Communicating the Reasonable Worst-Case Scenario for Rush Hour Planning

Winter storms are notorious for disrupting travel and commerce. While the finer spatial and temporal details may be difficult to predict far in advance, the mention of a high impact, strong system such as a nor’easter often comes early, affording planners the benefit of preparation time. Occasionally, a weaker system with less predictability and less notice can result in unexpected, yet significant impacts. On 15 November 2018, rush hour snowfall totaling from 4 to 8 inches across metropolitan New York City (NYC) resulted in some afternoon commutes lasting more than 10 hours. Slick road conditions led to a complete standstill on the George Washington Bridge in NYC, while students sheltered in place overnight in West Orange, New Jersey as numerous vehicle accidents prevented school buses from arriving at school. Despite snow in the forecast, and ample Impact Based Decision Support Services provided by WFO New York, NY to core partners, the forecast was labeled by some in the community as a “bust”. For New York City in particular, the event led to a procedural change to the questions the NYC Office of Emergency Management personnel asked National Weather Service meteorologists in their daily consultations for the reminder of the winter.

An overview of the meteorology and forecast decisions leading up to the 15 November 2018 event will be provided, followed by a summary of the lessons learned. While local decision-makers would like to know the worst case scenario for any event, such as any outlying ensemble member information, the author will provide strategies developed locally to communicate the differences between this worst case and a reasonable worst case scenario.

Finally, the author will provide suggestions for effective communication and rebuilding trust after the perceived forecast bust based on this event.