Now that it is finally snowing in Ottawa again. I had some thoughts as to why the models got the track wrong for this storm (it's farther north than predicted yesterday).
This time of year as the sun is getting higher in the sky and the nights are shorter, it is a lot tougher to maintain cold enough temperatures for snow, especially without much snowcover. A brief physics lesson for you.
There is a common misperception that convection (ie hot air rising) is the primary method for the cooling that happens at night. However that isn't the case though convection does play a part. Radiative cooling provides the majority mechanism for cooling. This is essentially infrared radiation (aka IR, long wave radiation, LWR) going out into space. You can tell this is the case where one can see that cloudy nights do not cool off as much as clear nights. The clouds provide an isolative barrier for IR. Now much of the IR comes from the ground. When there is snowcover, there is two reasons that it helps keep things cool, one in daytime and one at night. First snow has one of the highest albedo properties, the ability to reflect rather than absorb incoming sunlight (Shortwave radiation, SWR). Secondly, snow, especially deep snow, provides an insolative barrier from the thermal energy in the ground. The atmosphere cools a lot quicker than the ground does.
So this time of year, the nights are shorter so there is less time for radiative cooling. The sun is higher in the sky and days are longer, so there is more energy being added to the environment. Now combine this with a lack of snowcover that we have, especially to our south from whence storm systems come, it is tough to keep it cool enough to snow.
Now as a result of the winter we have had, the water temperatures of the Great Lakes are near or at record highs. Most computer models don't have the resolution to use the surface temperature data of the lakes as an input. However, I think that with these relatively high temperatures are adding thermal energy as well as moisture to the systems, deviating them from the expected track.
Might be an interesting case study for some climate guy.