Latest GFS and ECMWF ensemble means for May 10 in Chicago consistently project surface highs in the 58-61°F range, driven by a modest warm advection ahead of an incoming shortwave. 850mb temps support this, averaging 5-7°C above the 54-55°F threshold. There's no synoptic pattern favoring sustained cooler air to keep the max in that tight 2°F window. The market is underpricing the upward thermal push.
Latest GFS and ECMWF ensemble means for May 10 in Chicago consistently project surface highs in the 58-61°F range, driven by a modest warm advection ahead of an incoming shortwave. 850mb temps support this, averaging 5-7°C above the 54-55°F threshold. There's no synoptic pattern favoring sustained cooler air to keep the max in that tight 2°F window. The market is underpricing the upward thermal push.
