For the 4th consecutive day, the weather was of the highest level around the central Midwest. With highs around 80, coats were nowhere to be found. Take a look at 3:00 PM temperatures. How sweet it was.

Many parts of the Midwest and Great Lakes were 25-30 degrees above normal

Notice the blue and green departures out west, not to be negative but that is is a sign of sharks in the water. They won't be swimming here right way but all the signals suggest a much cooler pattern is on the way as we push towards the middle of April.

The change all starts with upper level blocking at higher latitudes in Canada and Greenland. One of the first signs I look for when it comes to colder weather is the AO (Arctic Oscillation) entering a negative phase. That trend is now most pronounced now on the GFS.