Sep 06 2012

Long range models already hinting at snow before summer ends across the upper midwest.

For those of you who love winter, it may get underway very soon for the upper midwest, according to the latest GFS model. The potential system appears to originate from the Yukon territories and dive southeastward towards the US. However, I do not think it will be cold enough for snow south of I-94, but areas like Grand Forks, Winnipeg, and International Falls could have a very interesting end to summer. Now, this is two weeks out and a lot can happen, and consistency needs to be seen before any possible scenarios are looked at. This does fit the idea that was put here by Weather Advance and other meteorologists that September may be warmer than normal, however, we will probably begin to see a temperature crash as September comes to a close. Even if this does not happen, it is definitely a very ominous sign to be talking about a possibility of snow in September before summer has even ended, and is a sign that the el nino over the central pacific is maturing and will help to lead to a cold winter across areas mainly east of the rockies. Regardless, this is an indication that summer will be coming to an abrupt end as the natural seasonal changes begin to occur, and as that happens, unlike last year, where pressures were low over the US, the pressures will flip over North America, and the US is going to experience higher than normal pressures. The reason for that is the surrounding air masses over the atlantic and pacific will be warm, and that forces pressures to lower over those areas, and stuck in the middle, the US must see an appreciable pressure rise due to this, and as we all know, cold air in the winter is associated with higher pressures simply because cold air is dense and sinks, causing pressures to rise. Interesting times ahead.

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About the author

Eric

Hello, my name is Eric and I have had a strong passion for weather ever since I was very little, and over the last few years I've begun to research and really understand what drives the weather and have began to try my hand at forecasting. I personally love to track winter storms and hurricanes because of all of the uncertainty involved and the major implications that follow with the forecast. I am a very big snow lover and winter is my favorite time of the year, plus it's also hockey season for me (Go Hurricanes!). I really enjoy everyone's forecast and insight, and I enjoy answering questions anyone has about weather or weather related topics.

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Jason

September 6, 2012 at 5:18 pm (UTC -4) Link to this comment

LovE love love it great post
Eric Webb

September 6, 2012 at 11:54 pm (UTC -4) Link to this comment

Thank you Jason. I have huge doubts that this will happen, at least the exact scenario the GFS is showing, but I think a large temperature crash will set in towards the end of September across much of the US, and will lead us into the start of a cooler than normal fall for areas east of the rockies.
Eric Webb

September 7, 2012 at 12:02 am (UTC -4) Link to this comment

The GFS ensemble members and the ECMWF still agree that an interesting feature will be crossing the atlantic, and in about 10 days will be in the vicinity of the Antillies. This will probably be the subject of my next post along with Leslie and our first major hurricane, Michael.
Left

September 7, 2012 at 12:39 pm (UTC -4) Link to this comment

And now it shows a heat wave.
Eric

September 7, 2012 at 11:41 pm (UTC -4) Link to this comment

@Left, I understand the GFS is inconsistent and not all that reliable after a week. However, perhaps you could explain to us why a heat wave would occur towards the end of September given the complete flip in the pattern over North America and the tropical pacific. Look at the pressure falls and rising water temperatures over the central pacific, and with a warm AMO in place that means the pacific and the atlantic will be warm and will have lower than normal pressures. In the middle is North America, which is forced to have higher pressures, and as we know in the fall and winter higher pressures are associated with cold air. How do you get a heat wave out of this set-up? The general pattern supports a significant cool down, especially as the natural seasonal changes begin to occur, and with the natural seasonal changes, the higher pressures currently over North America are associated with warmth due to the longer wavelength radiation in the summer, but once the wavelength shortens as fall begins to come around, the same conditions in place do not result in warmth, but instead colder weather. The longer summer wavelength radiation is why in the summer a -NAO or -AO will not produce the same effects as in the winter, instead the opposite occurs, and the US warms up. This is exactly what is about to occur, and the temperatures over North America, especially over the US will begin to drop and in a very big way. I understand that saying that it may snow over the upper midwest in summer is overdone to some aspects, but such a set-up as we are seeing, the general idea remains the same. Given how dry it has been over the midwest, naturally with overall drier air and drier soil in place, extremes in temperature will not be hard to come by, and given how warm the summer was, it will probably get cold very easily and quickly due to the fact that without water’s high heat content, the atmosphere is very susceptible to rapid changes in temperature.
Jake

