MEAN FIVE-DAY PRESSURE PATTERN OF THE GREAT ATLANTIC COAST STORM, MARCH 1962

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  • 1 U.S. Weather Bureau, Washington, D.C.
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Abstract

A mean sea level pressure map is drawn for the North Atlantic Ocean for the period of the Atlantic Coast storm of March 5–9, 1962 and anomaly and normalized departure charts are presented. A comparison is made with the January 8–12, 1956 storm during which some of the greatest pressure anomalies associated with severe extratropical coastal storms of the 20th century occurred. It is noted that in the typical northeaster a ridge usually extends east-southeastward or southeastward over the North Atlantic Ocean from a High located over eastern Canada and Labrador. The ridge was very weak in the March 1962 situation and the resulting pressure pattern produced winds with easterly components of an unusually long fetch from the British Isles to the coastal waters of the United States.

Return periods or mean recurrence values were computed, from an extreme value probability analysis based on 17 years of 5-day mean sea level pressure grid point data, for the intensity of cyclones and anticyclones associated with the March 1962 and January 1956 storms. The extreme easterly flow was computed between 35° and 45° N. from 55° to 75° W. and return periods of 18 years and 11 years were found for the January 1956 and March 1962 storms, respectively.

Abstract

A mean sea level pressure map is drawn for the North Atlantic Ocean for the period of the Atlantic Coast storm of March 5–9, 1962 and anomaly and normalized departure charts are presented. A comparison is made with the January 8–12, 1956 storm during which some of the greatest pressure anomalies associated with severe extratropical coastal storms of the 20th century occurred. It is noted that in the typical northeaster a ridge usually extends east-southeastward or southeastward over the North Atlantic Ocean from a High located over eastern Canada and Labrador. The ridge was very weak in the March 1962 situation and the resulting pressure pattern produced winds with easterly components of an unusually long fetch from the British Isles to the coastal waters of the United States.

Return periods or mean recurrence values were computed, from an extreme value probability analysis based on 17 years of 5-day mean sea level pressure grid point data, for the intensity of cyclones and anticyclones associated with the March 1962 and January 1956 storms. The extreme easterly flow was computed between 35° and 45° N. from 55° to 75° W. and return periods of 18 years and 11 years were found for the January 1956 and March 1962 storms, respectively.

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