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...

Late Tuesday to Wednesday Ontario Storm Impact

Another system will be pushing into S. Ontario Tuesday night and will impact the Wednesday morning commute for many folks.

More models are now consistently showing a possible extended period of FZRA for the Orangeville/Barrie/Peterborough regions Tuesday night and into the Ottawa Valley during the Wednesday morning commute, with a few mm of ice accretion possible at this time. However, precipitation will first begin as snow Tuesday overnight in Ottawa, with the change over to freezing rain/ice pellets occurring between 7-8am. I'm seeing the potential for a quick 5-10 cm of snow to fall early on Wednesday, so be prepared and give yourselves some extra time when travelling Wednesday morning. The forecast sounding below is for the Ottawa Valley region valid for 7am Wednesday.

The deformation zone is looking to sit through the Wawa area and up through Northeastern Ontario, which will keep the heavier snow to the north of it. Amounts of 10-15 cm are expected for many of  the locals north of the deformation zone.

Friday-Saturday Eastern Canada Storms

The initial low pressure area will push into the Great Lakes region Friday and Friday night. This will initially bring some light snow or mix to parts of southern Ontario Friday which will likely change over to light rain from Toronto on southwest early Friday night, as the system kicks out any lingering cold air. Areas from Barrie to Peterborough to Ottawa on north should stay all snow with a few cm's possible by Friday night. The exception looks to be areas south of Ottawa to Kingston and areas north of lake Ontario where freezing rain or ice pellets is possible. I am also concerned about some mixed precipitation lingering into the early night over parts of southern Ontario with some pockets of low-level cold.

Farther west, confidence is higher for a significant snowfall, north of the primary low over northern Ontario and western Quebec.

Since the energy looks to remain split, the St. Lawrence River Valley looks to end up getting caught in between the two storms, which would put them in a more subsidence zone, resulting in lighter snowfall.

If the energy was to phase, then the coastal storm would end up stronger, would move slower and would get drawn farther north, resulting in higher snowfall across central and northern New Brunswick and PEI. However, the latest models have been shifting away from this scenario.

On the other hand, the shift in the track will send the heavier snowfall slightly farther south and across a large portion of Nova Scotia and southern New Brunswick. Some pockets may see a bit more than 30 cm, but generally the area should end up with 15-30 cm, as the storm moves along and does not stall. As for the Halifax, NS area I am currently expecting around 15 cm of snowfall accumulation at this time. 

Rain with some mixing may be possible along the south coast of Nova Scotia and temperatures may end up staying too warm for any falling snow to accumulate over the extreme southern tip of Nova Scotia. A slight shift in the track is all that is needed to change the precipitation type and amounts.

Behind the primary low there will be lake-effect snow east of the Great Lakes Saturday into Saturday night, before another clipper storm dives in from the west on Sunday followed by the arrival of the next Arctic blast early next week.

Messy Weekend Storm Jan. 9-11, 2016

A few systems will come into play this weekend for parts of Eastern Canada and will make their way into Atlantic Canada at the start of next week.

As the main system comes in late Friday, I expect mainly snow for Central Ontario with mixing through Cottage country and rain for Southwestern Ontario. Some freezing rain / ice pellets will be possible at the onset of precipitation from Dufferin / Barrie, along and North of the Hwy. 7 corridor, and South of Algonquin. I would also like to point out the potential for some freezing drizzle over Southern parts of the Ottawa Valley at the end of Friday. 

Saturday should see rain across Southern Ontario with some mixing through the Nickel Belt and snow for Northern Ontario. Along the warm front through Southeastern Ontario and the ON/QB border some freezing rain is possible Saturday morning and early afternoon before changing to rain as temperatures continue to slowly rise.

By Sunday I am looking at rain gradually changing to a rain-snow mix and eventually transitioning to snow for most of Ontario and Southern Quebec as the cold arctic air filters South. Another period of lake-effect snow is possible on Monday, as snow squalls develop East of the Great Lakes. Atlantic Canada will see rain for the most part late Sunday into Monday. Parts of New Brunswick may see a brief occurrence of freezing rain / ice pellets late Sunday, before changing over to rain.