Examining Vertical Velocities in the Dendritic Growth Zones of WRF Simulations of High Impact East Coast Winter Storms

Mesoscale snow bands, which can produce locally heavy snowfall rates within powerful snowstorms, can often be difficult for a numerical weather prediction model to accurately depict and predict. One feature that may enhance snow band growth and development is strong upward motion within the dendritic growth zone (DGZ). The DGZ is located between the -12°C and -17°C isotherms in the vertical, and is the area at which dendrites can grow depending on moisture availability and vertical velocity. Using an ensemble of Weather Research and Forecasting Model (WRF) simulations of snowstorms during NASA IMPACTS field campaign, this study aims to correlate the max vertical velocity within the DGZ to that of highest snowfall rates. This study will help to determine whether or not one can fully rely on this metric for forecasting. Additionally, this study compares the observed synoptic features, snow band placement, and vertical velocity captured by conventional observations and the NASA IMPACTS flight team, against the WRF simulations. A hypothesis is that spatial dislocation of snow bands by the WRF model could be due to the inaccurate representation of mesoscale processes for example the depiction of vertical velocity in the DGZ.