'Twas the Week Before Christmas

Just a very brief post to alert y'all that the American modeling is hinting at a period of unrest for the atmosphere the week before Christmas.  As we move deeper through December, the average temps decrease compliments of a lowering sun angle and a shortening day.  Couple that with increased snow cover over North America and the winter season will be upon us very quickly the next several weeks.  Here is the current snow and ice coverage over North America.  Note how the Chinook (down-sloping and warming winds on the east side of the Rockies) helps clear snow in the Canadian prairies and in our plains states as well.

This week will feature tranquil weather compliments of an upper air ridge and surface high pressure for the bulk of this week.  That is a rather extensive upper ridge extending out from the Gulf of Mexico and flexing its muscle all the way up into New England and Ontario.

But lurking back in the SW USA is that pesky trough that will start to send pieces of energy out eastbound.  The first possible threat is next weekend as a weak wave passes off to our south.

I believe yet another boundary or front will set up as shown where the green precip is falling and waves of low pressure will spin up along that boundary subsequently pulling colder air towards the SE states.  The modeling hints at a second wave that is getting some energy as shown below.  This is later Monday of next week.

Then comes the dandy; the "Big Dog" so to speak...ruff, ruff!  High to the north, low pressures in the southern states, a digging upper trough and we may just, just might have a White Christmas.  Hello, bingo front row!  Be aware, this could also as easily not even materialize or pull much further west based on where the boundary decides to set up shop.  After all, this is 11 days hence.

Just for kicks and giggles and for the sake of climatology. Here are the statistical averages of seeing snow on the ground for December 25.  Living in the Koeppen sub-tropics, we experience snow on the ground in late December about 1 out of every 5 Christmases, not very good odds!

So kick back, relax, and enjoy this holiday classic as we prepare to celebrate this 2011 Christmas season.  This weekend's briskness (coldest days for the last 21 at KMDT!) will help get your weather spirit going, unlike my blown call for a plowable storm earlier this week...it hurts will continue to hurt for quite awhile!

GO RAMS!

Smitty

AA:  Tranquil week upcoming, but unsettled with snow possibilities the week before Christmas.  Good chance for the CD RAMS to be playing at Hershey next weekend....in a snow event???!!!