If you look out your window today, cold and snowy like the middle of winter, you would probably say, of course it will be a white Christmas. However, for parts of Southern Ontario, Mother Nature might say; “oh yeah, hold my beer and watch this…”
There are a couple waves of moisture (Dec.17 – 18th, Dec. 19-20nd, Dec.21 – 23rd December 24th – 26th) appearing on some of the models that have the potential to bring either more snow, or a Grinchy green Christmas to parts of Southern Ontario. From areas just south of the GTA down towards Hamilton/Niagara over to London and south to Windsor have the highest chance at potentially losing the snow they have on the ground. Regions to the north and east of that will likely be fine, but could also see more snow added or some messy mixtures.
The Main Threats
In my last white Christmas blog post I discussed the potential of a relax in the amplified cold and dry pattern over Ontario and Quebec. The relax does look to occur somewhere from around Dec.18th to Dec.26th with a few short returns to an amplified pattern in between. During that time, storms will fluctuate between Alberta Clippers that move from the north west across Canada and the potential for a couple storms from Colorado and Texas. Storms from that region could also combine with some clippers or strengthen over Ontario as today’s storm did. As these storms approach Ontario, there is some cold upper level blocking over Northern Ontario and Northern Quebec that should help keep the storms from continuing to travel north and west but rather move zonal, west to east across Ontario. A little bit of SE ridge in the U.S. will also help to push these storms north, then east.
The main factors to consider with this relaxed pattern;
- How strong will the amplified pattern be during this time? Will it be stronger and bring more cold with light clippers and force the major storms south?
- How strong will the SE ridge become? Will it grow too large and force storms further west?
- Or will it stay just the right size to bring successful snow storms to our region?
These are the questions the long range models are trying to work out.
Here is a brief discussion on a couple potential storms; remember the actual systems could vary widely from the below, or not even occur. This is just a discussion of the options appearing on the last couple model runs:
There are actually a couple clippers showing up during this time. Most of them look rather weak and effecting various regions, mostly central Ontario on the last couple model runs. There will also be some Lake Effect snow in the usual spot as these clippers move through, so expect more snow in those regions
During this time frame, especially towards Dec.18 to 20th there could be some warm ups with clippers as the temperature moderate with relaxing amplified pattern cutting down some of the true arctic air.
It is possible that some mixing occurs around Lake Huron, Lake Ontario and Lake Erie depending on the actual track.
As it stands currently I don’t see many of these clippers strengthening into anything significant (beyond 10 cm) but I will keep watching them.
Dec.21 – 26th
This time frame looks very interesting for significant storms, but also holds the potential to wipe out snow cover right before Christmas. I call these storms; the Grinch storms…
Recent model runs suggest the SE Ridge flexes it’s muscle during this time along with storms originating from Colorado and Texas. Storms from this region often become rather major for Ontario and Quebec. However the saving grace this time might be how strong the high pressure blocking and amplified pattern remains over Northern Ontario and Northern Quebec. Without this ingredient, these storms could have cut west as GLC and really made a mess. With the blocking to the north and the SE ridge to the south, the storms will likely cut straight through southern Ontario into Quebec, or remain south of Ontario and miss us depending on the strength of the colder amplified pattern.
This will be key to work out over the next 5 to 8 days. The models will likely flip flop with this solution right to the middle of next week.
You will want to keep an eye on our page for updates on this system and its impacts (remember, if any). By the way, these type of storms and the pattern are common in La Nina winters, and what you might expect to increase snow totals.
The Grinch storm will just depend on how large his heart grows that day…
The Week 3 forecast
With any of the above potential storms discussed there appears to be the chance of some mixed precipitation in some areas as the upper level air temps and location of the low might not support all snow in a relaxing of the pattern scenario. However, that doesn’t mean that local cold air damning (CAD) or low level cold couldn’t support snow, sleet or freezing rain in certain areas.
The period from Dec. 21st to the 25th will have to be watched closely to see what occurs. No matter what, it should be an interesting time to storm watch 🙂
Here is the week 3 forecast. I’ve added more certainty for some areas to maintain snow cover , but SW Ontario, including the GTA remains the most uncertain:
Just for fun, here is the latest CFS for snow cover across Canada on the morning of Dec.25th:
We wont have more certainty until the Euro comes into range this weekend. Looks like we wait until the week 4 Dec. 19th to 21st to frame to be certain.
Mother Nature always likes to keep us guessing…take it away boys…https://youtu.be/_SGlPnA_iCk