Description:
The maps above show the monthly velocity potential anomaly at 250 (top) and 925 hPa (bottom) standardized by the standard deviation for the given month over the 1971-2000 climatology (grey contours). The shading for the anomalies starts at +/-1 standard deviation; the color contour interval is 0.5 s.d. Positive anomalies are shown in yellow and orange; negative anomalies in shades of blue. The contour interval for the climatology is 1.0E+6 m2/s; solid contours indicate positive values and dashed contours indicate negative values. NCEP is an acronym for the U.S. National Centers for Environmental Prediction.