New Year's Eve cooldown on the way
Saturday, December 28, 2013, 9:53 PM -
New Year’s Eve is fast approaching and many of you are finalizing plans so here’s a look at what kind of weather you can expect across the country that evening.
The first thing that stands out in the long range forecast models is positioning of the polar vortex that will be centered in west-central Québec along the eastern shoreline of Hudson Bay as shown below.
So what does that mean? This feature is quite significant because it will dictate what the surface temperatures will be that evening. As Canadians, most of us know by now that the words “polar vortex” can only mean one thing: frigid Arctic air.
The image below shows an ensemble mean forecast of the temperature departure from normal, or in other words, where above, below, and seasonal temperatures will approximately be for the period of December 30th to January 4th.
Across much of the Prairies and eastern Canada, temperatures will be below seasonal with the real core of the Arctic air over central to northern Ontario, Québec, The Maritimes, and Labrador. These regions look to be anywhere from 11 to 18 degrees below seasonal. Newfoundland, southern Ontario, and western Saskatchewan look be around 5 to 10 degrees below seasonal.
Referring back to the very first image, a ridge is observed in western Canada with the ridge centered along the British Columbia coastline. This translates to temperatures for British Columbia being near seasonal to slightly above for coastal regions. The trend for Alberta and the B.C. interior is a little deceiving here as the image above would indicate above seasonal temperatures. The reason for the trend to show temperatures above seasonal is the milder air will push in through early January as the upper ridge pushes east ushering in milder Pacific air mass New Year’s Day through January 4th.
Since the image above is the average through to January 4th, the numbers have been skewed to the above seasonal end. Below, the image shows the Canadian model temperature forecast for New Year’s Eve illustrating lows of -12ºC to -20ºC for the Foothills and southwestern Alberta. Central to northern Alberta looks to be near the -20ºC to -30ºC and some areas could even be a little colder. Interior B.C. looks to be around the -5ºC to -10ºC range.
In terms of precipitation, the pattern is relatively quiet with a few disturbances across the country. The Atlantic Provinces looks to have some flurry activity from a surface trough as well as some sea effect snow. Mainly coastal regions will see the bulk of the flurry activity. The Eastern Townships and the Saint Lawrence Valley also look to be under the influence of a weak trough, thus flurry activity seems possible here. The influx of Arctic air into the Great Lakes should set up some lake effect snow but we are a little uncertain if it will be a significant event or just some light snow, so this could be something to watch for in the Snow Belt regions of Ontario. There is also a developing low pressure system across the Mid-Western U.S. that is forecast to push into southern Ontario New Year’s Day so we need to keep watching this system as well.
Across the Prairies, it will be relatively quiet with a departing clipper for Alberta. Flurries are likely across western Saskatchewan and for Alberta with steadier, but light snow for the Foothills along the stationary Arctic front. Southern and coastal British Columbia look to have a weak trough ahead of the next Pacific low thus there is the risk for patchy showers with mixing at higher elevations as seen in the image below.
Our forecasts are updated on a regular basis so be sure to check your city page for the latest forecast information for New Year’s Eve.