50/50 chance of waking up to snow tomorrow morning...better chance Thursday morning

The snow forecast starts with the weak system moving down from Canada tonight. Temperatures are marginal for snowfall, so the precipitation may start off as rain, but will change over to snow at some point. The other question is if the precipitation will extend far enough to the south for us to get any. Looking at the current radar...



The precipitation is currently around where anticipated by the forecast models, if not a bit south. These models show the southern portion of the precipitation brushing us late tonight, so I'd say there's about a 50/50 chance of us waking up to some snow tomorrow morning. Admittedly this doesn't look as good as it did last night, but it wasn't going to be that much in the first place, so I wouldn't worry too much...






Looking ahead to the potentially bigger storm on Wednesday Night/Thursday Morning, the overall model trend has been to shift the storm slightly to the west. However, the most reliable forecast model, the ECMWF, keeps the storm in about the same place as it was forecasted to be yesterday. The ECMWF is entering its so called "deadly" range where it locks on to the track of a storm and the track of the storm ends up being very similar to what is forecasted. Therefore, I tend to favor the usage of that model when forecasting what will happen with this storm. Of course, there is some uncertainty as always when forecasting 3 days out and the ECWMF still has a shot at tracking the storm further west during its next two runs. However, I feel it is more likely that the other models adjusted the low too far to the west, and will end up adjusting back to the more easterly track of the ECMWF.

Here's an image of where the ECMWF forecasts the storm to be Thursday Morning:



Squinting, one can see that the low pressure is forecast to be around Buffalo Thursday Morning. Compared with yesterday's position, the track of the ECMWF hasn't changed much at all, and I will therefore stick to my forecast of rain Wednesday Night changing over to snow shortly after midnight before ending shortly after 12 pm on Thursday. As for accumulation amounts, I would expect 2-3" of heavy, wet snow. The main accumulation will be on cold/grassy surfaces, and even on those surfaces the snow won't accumulate right away because of ground temperatures still being above freezing (the delayed accumulation usually happens because of this with every first snowfall). On roadways, I would be surprised to see much more than just slush accumulating. So obviously there will be no snow day with this storm, but it should still offer up the first accumulating snow of the season and make driving a mess Thursday Morning.

Snow Monday Night, then something bigger brewing later in the week?

It is finally time to pay attention to the possibility of accumulating snow in Lake Orion, as we will likely get a quick inch of snow tomorrow night, and a decent shot at getting our first notable accumulation of the 2009-10 snow season with a storm system later in the week.

First, I'd like to give a quick mention to a system tomorrow night that will move through and more than likely give us our first measurable snowfall of the year. It's not going to be anything too big - just a quick half inch or inch of snow ending by sunrise Tuesday morning - but it's still worth mentioning as it will be the first measurable snow of the season.





More notable is going to be a system that will affect us late Wednesday Night and through the day on Thursday. There is fairly good consistency among the different forecast models w/ regards to the track of this system, considering that it is still 4 days away.

Take a look at the forecasted position of this system Thursday Morning from 4 different forecast models (from top to bottom, the GFS, ECMWF, GGEM, and UKMET). They all support a track along or just west of the spine of the Appalachian Mountains. Personally, I prefer a track just west of the spine as I think it would be unreasonable to expect the northern stream trough to phase (combine with) the upper level low in the Southern U.S. so late that the track would be up the spine of the Appalachians. (More on this subject two paragraphs down)









Considering a track just west of the spine of the Appalachians, I would say it is fairly reasonable to expect that we will get some accumulating snow on Thursday. The projected track is a pretty good winter storm track for our area, but the cold air does not look to be in place until after the precipitation starts. Therefore I would say it's reasonable to expect precipitation starting as a cold rain on Wednesday Night before turning over to snow Thursday Morning and dropping a small to moderate amount of accumulation before departing the area Thursday Afternoon.

This is a fairly advanced subject that is more than what is usually covered on the evening news, but I figure it's in my best interest to point it out anyways, so I will say that one thing to note that could potentially change the track is that there is a "northern stream" trough that will phase (combine with) an upper low pressure system across the Southern U.S., giving us our storm system. Currently, this is not expected to happen until Wednesday Night. However, if this phasing happened earlier, it would also happen further west, and the storm system would thusly track further west, which would likely give us more rain, with a later changeover to snow, and therefore less snow accumulation. If it does appear that the systems will phase together earlier, I will mention it in a future post and adjust my forecast as such.

However, the bottom line is that I currently expect a few inches of accumulation with this system. It doesn't have a very good shot at giving us a snow day, but it has a decent shot at being our first notable accumulation of the season.