Using simulated satellite imagery for a null CAWS day

The second of the 2015 experiment began on an active, yet quiet day as far as CAWS was concerned. Participants viewed forecast data for later in the day and evening, including the simulated imagery from the NAM Nest. The 2200 UTC forecast is shown below.

20150817 2200 UTC NAM Nest IR forecast

The area of concern was Chicago, and whether the expected convection would impact the terminal during the evening push of flights. By 1900 UTC, the forecast showed a line just north of the terminal, extending back to Omaha (bold dashed line). At 0000 UTC on the 18th, the forecast still showed convection staying north of the terminal.

20150818 0000 UTC NAM Nest IR forecast

Data from other models were fairly consistent, indicating the convection will remain north of the terminal until after 0000 UTC on the 18th. Because the evening push of air traffic will already be out and the busiest gates (south and east) around ORD will remain unaffected, the impact was deemed minor enough that a CAWS was not needed.