2025-2026 ENSO

[donsutherland1]

As previously noted regarding the February 15-28 period, what was fairly certain were:

1) Substantial warmup in the Plains States. 

2) Brief cool shot to the Southwest and then a return of warmer conditions. The cool shot likely won't be sufficient to preclude Phoenix from experiencing its warmest winter on record. 

The period has commenced with widespread above to much above normal readings in the Plains States. Phoenix is virtually certain to experience its warmest winter on record. Only one case saw in its period of record (1896-2025) saw a sufficiently cold February 15-28 that would miss the record. Nothing remotely close to that case is on the latest guidance.

 It was also noted that the Arctic Oscillation (AO) could hold the key to the overall outcome. The EPS and GEFS agree on the development of a WPO-, EPO+, PNA- pattern. During such patterns, conditions in the East tend to be much colder when the AO is negative than when it is positive. 

The latest AO forecast shows the AO returning to positive levels after a fairly short-lived dip to negative levels.

The most recent ECMWF weeklies show a brief return to cooler conditions in parts of the East during February 23-March 2, but a return to above normal temperatures afterward unlike prior runs. The weeklies also show most of the CONUS experiencing above normal temperatures to start March.

ECMWF Weeklies:

The CFSv2, which was been showing above normal temperatures on a consistent basis, shows a warmer than normal first week of March.

It's too soon to pronounce the end of Winter 2025-2026. There may yet be cold periods and snowfall, though the most severe cold is almost certainly behind us. But even if this latest guidance were to mark the end, many parts of the Northeast and Great Lakes Region had highlights that made this winter memorable, particularly sustained cold not seen for a decade or longer, long-lived snow cover, and from Philadelphia to Boston, a big snowstorm.