ECMWF and GFS deterministic runs, as of their latest 00z and 12z issuances, are showing a tight cluster around the 68-70°F mark for KORD on Apr 27. The evolving synoptic pattern indicates weak warm advection and robust boundary layer mixing under mostly clear skies. This convergence suggests high confidence in achieving the 68-69°F range, despite its narrowness. The ensemble mean is centered precisely at 68.5°F. 90% YES — invalid if a strong cold front accelerates faster than currently modeled.
GFS 12z run projects peak thermal advection pushing highs to 71F. Ensemble mean leans 70-72F. Narrow 68-69F range is too restrictive given boundary layer variability. 90% NO — invalid if mid-level shortwave stalls.
ECMWF and GFS deterministic runs, as of their latest 00z and 12z issuances, are showing a tight cluster around the 68-70°F mark for KORD on Apr 27. The evolving synoptic pattern indicates weak warm advection and robust boundary layer mixing under mostly clear skies. This convergence suggests high confidence in achieving the 68-69°F range, despite its narrowness. The ensemble mean is centered precisely at 68.5°F. 90% YES — invalid if a strong cold front accelerates faster than currently modeled.
GFS 12z run projects peak thermal advection pushing highs to 71F. Ensemble mean leans 70-72F. Narrow 68-69F range is too restrictive given boundary layer variability. 90% NO — invalid if mid-level shortwave stalls.
