Monday, February 11, 2008

Good news: A shot at winter weather; bad news .... would be ice if we get it.

An interesting setup being depicted by the last two runs of the GFS model -- this is what is a called a "Miller B' system -- low pressure forms over the western Gulf coast or southern Mississippi valley, tracks northeast toward or even west of the Appalachians, then the low "jumps" east and reforms off the N.C. coast.

As you can see by the following three maps of the 18z run of the GFS, a cold-air damming situation occurs late Saturday into Sunday.

Here is the wee hours Sunday morning. You can see precip moving in. Note the strong (1033 mb) high pressure system parked over New England, pumping in cold, dry air.
Now for dawn on Sunday. The high is still over Maine (although slightly weaker at 1030 mb) and precip is flooding the area, even as the shallow layer of cold air is pumped in from the north.
And early Sunday afternoon. You can still see the CAD "signature" although it has retreated to the north.

Still, computer models are notorious for UNDERforecasting the strength of cold air damming events, so we'll have to see.

Bottom line -- still in the 5-6 day range -- far too soon to even attach probabilities to this. And to be sure, ice storms are events to root AGAINST, not for. But mainly, this is a reminder that we are still well within the window of time when winter events are possible.

Another note -- a few more frames ahead and you would see the low jump off the coast, then a big shot of arctic air will plunge southeast early next week. There are some hints we might see a system during that time, but that's all we have are hints right now.

Stay tuned.


Anonymous said...

I keep checking for an update...what's the latest??

Anonymous said...

the update is...its gonna rain.