No New Post Tonight

New post will for sure be up by noon tomorrow...just don't feel like writing this when I'm tired it wouldn't be very good.

Quick Post...in between events

Well nothing interesting is happening w/ regards to snow right now, and nothing interesting will happen until Wednesday, so just a quick post tonight.

Monday a weak system is still expected to move through. We'll get some snow out of the system, anywhere from 1-2" looks to be a decent bet.

The possible big storm will occur on Wednesday. A strong low pressure system will eject out of the Rockies, zipping quickly off to the ENE. I'm going to be perfectly honest that right now, the models have SE Michigan in a pretty good spot with this system. That's great, but when is the last time you've heard of a forecast staying exactly the same through five days? I'm at least partially excited about this upcoming storm, but I'm going to hold off on hyping it at all for a day or two. For now I'll just put it out there that there is a chance of significant snowfall on Wednesday, if everything works out correctly.

Check back here tomorrow night for a longer post featuring more details of the Wednesday system, as I will be able to state where it will track with a greater certainty, allowing me to discuss realistic snowfall possibilites for our area based on what I feel the track will be.

For now, I'll set the snow day grade for the Wednesday system to a C, simply because we're the frontrunners for receiving a potentially significant snowstorm in 5 days. Specific details obviously can/will change, and as they do, I'll adjust the grade up/down accordingly as we get closer to the event.

First Real Snow of the Season...Yes it's actually gonna happen this time

Yes, we are actually going to get our first real snow of the season tonight. As I said yesterday, this is a nearly perfect setup for lake effect snow for our area (still doesn't mean we're going to get much) and with an upper low moving through the area to help things out, there is an extremely high chance of lake effect snow showers moving through our area overnight.

Let's take a look at the current radar:

The band stretching roughly along and south of the I-96 has been propogating eastward in from Lake Michigan over the last few hours. This trend is expected to continue overnight, with the band moving through our area around midnight. Snowfall could actually be rather heavy at times with this band, but it will not be a long duration event, so I expect accumulations to be limited to around an inch.

Snow will also fall occasionally tomorrow. It will continue to be rather heavy at times when it does fall, and in the heaviest showers, some minor accumulations could occur.

Looking ahead to the longer range, a weak storm system could move through on Monday with some more minor accumulations. In addition, a stronger storm could move through in the middle of next week, but the models are all over the place with where it's supposed to track, so I'll hold off on talking about that one in detail. Most likely someone will get their first winter storm of the season, but it's anyone's guess who that will be at this point.

Nothing good coming out of this storm...but after?

There is no need to cover the ongoing storm for more than a paragraph, as I already called it a "bust" yesterday and explained why it was a bust, so if that's what you're looking for, scroll down to yesterday's post. Sadly enough, the rain that is currently occurring is the storm that was previously forecast to give us a couple of inches of snow. Obviously...that isn't happening as the cold air just isn't going to come in fast enough to give us anything more than a half inch of snow by the time it departs.

Fortunately for people who have been eagerly anticipating a coating of snow on the ground, a better possibility awaits after this storm exits the area. In its wake, cold air will arrive in earnest, with temperatures falling below freezing tomorrow night. This, combined with a strong westerly flow, will serve to allow for the formation of lake effect snow off of Lake Michigan. For those who don't know, our location isn't in a good spot to receive much lake effect snow, but tomorrow night is a setup we can work with. Snow showers will become likely during the early morning hours on Friday with accumulations of up to an inch possible.

The snow day grade with any of the above mentioned events remains at an E.

First "Bust" of the Season and Lessons Learned

Only one subject to cover tonight, and that is the Wednesday Night/Thursday Morning storm, which is rapidly becoming an early disappointment. While the forecast models, if anything, have shifted a bit to the east from yesterday, two other overriding factors lead me to tone down the accumulation forecast. The first factor is that the cold air just isn't going to come in quickly enough for any significant snow to fall. Obviously, it's early in the meteorological winter so cold air will usually be a problem, but I admit that I never expected it to be this much of a problem. The other factor is that surface observations support the low to track a bit further to the west of where it is being forecasted by the models. This as well does not help snow accumulations. Therefore, I am toning down forecasted accumulations with this storm to around 1".

Obviously, this is disappointing, but the weather is inherently unpredictable and it's a given that most forecasts will have to be adjusted as we get closer to the event. If one looks back through earlier blog entries, one will find many other times when my original accumulation forecast had to be adjusted up or down as the event drew closer (although somehow...only the downward adjustments seem to get noticed :P).

Still, there are lessons to be learned from every busted forecast, and here are the ones I offer up:

1) Expect the westward shift to be present again this winter. A theme of the last few winters has been forecast models ejecting an upper low out of the southwest too quickly, resulting in an original storm track of further east than what actually happens. Based on this storm, that trend may be occurring again this winter and I will have to watch out for that and take that into account when forecasting 3-7 days out.

2) Forecast models usually overdo cold air, especially early in the season. Somehow, cold air always ends up being one of the main problems for almost all winter storms, especially early in the season. Yet forecast models usually don't see this problem until 2-3 days before the storm. After a long break from forecasting, I admittedly underestimated the cold air problem and hope to better account for the cold air problem in future forecasts.

So although this storm won't have much to offer up in the way of snow, it offers me a chance to learn from my mistakes and improve my forecasting as the season goes on. And I would still look for snow to be falling Thursday morning, just not as much as previously expected.

Finally, I would like to close by offering up a new "grading system" of snow day probabilities for Lake Orion. I will still be doing yes/no predictions the night before any significant storm, but for the medium/long range I will offer a quick look at the possibilities of a snow day with a grading scale.

This idea was proposed to me by Vinnie Warren, and I thank him for suggesting it, as it is a good idea.

A = Lock it in, snow day has a great shot at happening
B = Above average chance for a snow day, but there's still things that could go wrong
C = Average chance for a snow day, things could break either way as the storm draws closer
D = Below average chance for a snow day, but it's not impossible
E = Forget about it, move on to the next storm if you only read this for snow day chances

For the Thursday Morning Storm, the current snow day grade is an E.

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.