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!

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!

Late Season Snow Storm Tonight!

A late season snow storm is in store for the area tonight as low pressure moves to our south along a stalled frontal boundary. As this low moves along the front, cold air from Canada will advance south. Meanwhile, the low will throw moisture up into the cold air.



The precipitation will likely start as some rain later this afternoon and tonight. As that cold air moves in, however, it will change the rain to snow overnight. As is often the case with storms at the beginning and end of winter, the higher elevations will end up with more snow than the valleys. The models haven't been doing a good job with this storm so far; just yesterday they had us getting barely anything. However, they seem to be in better agreement with this morning's runs, and looking at the radars to our west, I think we are in for a decent snow. The map below is a little confusing since its hard to incorporate the elevation factor into the map. For downtown Groton, I would say 3 or 4 inches will fall. In the hills surrounding Groton, more like 5 or 6 inches. I think the highest amounts will be in the hills north, east and south of Cortland, especially down towards Binghamton. I wouldn't be surprised to see someone down there get 8-10", maybe even a foot!

What happened...or rather, why it didn't

I've done some thinking and analyzing this morning, and I think I know where I went wrong with my forecasts last night. Lets start by looking at the last radar image I posted.



As you can see by the radar loop from last night, the snow developed mostly over Western Pennsylvania, West Virgina, and Eastern Kentucky, with lake snows further northwest over Ohio, Indiana and Illinois. Now we did and are still getting the lake enhanced snow, but the other area of snow never formed. Why? The answer lies in the two images I made below:





The area where the snow broke out was just west of and along the spine of the Appalachian mountains. These mountains acted as a lifting mechanism. As the winds hit the mountains, they had no where to go but up. Rising air cools, and with all the moisture left over from the storm, condensed into clouds and moderate to heavy snow. This is called upslope snow. Since there is not nearly the elevation gradient over our area as there is to the south, there was not enough lift to cause a secondary outbreak outside of the light lake effect. This just goes to show that there are so many factors that go into forecasting, which is why it is such a tough job.

And just in case you were wondering how much snow fell as a result of the upslope effect last night in the mountains, Accuweather.com meteorologist Jesse Ferrell put together a small list of some totals on his blog, which you can see here.

One other note about this storm. I have had over 800 hits on my website since Monday, including 571 yesterday! I just wanted to thank all of you for using my site and making it well worth my time. I really enjoy this and I am so happy that you are finding it useful! Thank you again!

Now, one final thing for now. For the past month or so, I have been working on a new website with a group of meteorology students here at SUNY Oswego. This site will give weather forecasts in a similar format to grotonweather.com for clusters of 2-5 counties. This will be a great source for specific weather information outside of our area. I am both the chief meteorologist of this new site, along with the forecaster for the Finger Lakes region. I have set this site up so that Tompkins, Cortland and Southern Cayuga are in a cluster. What does this mean for the future of grotonweather.com? No changes! I simply using grotonweather.com for that region, keeping everything the same for you. This new site will be launching this weekend and will have the URL www.empirestateweather.com, so check it out come Saturday!