“If only it were December” was probably a common expression amongst meteorologists, energy traders, and analysts yesterday as the 1200 GMT GFS produced a classic high latitude high pressure blocking pattern to cause a chilly longwave trough to appear in the East U.S. in the 11-15-day period.

During the week of Sep. 19-25, the verified temperature anomalies across Paraguay averaged an impressive +7C while interior Southeast Brazil was +4C to +7C. However, outside of this very hot region, the temperature anomalies for the week were not nearly as hot. Recent 1-5-day and 6-10-day temperature anomaly forecasts by GFS are much too warm incorrectly indicating too much anomalous heat.

The 2023 season so far is more active than normal with 17 tropical storms, 6 hurricanes, and 3 major hurricanes. The amount of activity so far and outlook for the remainder of the season implies the consensus seasonal forecasts will be accurate.

Certainly, a cooler pattern change can emerge at any time. However, the process of generating cooler pattern change is made more difficult by the much warmer than normal mid-latitude ocean surface.