THE OLD FLIP FLOP....ARGH!
For about a week both the GFS and the EURO were bullish on digging a deep trough into the Midwest about October 11th. The end result was to be the first real punch of cold air that would bring widespread frost and even freezing temperatures. As recently as yesterday the EURO was sill adamantly showing such a development.
Today, no such thing as both models have split the trough and the lack of phasing cuts the cold off keeping it safely to the north near the Canadian border. I must say after a week of consistency that was a big shock, I sure didn't see it coming. Let me show you the comparison of yesterday's EURO to today's.
Here's the cold 500 mb trough yesterday.
Here's the split that popped up today. What a radical change.
The associated temperature anomaly at 5,000 feet yesterday. Very chilly stuff with highs barely above 50.