As we know, the strong polar vortex that would typically be located over northern Canada during this time of the year, has come much further south during this week. The center of this upper-level disturbance dropped southward over Manitoba a few days ago before moving into the northwest Midwest of the U.S., and then across far southern Ontario and the Great Lakes region. The latter part of this week finds that trough lifting a little northward as it moves over southern Quebec. A fairly strong surface high of Arctic origin formed behind this upper-level disturbance, bringing extreme cold conditions.
During the first few days of February, the short-range forecast shows this polar vortex continuing east and lifting north. This leads to warming temperatures for the Canadian Prairies for a brief period of time. However, a new upper-level disturbance is expected to drop southward over western Canada during the weekend, to be followed by another blast of Arctic air. This is not the main polar vortex this time but more of an offshoot. It should not be as cold as this past event has been, overall. This disturbance is expected to come southward further west than the polar vortex event at the end of January. So, while the extremes of this event may not equal the extremes of the prior event, the western areas should actually turn out colder with this new system. Also of note, we will see a period of snow ahead of this new cold outbreak, possibly heavy snow for a time.
The upper-level forecast for the time frame ending Sunday, February 10 shows a weaker polar vortex in northeast Canada; upper-level ridging nosing northward into Alaska and northwest Canada; and north-to-south flow between these two features over western Canada. This type of flow is generally cold as there is little, if any, influence from the moderating effects of the relatively warmer Pacific waters. It is also a drier flow for basically a similar reason.
The longer-range outlook suggests, that with a weakening El Nino pattern in the Pacific Ocean, and a high-latitude blocking high pressure pattern setting up, it is likely that the Prairies will continue to experience episodes of Arctic cold with little moisture during the last part of the winter season. We see below-normal cold lasting through February, and a fair to good chance this will also be the case in March as well.
It is a little too early to talk, with confidence, about the potential weather patterns this coming April and May when spring field work and early planting could begin. There are a couple items we will be looking at for that time frame. The first is the weakening El Nino in the equatorial Pacific.; the second would be a change in the status of the Pacific Decadal Oscillation. If realized, this combination of events in the Pacific could mean near- to above-normal temperatures across the Canadian Prairies this coming spring, with precipitation averaging near to below normal. This would likely be a welcome change, if the late-winter period turns out to be as cold as currently indicated. However, it would also do little to improve the soil moisture situation, which is still very dry in some areas in the region.
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