Saturday, January 05, 2013

Potential To Turn Colder After Mid Month Mildness

We effectively wrote off significant cold and snow chances through mid month earlier this week, unless you think a dusting or coating of snow tonight is significant snow and if you think that highs in the 40's and 50's next week is significant cold. The next week to perhaps ten days will feature a trend towards milder conditions before a possible (it's not likely yet) colder turn after the middle of the month.

Using Euro ensemble guidance as a guide, you can see the jet stream pattern as we enter next weekend.  Notice a strong ridge in the Eastern Pacific (spike of yellow and orange) as well as along the East Coast.  This means a milder regime in these areas, with a trough of cold digging down across the Plains.  In general, this results in a pretty mild pattern overhead, with the coldest weather to average generally across the Rockies, Northern Plains, and interior West.  Through mid month, it looks likely we'll be milder than not more often than not.  We can't rule out a colder day here or there but the overall pattern itself supports generally milder weather in the East for the next seven to ten days.

After ten days, the pattern start to change for the colder for us.  We should see steps down towards colder weather after mid month...may not be sudden and dramatic but the overall mild regime that was in place edges a bit colder as ridging increases over Greenland (see the greens pop north towards them) while the trough over the Plains is now a bit more east.  The map below will not be as "strong" in showing oranges and blues given it's an average of the various European ensemble products fifteen days out but it does provide an idea of where the averages are leaning towards.  We should see this colder regime take shape after ten days, probably in place by MLK Day Weekend.

We can't specify dumps of arctic cold into the East although some rumors abound of it.  Figuring the specifics of where the polar vort and troughs set up are still a bit too far out to even really talk about with any level of confidence.  The longer range Euro does suggest a nice chunk of cold air is poised to work into the Midwest and Northern Plains in about ten days time -- some of that may work east as the first shot of this colder pattern in our neck of the woods but modify as it does so.