September 8, 2012 at 2:04 pm (UTC -4) Link to this comment

I’m up in Grand Forks! I’ll let you know how the weather goes. It’s already a bit chilly but we are loving it Bring on fall and winter!
Eric Webb

September 8, 2012 at 8:51 pm (UTC -4) Link to this comment

@Jake, the forecasts for AO and NAO are leaning towards the negative side as we get beyond the day 10 timeframe. Of course with el nino in place, troughs tend to be stronger in the fall over North America, and also with the natural seasonal variability changing the pattern over North America as we currently have above normal pressures in place thanks to the el nino, and in a summer time pattern higher pressures leads to warmth, because the longer wavelengths of solar radiation. So the compression from the higher pressure leads to warmth like a pressure cooker. However, in winter the sinking air results in cold air due to the shorter wavelength radiation, and as the seasons change, expect the pattern we’re currently in to turn around, and it’s a good bet that we’ll see some ‘initial shocks” before winter gets going.
It is a natural pattern and makes sense that we would see initial cold shots even as early as September because what happens is the amount of sunlight received in the polar regions drops as the summer and fall progress, and naturally less sunlight energy means colder air. Well, as the air cools, the pressures rise. At the same the mid-latitudes are still receiving plenty of sunlight and the amount of cooling isn’t as great, so the pressures drop as the air remains relatively warm. When you get this set-up with high pressures over the arctic and low pressures over the mid-latitudes, that is essentially a negative AO, and we know as weather geeks, that means in the fall and winter that cold weather is coming to the US, at least in most cases. However, when the cold air becomes somewhat depleted over the arctic and the air cools over the mid-latitudes, the exact opposite begins to occur, and after a significant release of cold air from the arctic occurs, the pressures will lower generally over that area and the pressures will rise over the mid-latitudes will rise as the air cools, thus balance is created, and a more positive AO takes shape. At some point though, imbalance will occur because as sunlight energy remains low over the arctic and higher over the mid-latitiudes, thus the pressures will one again rise over the arctic and drop again over the mid-latitudes. This is a generalization of what occurs with AO and NAO, and how it is cyclical, and this is a good reason why the AO or NAO can only stay in one state (negative or positive) for only a limited time, and they will eventually flip.
Left

September 12, 2012 at 2:11 am (UTC -4) Link to this comment

@eric, Yes I was making a point as to the fact that the following run of the GFS showed a great increase in temperature, as is customary of GFS runs at around 180+ hours. Now, I would hardly call it a pattern flip, the pattern now is probably the most unstable pattern you can have as far as the pacific is concerned with this quasi el nino. And you and I both know the AO NAO are impossible to predict beyond a week, a couple days even, last winters holly pattern flip taught us that. Also it’s important to have at least a neutral NAO and AO during the fall because this allows snow pack to build up in Canada. In many years I have found that negative NAO and AO during the fall usually result with positive rebounds in the winter.
Eric

September 12, 2012 at 7:26 pm (UTC -4) Link to this comment

Left, you might want to check out my latest post, I was not crazy after all, and I think you’re about to eat your words. Trying to say it shows a heat wave without providing any evidence to support it given the pattern we are currently seeing is not very wise. No heat wave over the upper midwest at 180 hours, in fact there could be a few rare summer snowflakes as far south as Chicago, and if this occurs it would be a very big forecast win for me.
Eric

September 12, 2012 at 7:30 pm (UTC -4) Link to this comment

I’ve mentioned the potential for summer snow over the upper midwest and upper great lakes region for almost a week, and if I’m right would be a very huge forecast win, predicting a rare summer snowfall 2 weeks in advance? They don’t call this site Weather Advance for nothing. We shall see what happens, but this going to be a very interesting system to track.
Left

September 12, 2012 at 10:59 pm (UTC -4) Link to this comment

The ground temps just aren’t going to be cold enough for snow, the waters of Lake Michigan and Superior are much to warm, and is like a latent heat factory. The northern most tip of Minnesota may get a flake or two, but not much more.
Left

