Western Atlantic (Wallace–Gutzler)

½[Z*(55°N,55°W) − Z*(30°N,55°W)] on standardized Z500 anomalies (commonly cited WG81 coefficients). Positive = high heights over Labrador / low off the US East Coast. — Wallace & Gutzler 1981, Mon. Wea. Rev. 109, 784–812, doi:10.1175/1520-0493(1981)109<0784:TITGHF>2.0.CO;2