THE MAP ROOM CHARACTERISTICS OF CLOUD AND PRECIPITATION PLUMES OVER THE CHESAPEAKE BAY

OCTOBER 2003 AMERICAN METEOROLOGICAL SOCIETY | ake-effect and ocean-effect clouds and precipitation are well-documented mesoscale phenomena that can significantly impact the weather in coastal regions. The Chesapeake Bay is a large marine estuary that extends from Maryland to southeastern Virginia (Fig. 1), where the mouth opens to the Atlantic Ocean north of Hampton Roads (Newport News to Virginia Beach). Chesapeake Bay is approximately 240 km long and ranges from 15 km wide in Maryland to over 30 km wide near the mouth in southern Virginia. The complex coastline encompasses many smaller bays and expands the lateral coverage of water to over 65 km in the Virginia portion. Cloud and precipitation plumes can develop in the Chesapeake Bay, similar to the mesoscale phenomena observed in the Great Lakes and Atlantic coastal areas. These plumes can impact aviation and marine interests, enhance synoptic rainfall or snowfall, and sometimes produce waterspouts. The effects are very localized, yet can have significant impact on a population of over 1 million people, including a large segment of our nation’s military. Due to the narrow range of thermodynamic and kinematic conditions that support their development, bay plumes occur most frequently from the fall through spring. Plume formation is normally associated with postfrontal strong low-level cold temperature advection. Bay water temperatures are also climatologically warmer than air temperatures during this period. Air–sea temperature differences can support development of bay plumes that affect the Hampton THE MAP ROOM