Communicating Potential High-Impact/Sub-Advisory Winter Events (295)

Christopher A Strong, NOAA/NWS/WFO, Sterling,


Steven M Zubrick, NOAA/NWS/WFO

Brian J LaSorsa, NOAA/NWS/WFO




Small amounts of snow over urban areas have the potential to create massive commuter gridlock when conditions are right. These small amounts of snow are often difficult to forecast. Forecaster confidence in occurrence of these events often comes after the point at which Departments of Transportation can be effective at mitigating the threat.

During the winters of 2016-17 and 2017-18, the National Weather Service's Baltimore Washington Weather Forecast Office (WFO-Sterling) collaborated with their regional transportation partners and the Office of Personnel Management (OPM) to create and test an experimental &ldquoPotential Winter Commuting Hazard&rdquo statement. The purpose of this statement, with its associated notifications, is to alert the community to the threat of a potential high-impact winter transportation event, with enough advance notice for society to take effective actions to mitigate the impact. This is often done many hours before there is enough confidence to issue formal warnings or advisories, and furthers our goal of communicating potential impacts to the public and core customers.

This presentation will describe what conditions are needed for a high impact traffic disruption from a minor winter precipitation event, what process the forecasters use to notify the community to the threat, and the necessary education component. There is also a real-world comparison of how the Washington D.C. metro area was severely affected from a January 20th 2016 event, versus the minor impact from a very similar event on January 4th, 2018.