Baltimore no means uncommon for the rain-snow line to set up in the metro area. Freezing rain and sleet occurs a few times each winter in the area, as warm air overrides cold air at the low to mid-levels of the atmosphere. When the wind blows from the east, the cold air gets dammed against the mountains to the west and the result is freezing rain or sleet. Spring and autumn are warm, with spring being the wettest season in terms of the number of precipitation days. Summers are hot and humid with a daily average in July of , and
NEXRAD tornado detection and subsequent warnings. WSR-88D sites across the nation have been upgraded to polarimetric radar, which adds a vertical polarization to the traditional horizontally polarized radar waves, in order to more accurately discern what is reflecting the signal. This so-called dual polarization allows the radar to distinguish between rain, hail, and snow, something the horizontally polarized radars cannot accurately do. Early trials showed that rain, ice pellets, snow, hail, birds, insects, and ground clutter all have different signatures with dual polarization, which could mark a significant improvement in forecasting winter storms and severe thunderstorms. The deployment of the dual