This is first of two writings on the analysis of a Nor’easter. This writing will focus on how the storm system looks in the low levels (Surface to 700 mb). Height contours: Height contours are used to infer wind speed and direction. Closely spaced contours indicate stronger wind and wind vector are drawn on the image to show wind direction. A Nor’easter will have closely spaced contours encircling it. This indicates a deep mature system that has strong winds. Temperatures: With a Nor’easter there are relatively warm temperatures to its east and relatively cold temperature to its west. This powerful temperature gradient helps fuel the storm system. Cold core lows derive energy from a temperature gradient and latent instability promoted by the warm Gulf Stream waters over the Atlantic Ocean. Precipitation Type: The path of a Nor’easter is an important factor in determining the location of heaviest rainfall or snowfall. If the storm system is far enough offshore that cold air is present even at the coastline then this helps produce heavy snow in the major cities of the East. If the Nor’easter tracks further inland, then heavy rain is more likely in the major cities of the East Coast. Below is how a Nor’easter can look at 850 mb on a model panel: |