Forecast charts in late January are showing a healthy dose of cold air for February. For comment on the dynamics, DTN Meteorologist Nathan Hamblin from our long-range forecast group authored the following details.
A major pattern change is imminent across North America as we turn the calendar to February. An anomalous warm high pressure ridge will set up along the West Coast of North America. Downstream impacts will feature an anomalous low pressure trough over eastern North America. This will evolve into a pattern that is very similar to what occurred late-December through the first half of January across the United States.
The 11-day analog forecast centered on the first week of February looks very similar to the 11-day analog forecast shown for the end of December. In addition, DTN examined years that featured a similar large-scale pattern to what has occurred in early 2018. The temperature and precipitation patterns look very similar. These factors give DTN meteorologists higher confidence that a similar evolution is coming.
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This episode is likely to last somewhere around three weeks, with maximum impacts from Feb. 5 to 25. Cold arctic air will be dislodged from the polar regions and will surge southward across central and eastern North America. This cold will likely penetrate into the Deep South at least two times in a similar fashion. Sub-zero temperatures could push well down into the Central Plains through the Ohio Valley at the peak. The fact that we are pushing through February with longer daylight hours may take the edge off the cold somewhat versus what happened in late December and early January.
This pattern will also feature anomalously dry conditions across a large portion of the country. The dryness will be prevalent across the Central and Southern Plains and the Middle Mississippi Valley. Despite the dryness, there will be risks for wintry precipitation to push along strong cold fronts well down into the Southern Plains and perhaps toward the Gulf Coast. We should see minor clipper systems that will deposit occasional light snowfall across portions of the Northern Plains and the Upper Midwest. These events are not likely to eliminate any deficits. On the other hand, near-normal precipitation will be likely across portions of Montana and perhaps into the western Dakotas. The Lower Mississippi Valley region is likely to see above-normal precipitation. Anomalously dry conditions are likely along the West Coast for the balance of February.
The West Coast ridge is likely to break down toward the very end of February, and the arctic cold and persistently dry conditions should relent for most as we get into the first week or so of March.
Thanks very much to Nathan Hamblin for these comments. Takeaway points are: A ridge west-trough east pattern is indicated to form over North America in early February. This pattern is very similar to the pattern that dominated the scene back in December. It is likely to bring a new round of very cold air for the season to the central and eastern U.S. Precipitation will focus over the southeastern Plains and eastward. There is little to no meaningful precipitation in the driest areas of the southwestern Plains with this pattern.
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