A downslope windstorm in New Jersey? An analysis of the 4 January 2009 high-wind event

During the early morning hours of 4 January 2009, an unanticipated strong wind event occurred. Despite a zone forecast calling for winds less than 10 mph (4 m s^-1) issued four hours prior to the event, winds up to 51 mph (23 m s^-1) were reported at High Point, New Jersey (elevation 550 m) as well as in its immediate lee (elevation 311 m). These winds were highly localized, with a nearby ASOS station (Sussex, NJ, 12 km distant) reporting calm winds between 07 and 10 UTC, just as the winds were peaking near High Point. High Point is the highest point in New Jersey, and is part of the quasi-two-dimensional Kittatinny Mountain extending from Pennsylvania into New York, thus making mountain wave activity, and perhaps a form of downslope windstorm, a potential culprit. This study tests this hypothesis by bringing together all known observations of the event, a high-resolution run of the Weather Research and Forecasting model, and mountain wave theory in an attempt to explain these unusual winds. The predictability of this event will also be considered.