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12/02/2018, 11:13 am EST

MJO Outlook: Support for Warming Extended-range

Discussion: A lead mode of climate variability, the Madden Julian oscillation (MJO is forecast to shift east from the East Pacific/Atlantic tropics to the Indian Ocean during the first half of December (Fig. 1). In December the historical relationship of the MJO shift into Indian Ocean favors a wet (and snowy) U.S. pattern (Fig. 2) and a gradual warming bias (Fig. 3). Do the operational models match the MJO climatology? The 15-day precipitation forecast by all models agree with the MJO climatology as emphasized by the ECM ENS (Fig. 4). Very wet (and snowy) conditions including excessive amount affect the West Coast and the Gulf region plus the East U.S. in the 15-day outlook. The heavy precipitation forecast includes abundant snowfall the next 10 days (Fig. 5) which pushes cold temperatures (Fig. 6-7). However, if the MJO shifts farther east across the Indian Ocean the 11-15 day forecast should trend warmer (Fig. 8). Fig. 1: The 2-week MJO forecast indicates a shift from the Atlantic (P1) to Indian Ocean (P2) tropics possibly further east (P3) days 11-15. Fig. 2-3: The correlation to a MJO transit from the Atlantic (P1) to Indian Ocean (P2) and possibly further east in the Indian Ocean (P3) and the temperature/precipitation climatology. Fig. 4: The ECM ENS precipitation amount forecast across the U.S. the next 15 days. Fig. 5: The ECM ENS 10-day snowfall forecast across the U.S. Fig. 6-8: The ECM ENS day 1-5 (top left), day 6-10 (top right) and day 11-15 (bottom) U.S. 2-meter temperature forecast.