Progressive MJO Sustains Cold U.S. Pattern

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Extended-range forecast models are very warm across the U.S. However, a moderate-to-strong progressive Madden Julian oscillation, continued negative phase of the arctic oscillation and expanding snow cover implies and warm-ups will be brief and overall the U.S. stays cold into Thanksgiving week.

Progressive Pacific-to-Atlantic MJO coupled with negative AO implies U.S. cold pattern to continue

Fig. 1-2: The NCEP 14-day MJO forecast indicates a progressive and strong feature shifting from the equatorial Pacific to western Indian Ocean tropics. MJO phase 7/8 and phase 1/2 favor mostly colder than normal climate across the U.S. during November.

Discussion: The morning MJO forecast indicates a moderate-to-strong intensity the next 14 days and progressive character shifting from the equatorial Pacific this week to the western tropical Indian Ocean in 12-14 days (Fig. 1). Based on climatology this MJO regime occurring in November favors a cold northern U.S. pattern while the MJO is in the tropical Pacific followed by a cold shift to the West U.S. as MJO moves across the equatorial Atlantic and then cold into the East once MJO reaches the western Indian Ocean (Fig. 2). The MJO sequence identified coupled with a persistent negative phase of the arctic oscillation (Fig. 3) implies the U.S. pattern is likely to stay colder than normal in the extended-range with limited and brief warm-ups.

Fig. 3: The NCEP 14-day AO forecast indicates sustained negative phase which represents high latitude blocking and favors colder climate in the U.S.