Thursday, December 20, 2012

General Ideas Of Weather Next Two Weeks

In the wake of tonight's storm, a generally colder pattern sets in. As we've been talking about for the better part of a week, this is not an arctic pattern nor is it anything close to it with what is coming in. However, highs in the 50's and 60's will not be as common as highs in the 30's and 40's.

Yeah, more "typical" December weather is forthcoming.  And, with exception, will be the regime over the next two plus weeks.

A good indicator of where patterns are going to head is by forecasters using an anomaly range map like the ones posted below.  These graphics show a five day (some maps vary) average of where temperatures are going to stack to normal.  Reds are warm, blues are cold.  The first graphic shows the timeframe immediately after Christmas, 12/26-12/30.  You see warmer than average temperatures in Northern Canada, colder than average temperatures in a couple of pockets in the Plains and on the East Coast, with the Dakota pocket the only significant cold zone on the map.  This would suggest that temperatures over that timeframe would average slightly cooler than normal overall.  It doesn't mean every day will, however.

One important note is that a storm system is modeled to be in our vicinity next Wednesday night into Thursday -- timing, track, details still vary but the GFS and Euro are both showing a storm system tracking through the East Coast.  If the storm ends up taking a track similar to our storm tonight we probably end up seeing rain and temperatures in the 50's, with a return to cold in the wake of the storm.  Some modeling has tried to squeeze a more favorable track for cold and snow for the Poconos and areas north and west of Philadelphia but given our spot a week plus out, predicting specifics is of very low confidence.  Just be aware that if you're travelling late Wednesday into Thursday next week there will be some sort of storm system around.  We'll show some maps on it tomorrow and through the weekend.

As we push into the New Year, the signal for colder air continues to show up in the longer range ensembles. The GFS (and Euro as well) show the idea of cool to colder than average for a good chunk of the country, with the coldest now shifted to the East Coast from the Midwest.  Again, we're not talking mega-Arctic with highs in the teens type cold, but 30's for highs certainly wouldn't be out of the realm of possibility.  Typical to below average cold for the beginning of the year.

Using these anomaly maps isn't completely foolproof when looking at what reasonable weather will be over the coming weeks but it does give us a decent idea as to what is forthcoming -- and for those of you sick of the mild pattern, take solace in the fact that if modeling is correct, December ends quite unlike it began.