ALERT: MJO Set-up Triggering January Arctic Outbreak Returns Middle February
Discussion: The ECMWF 30-day ensemble forecast indicates the Madden Julian oscillation (MJO) returns to phase 7 (equatorial West Pacific Ocean) Feb. 8-16 (Fig. 1). The model indicates an amplified signal which is impressive given the signature is at the end of the 30-day forecast when climatology tends to suppress the forecast result. The last time MJO shifted through the equatorial West Pacific Ocean a stratospheric warming event emerged, arctic air was generated and the U.S. suffered following bitter cold (Fig. 2). The set-up for the same regime returning mid-February is emerging based on this forecast. A February arctic outbreak would be much less intense than early January nevertheless more unwanted cold for areas in the Central and East U.S. hit hard by cold and snow this winter season. Ahead of this still potential event the U.S. is warm into early February followed by the cold pattern change. The NCEP CFS V2 EIA week 5 forecast provided by CWG/Storm Vista WX models identifies the potential cold (Fig. 3) and Climate Impact Company agrees.
Fig. 1: ECMWF 30-day MJO forecast indicates returning phase 7 Feb. 8-16.
Fig. 2: The last phase 7 helped to ignite arctic air formation in Canada.
Fig. 3: The NCEP CFS V2 weekly U.S. temperature anomaly forecast indicates Feb. 16-22 arctic air risk.