Wednesday, December 21, 2016

Weather It Is (Winter)

Good Afternoon:

After taking a back seat to fall (some might even thought spring temperatures) winter has arrived.

There is a chill in the air and there are frequent periods of rain.

Looking at today's weather map, we see strong winds tonight as an upper level disturbance passes by to our northwest.  This should bring a period of rain along the NW coast.

By Shabbat, temperatures will fall again, and a heavier rain should arrive (again with strong winds). The storm system that will bring the next bout of winter weather can be clearly seen on the GEFS mean maps (on our site) in both cold upper air temperatures and strong vorticity advection. Temperatures in the upper atmosphere will below - 25 C, but temperatures in the middle and lower atmosphere will be relatively warm (for snow, meaning rain). The storm is actually passing over the sea after heading down south from past western Turkey, so this will ameliorate the low level cold normally associated with type of system.  Still, this type of scenario is good for producing thunderstorms and graupel.  The inclement weather should last into Sunday.

Then all eyes will turn (perhaps all eyes have already turned) to the monster of a system being noted on multiple forecast models and in the GEFS.  The GEFS shows about a 30% chance of real winter cold and snow at the end of the month, but the fact that the European model and the deterministic GFS continue to show this feature (and coupled with a strong NAO) gives us a bit more hope than our typical maybe it will snow comment.

Of course, anyone who has seen the new movie "Rogue 1" can't help from having a bit of hope.


Barry Lynn

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