Wednesday, December 17, 2008

12/17 - 8pm - White Christmas?

We barely got above freezing today, and that happened in the wee hours of this morning! Things stayed quite cold with dreary cloud cover. Expect some fog tonight and into tomorrow morning. We should top 40 tomorrow and soar to near 60 on Friday!

By Friday, we'll see a storm system come through with a considerable amount of rain. That should exit the area by Friday night. As yet another low pressure system makes its way through north of the area, we'll see more rain for Saturday evening and into Sunday.

That system over the weekend will usher in some very cold air... you know where this is going... and could make way for a snowstorm on Christmas Eve. You may say, "but Ryan you messed up yesterday's snow prediction, how the heck can you expect to forecast snow this far out!?" The answer to that lies in the size of the storm. Yesterday's area of snow was only 20-30 miles wide, and went south of us at the very last minute. This storm will be a monster in comparison, so more areas are likely to get snow, meaning a decrease in forecasting error as well.

The 18z GFS gave us a rain event, but the 12z and the 6z all agreed that this would be a snow-centered storm. The NWS is already calling for snow in their 7-day forecast, so that gives me a little more confidence. The 18z worried me about this being a "Great Lakes Cutter," meaning a storm where the low cuts north to the Great Lakes and keeps snow west of the area. But if I recall correctly, the 18z runs have not been reliable this season, especially for yesterday's storm. So I think we can throw out that model run unless that low track comes up on the oz tonight.

In any case, we haven't had a Christmas with decent snow on the ground since 2004. If we can stay the course with a low pressure track south of us, I think we're in good shape. At this point, I'll call this a chance for snow and nothing else. I don't want to call this one too early... a busted Christmas snowstorm forecast would cause an angry mob (the city of Louisville) to come after me!

1 comment:

Anonymous said...

Looks like a double-low set up. The leading low goes north and west. I think one model had it right on top of us. Either way that is a rian set up. The second or trailing low may have some potential. Moreso a night of the 23rd/Christmas Eve morning event. The 6z GFS looked promising for at least 3". The EURO is not too thrilled about snow potential. It is usually the better model this far out. We'll see.