NWS WFO Mount Holly, NJ
Abstract
On January 30, 2019, a line of intense snow squalls affected a large portion of the Northeast and
mid-Atlantic United States. These squalls were noteworthy for their cohesive linear structure and
unusually long duration which allowed them to impact a wide area. They were also well forecast
and serve as an example of the benefits of the “forecast funnel” approach. Here, the evolution of
these squalls on January 30 is examined from a primarily operational perspective. Attention is
given to the large scale drivers of the squalls, their mesoscale evolution, and the unique
challenge they presented to forecasters as they evolved. Focus is placed on why these squalls
were so widespread and intense, with emphasis on factors such as a uniquely favorable pre-
squall synoptic environment and the presence of a shallow but well-mixed boundary layer. Also
discussed are some of the observational limitations that made real time monitoring of this event
challenging, including a lack of data over much of east-central Pennsylvania and the shallow
nature of the squalls which made tracking them by radar difficult to impossible at times. While
the snow squalls of January 30, 2019 were well forecast, it is hoped that performing this case
study will provide additional value for forecasters during future snow squall events.
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