If you live in Ottawa, Eastern Ontario or Montreal, both of which got maybe 3 – 8 cm of snow from this storm, you might ask what happened…where was all the snow?  How can weather forecasters get this so wrong…Well in the weather community we call this one a bit of a”bust”.

Just about every single long and short range model got this one wrong.  The Euro model which is usually king, has been off most of the season, and got this one wrong. The last 2 runs of the Euro did come closer with around 8 cms for the eastern Ontario region.  The GEM/CMC Canadian model, the model Environment Canada mostly relies on, got this very wrong (they had near 15 cm for most of Eastern Ontario).  The GFS came pretty close (which The Weather Network seems to rely on), but was still off (they had 5 – 10 cm for most of Eastern Ontario).  I was also wrong with a prediction of 10 – 12 cm for areas from Ottawa and east to Montreal where I was also quite off.  The areas west Ottawa towards central Ontario down to Belleville I got pretty close with 5 – 10 cm prediction.  I personally recorded 7 cms west of Ottawa.  Even the short range models, which come out just hours before the storm and are usually quite accurate, were off.  Only one short range model that came out on Monday morning was pretty close. The NAM 4K was pretty accurate; here is the image they had predicted (in inches):16231248_10210786700256089_943759438_o

The dissection

There were a couple factors that made this storm hard to forecast;

1) The storm set up was complicated, typically a Low Pressure center off the US East coast cannot throw that much moisture into our area.

2) There was not a lot of cold air to work with, the storm had to generate it’s own, and that did not happen as much.

3) The Low Pressure system was not as strong as the models predicted, which in turn made point #2 a possibility

4) Because of the less amount of cold air in the upper atmosphere for a longer period of time ahead of the storm it started in most areas with a couple hours of freezing rain (with a warm layer above the cold) and ice pellets.  This limited the amount of snowfall, probably in the 2 – 4 cm range.  The models some time have trouble differentiating between freezing rain and snow.

5) The models just couldn’t get the dynamics right – part of the main system moisture broke off to the west of Ottawa up through central Ontario up the valley into Quebec.  This left the area to the east with lighter snow and a dry slot to make its way into the middle of the storm.

Sometime when there is so much disparity among the different models, relying on one particular favourite model can spell disaster in your forecast.

So while we all try to get it right, sometime it just doesn’t happen, even the professionals can’t get it right.  If they could and could read mother nature better, there wouldn’t be some much interest and discussion about weather 😊  Still it was amazing that we pulled off some snow in this warm pattern.

Look ahead

A weak system is sweeping across central and southern Ontario tomorrow night into Thursday.  I don’t expect much from this small system, maybe 5 cm around central Ontario, and west of Ottawa.  Parts around the north shore of lake Ontario including the GTA could expect some rain showers with this system as again little cold air will be available.

After that, come Friday, the thaw pattern finally comes to an end and we switch back to a more typical arctic January pattern.  Temperatures will much colder this weekend and closer to normal.  Watch for lake effect snow to start back up south and east of the Great Lakes come late Friday into Sunday.  Once again many areas will be measuring snow by the foot!

February is looking colder and more typical of a winter pattern.  Watch for smaller Alberta Clipper storms to come through starting early next week.

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