September 12, 2012 at 11:00 pm (UTC -4) Link to this comment

But I do agree that it will be very interesting to track.
Eric

September 13, 2012 at 7:33 am (UTC -4) Link to this comment

Left, here’s what I said about the Great Lakes being too warm on my other blog:”Lake Superior and Lake Michigan will not be giving off too much heat for there to be snow, that’s almost as absurd as saying that they are too warm during the winter to allow temperatures to go below zero. The large scale pattern is about as good as it can get for snow in September, and I provided my reasons above. With the NAO going negative, a large ridge developing over the west, which will force cold air down into the Great Lakes, the system itself will be going through cyclogenesis, and the processes of negative advection, and melting of the snowflakes above the surface will produce a large scale cooling, and it will probably be just enough to produce snow, or at least a rain/snow mix.” I also later said.”…. trying to say that Lake Superior and Lake Michigan are giving off too much heat? Have you even looked at how large this mass of cold air will be, and have you looked at during the winter, how the lakes, don’t give off enough heat to keep the temperatures above zero? To add to that, the processes of negative advection and the initial melting of the snowflakes will only aid in helping to cool the atmosphere surrounding the western side of the low pressure even more.”
The mass of cold air is hundreds of thousands of miles in area from the ground up, thousands of feet above the surface, to hundreds of miles around, versus the lakes Superior and Michigan which have a surface area just over 50,000 miles. The cold airmass is very large in comparison to the Great Lakes, and as we have seen in the past, the Great Lakes do little, if anything to warm the large cold air mass as it passes over the lakes, but we usually get moisture enhancement and plenty of lake effect snow in this set-up, although it is a little early for the lake effect snow season.
Left

September 13, 2012 at 9:37 am (UTC -4) Link to this comment

How is that absurd? During the winter theyre practically frozen over so of course they don’t block cold air. But it’s not winter, in the summer and early fall they retain all the warmth, especially after the Midwests record heat. And the 850 millibar temps arent even that cold, I can’t check the most recent run because I’m on my phone, but if they were forecasted below upper 20s then yes I would agree that the storm could possibly bring in enough of its own cold air that would allow snow to reach the ground. But its just not there. Yes during the winter time this is a perfect set up, but it’s not winter, it is a sure sign of a more progressive pattern which we certainly did not have last year, and the ecmwf showing a low moving up the coast in this time frame is a great sign as well.
Eric

September 13, 2012 at 4:14 pm (UTC -4) Link to this comment

They’re typically frozen over? No, that’s not the case, Erie is the only lake that actually freezes over, and it does not even happen every year. Superior does not freeze over, yet, Northern Michigan and Wisconsin see temperatures well below zero. You don’t seem to understand history and how these situations evolve, just because the lake is warm and gives off heat, that does not mean it is going to significantly modify the cold airmass in place, because other factors are simultaneously working along with the cold air, like negative advection and the melting process of the snowflakes above the surface.You also don’t seem understand that with these systems that undergo rapid cyclogenesis that the atmosphere can be very dynamic, and it does not have to be at freezing for it to snow. The 850 millibar temperatures are forecasted to be anywhere from 0 degrees celsius to -3 celsius, and that gives us a temperature range at that level anywhere from 32-26 degrees, which means that some areas will be below the upper 20s, which means if that’s the case you would agree that snow could reach the ground. Indeed, the models are starting to see the small-scale features that will be at work with this system, and in fact, the latest GFS shows snow accumulations of over 1 inch over north-central Wisconsin (I think that is overdone) and shows significant snowfall north of Duluth, MN of in excess of 2-4 inches, (still seems overdone) but it is a little more reasonable given how much more cold air will be in place over that area. The ECMWF is a little faster and more progressive with the low pressure area and moves it very quickly into Ontario, and shows the frozen precipitation mainly north of I-94 (and the first lake effect snows!).and this agrees with my original ideas on September 6th. Overall, I am leaning towards my original ideas that snow will be mostly confined north of I-94, but given how uncertain the situation appears, and the dynamics involved snow can not be ruled out south of there. Regardless, the main story with this low pressure will be not be the snowfall it may produce, but the severe weather that it produces over the central midwest to mid-atlantic and northeastern states. Hhowever, the fact that we are even talking about the possibility of snow in summer is astounding, and is a statement to the fact that we are seeing the atmospheric and pressure pattern flip that I mentioned would occur due to the el nino, and the pressure rises over the high-latitudes, among other factors, which are also mentioned in the Weather Advance preliminary Winter Forecast.