West for the next storm to develop. Looking back at that satellite image, you can see some of the initial moisture from that developing storm move into the Northwest at this hour. The main body of the upper-level disturbance, though, is off the coast and will move southeastward this afternoon and tonight. In the process, it will bring some rain and higher elevation snow to Washington, Oregon, parts of Idaho into northern California.

    Showers associated with this feature will move through central and southern California, as well as portions of Nevada into Utah and Arizona tomorrow night and Thursday. Of course, that will lead to some snow in the mountains, including the Sierra. By the end of the day Friday, that feature will be rolling through the southern Rockies, causing low pressure to emerge over southeastern Colorado and southwestern Kansas. There could be some snow in Colorado later Friday and Friday night, but the air mass farther east on the Plains may not be cold enough initially to support snow.

    With time, though, this feature will intensify to the point where the air north of the track of the storm will become cold enough for snow. Given the projected track of the storm into the Great Lakes Saturday and Saturday night, that means snow is likely across portions of Iowa and Minnesota into Wisconsin and northern Michigan. Most areas farther south and east will see nothing but rain, with one notable exception.

    That exception will be upstate New York and the northern half of New England. The will be enough cold air in place ahead of the storm so that when precipitation streaks in Saturday night and Sunday, it'll start as snow in many areas. The storm, will come so far northeast before giving way to a secondary storm near the coast of southern New England some time Sunday. In turn, it will likely stay cold enough across much of Vermont, New Hampshire and Maine for the precipitation to remain largely as snow in those areas. Considering how little snow is currently on the ground there, this will be a welcome thing for the ski resorts:

    The weekend storm will be the first in what should be a series of storms leading up to Christmas. The next one in the pipeline starts to gel Monday across the southern Plains and lower Mississippi Valley. Its fate is yet to be determined, but there could well be enough cold air north of the track of that storm to bring snow into the discussion from the mid-Mississippi Valley, if not parts of the central Plains, all the way to the Northeast, including parts of the Ohio Valley.

    For what it's worth, the GFS is suggesting there's still another one that follows the weekend before Christmas. For those 'dreaming of a white Christmas,' here's the GFS for Sunday morning, Dec 23:

    That's all I will say on the subject today. Suffice it to say that even though the overall picture remains milder than normal on average between now and then, there will be a couple of opportunities to expand the snow pack across the country.

    The views expressed are those of the author and not necessarily those of AccuWeather, Inc. or AccuWeather.com


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