Will Spring finally make its debut in Eastern Ontario?

Most of us have gotten quite familiar with this upper-level pattern over Eastern Canada for the past few weeks. The relentless surge of cold air from the North broke previous cold temperature records in Southern Ontario last week. On the other hand, our friends in the West have been breaking daytime high temperatures, some of which were above 20 degrees C.

Courtesy Meteocentre

Good news is, the upper-level flow or jet stream as we say, will begin to change and will bring about milder spring-like temperatures over the course of this week. A slack in the upper-level flow will result in a more zonal flow (West to East flow), causing the cold air to remain over Northern Canada.

Near the end of the week, a ridge will develop over Eastern Canada and with it will come plenty of sunshine and milder temperatures.

Below is the the GFS and Canadian GEM Global models showing the amplified upper-level pattern over Eastern Canada for Friday April 15th. You'll notice that it's the flip opposite to what we've been dealing with over the past week. This also means cooler temperatures for folks in the West due to a trough, who have been recently basking in the sun and enjoying the warmth over the course of last week.

So of course now we ask ourselves: How warm will the temperatures be in Eastern Ontario? These are the projected temperatures for the city of Ottawa, and you'll notice the spikes in the daytime high temperatures by this weekend. Once again I'm only looking at two models here, the GFS and the Canadian GEM Global, so there will still be some variability in temperatures before we reach the weekend.

The Weather Network's forecast for Ottawa, Ontario is also on board and calls for plenty of sunshine and warm temperatures for the second half of the week. So go out and enjoy!

-------------------------------- Update April 13, 2016 ---------------------------

All this talk about an Omega Block taking shape at the end of the week is big news for everyone who has been recently hiding inside from the cold temperatures in Southern Ontario. Below is the upper- level flow this weekend, and a typical Omega Block setup with a large ridge of high pressure in the middle surrounded by areas of low pressure in the troughs located on either side. 

Once again this is The Weather Network's outlook for Ottawa, Ontario, and the rest of the week looks  fabulous. So for those who love plenty of sunshine and warm temperatures, enjoy it while it lasts!

Ontario Winter Storm: March 01-02, 2016

Another storm is already on the doorsteps of S. Ontario and will arrive in E. Ontario later tonight. Much of Southern and Eastern ON will see snow with this system, except for a few spots near Lake Ontario and Lake Erie which will see snow change over to ice pellets and even freezing rain . This line will stretch from Windsor to Hamilton and up towards the Kingston area. This will reduce the limit for the amount of snowfall these areas will see.

The areas north of Toronto towards the Ottawa Valley, could see a swath of 15-25 cm of snow by Wednesday afternoon. Local amounts of 30 cm are possible northeast of the Ottawa Valley towards Quebec City. Heaviest snowfall rates of between 2-4 cm/hr will be possible later tonight north of Toronto towards Barrie. In E. Ontario the heaviest snowfall will occur very early Wednesday morning and into the morning commute, as the deformation zone shifts Northeast.

There is still some uncertainty with the storm track at time. Another factor with this storm is its track speed (refer to the 700 mb image). This is a steady and quick tracking storm, so the duration of the heaviest snowfall will be limited as well. This will also mean driving conditions tonight and into Wednesday will deteriorate quickly in combination with strong bursts of snow and strong winds creating near zero visibility.

To end this on an interesting note, while looking at the model soundings, I noticed descent lapse rate values between 3-6 km over S. Ontario. This along with the presence of strong forcing could lead to some thundersnow. The first NAM sounding represents a location just north of Toronto at 10 pm tonight and the second is near Ottawa at 1 am Wednesday.

So don't complain about the snow, enjoy it...