Today’s afternoon readings in the upper 50s were coolest since April 29th….136 days ago! And our weather pattern has shifted into a flow that will bring cold fronts a lot faster…and with chillier air! If the afternoon model runs are correct…we could see morning lows in northern Missouri hit the 30s as early as next Tuesday.
The strong ridge of high pressure aloft that was responsible for the hot dry summer…has basically shifted a bit to the west…and the result is a rapid switch to a pattern that allows an open flow of air across central Canada and down into the plains. Here’s a look at the global 10 Day forecast for the 500 millibar pattern (approximately 18,000 feet) which is valid for Sunday September 23rd:
The European model is on the left…the American GFS model is on the right….but what’s important is that they are in fairly close agreement! This pattern…with two distinct vortices…one over the north Pacific…and the other over eastern Canada…locks this pattern into place for at least the next 20-30 days. There will be frequent cold fronts…with brief warmups…and more days of below normal temperatures, than above normal days.
This may be the pattern that we run home to during the upcoming winter. The sea water temperature anomalies would suggest that is the case. In the latest global imagery showing the anomaly pattern, you’ll notice the extremely warm waters over the North Atlantic Ocean.
This large area of warm water will help force a negative North Atlantic Oscillation…trapping colder air across central and eastern Canada…where it can build up…then drop south into the central U.S.
One interesting note: this warm water is part of a normal cycling of warm and cold waters in the Atlantic basin. And every time this occurs…you do see a rapid melting of sea ice. You may have read articles about the “record low” levels of northern sea ice…and this warm water along with active volcanoes under the sea along the Gakkel Ridge are responsible for the melting.
In addition to a cooler North Atlantic which allowed the cold air to drain into the North Atlantic last year…thus limiting the cold outbreaks…and snowfall from last year….you’ll also notice the cold water in the tropical Pacific. That’s the La Nina pattern, which has reversed since last fall. So it’s pretty clear that we will not see a repeat performance of last winter’s warmth…but this pattern would allow for some warm intervals over a winter….so it will be colder than last winter…but what about snowfall? Let’s find a proxy:
What was the snowfall that year? 14.6″! Normal is now: 18.8″ Last winter was only 3.9″!
Of course it’s a little early to make a call on winter…but these are some preliminary thoughts I’ve had based on the data available to consider. But after a 30 degree plunge from yesterday…thoughts of the season ahead certainly start emerging in my mind…so I thought I’d share what I’m seeing right now with you!
Have a great Friday!