Tuesday, October 28, 2008

Nor' Easter, then Lake Effect

Our nor' easter is starting to really wind up off of the New Jersey coast this morning. This has spread a solid area of precipitation from the Finger Lakes, east. Most of what you see on the radar is rain, but it has already changed over to snow in Binghamton and Scranton.

At 9AM, it was 37 in Ithaca, so that, combined with where it is already snowing in Binghamton, has made me expect a change over to snow a bit earlier than I was anticipating last night. This has been reflected in the higher snow amounts on the snow map below. For Groton specifically, since I placed us on the boundary between two areas, I would expect to see 2 or 3, maybe 4 inches downtown, with as much as 5 or 6 on the hills.

This storm should be well on its way out by midnight tonight. However, just as that storm departs, the Lake Effect machine will kick in for Wednesday and Wednesday night before tapering off Thursday. It is still too early to tell where exactly the heaviest lake effect will set up, and whether or not it will remain snow, but here is my best guess for snow intensity at this time:

If you want to help me out with this, as I sit up here in Oswego, it is very hard for me to know what exactly the precipiation type is elsewhere. It would be very helpful if you could leave a comment on here letting me know when you first see snow, no matter where you are. Current data from spotters is very imporatant to meteorologists, so I would really appreciate your observations! Thanks!

Monday, October 27, 2008

First snow of the season!

The past 24 hours have been crazy on the weather models. Yesterday, all but one model, the North American Mesoscale (NAM) were showing an area of low pressure heading into eastern New England, leaving Central New York more or less alone, with lake effect kicking in towards Tuesday night and Wednesday. The NAM, however, brought the storm much closer, giving our area its first accumulating snow of the year. Over the past 24 hours, however, the other models have come into agreement with the NAM, and suddenly we have a snow storm on our hands!

Now, keep in mind, I use 'snow storm' in the context of a normal October. We won't be seeing feet of snow, but for a first snow, this is pretty big. Here is what is happening:

An area of low pressure is beginning to form over North Carolina. Already moisture is spreading northward ahead of this, though most isn't reaching the ground yet. As this storm explodes and heads north, it will pull down some chilly air. That will make the precipitation that starts tonight and for the first part of tomorrow mostly rain. More importantly, however is that this rain will be snow not very high up in the atmosphere. As it melts, it will aid in cooling things down and changing precipitation over to snow. The higher elevations will see the change over first, probably as early as mid to late morning tomorrow. The lower elevations will begin to change over during the afternoon and evening hours. By tomorrow night, everyone should be seeing accumulating snow. Cayuga and Tompkins counties are not under any advisories, but Cortland county, with its higher hill tops, is under a Winter Weather Advisory.

The winds will be gusty with this as well. That, plus the heavy, wet nature of this snow could cause some branches to come down in the higher terrain. Had this come a week or two earlier, when the leaves were still on the trees, we would have some problems. We are lucky though and I am not anticipating many, if any, power outages.

This storm will be a quick mover, so real high totals aren't expected. The map below shows what to expect through 9AM Wednesday. Beyond that, Lake Effect snows will set up, but probably stay to our north, with additional accumulations. Stay tuned!