Great Appalachian Storm of November 1950 - Synoptic History

Synoptic History

The preceding atmospheric state was one of La Niña conditions, the cold phase of ENSO, which favors a storm track from the Ohio and Tennessee Valleys into the Appalachians. The cyclone initially formed in southeast North Carolina near a cold front on the morning of November 24 as the main cyclone over the Great Lakes weakened. Rapid development ensued as the surface center began to migrate back into a closed 500 hPa (14.75 inHg)-level (around 6,000 m/20,000 ft above sea level) cyclone, and the cyclone bombed while moving north through Washington D.C. the next morning. The former occluded front to its northwest became a warm front which moved back to the west around the strengthening, and now dominant, southern low pressure center. By the evening of November 25, the cyclone retrograded, or moved northwestward, into Ohio due to a blocking ridge up across eastern Canada. It was at this time that the pressure gradient was its most intense across southern New England and eastern New York. The cyclone moved west over Lake Erie to the north of the upper cyclone before looping over Ohio as the low-level and mid-level cyclone centers coupled. Significant convection within its comma head led to the development of a warm seclusion, or a pocket of low level warm air, near its center which aided in further development due to the increased lapse rates a warmer low level environment affords under a cold low. After the system became stacked with height, the storm slowly spun down as it drifted north and northeast into eastern Canada over the succeeding few days.