A pattern change

For most of the spring, the country has been plagued by a broad, slow moving wave right across the center of the country. It’s been spectacularly unpleasant, with Arctic air lingering over the continent of North America for the last couple of weeks, introducing record lows and several late season snow storms.

Fortunately, the tide seems to be turning. The mean jet flow is finally forecast to shift north, indicating that the chilly air will finally be pent up where it belongs, at least for the long term. As you can see with the forecast jet stream analysis for Monday, the continuous stream lies just north of the Canadian border.

Thee will still be a threat for a cold air invasion late next week, but not nearly on the scale that we’ve seen for the beginning of the month, as the pattern has become much shorter in wavelength. Any period of cooler air will be briefer, and won’t be able to sneak as far south.

The jet is retreating, along with the cold air, but it isn’t switching pattern immediately. The northern part of the country is simply moving closer to normal, rather than suddenly moving above normal.