Progressive MJO Pushes a Warm to Cold U.S. Thermal Transition

Highlight: Eastward shifting MJO causes warm to cold extremes across U.S., Warm Europe 15-day forecast trends warmer.

Fig. 1: Steady eastward progression of the MJO across the equatorial Pacific Ocean while weakening is indicated by all forecast models over the next 2 weeks.

Discussion: The very warm forecasts for the Central and East U.S. through he next 7-10 days continues. One of the catalysts for the anomalous warmth is the position of the Madden Julian oscillation (MJO) in the central tropical Pacific Ocean. The MJO is also the catalyst for the storminess across the West U.S. the next 7-10 days featuring widespread snows and ability to generate a cold air mass in Southwest Canada to the Northwest U.S. The progression of the MJO eastward during the next 2 weeks (Fig. 1) implies the weather pattern will also shift eastward. Consequently, in the 11-15-day period a cold outbreak into the Central U.S. including Texas is likely (Fig. 2). The risk of <18F will certainly extend across the northern and western Great Plains with this outbreak (Fig. 3).

Fig. 2-3: GFS ENS indicates a cold outbreak across the Great Plains in the 11-15-day period also featuring southern reach of <18F risk.

In Europe, the trend is warmer to an already warm forecast (Fig. 4). The culprit is a developing and intensifying upper-level low-pressure trough southeast of Greenland (Fig. 5) associated with the returning North Atlantic warm hole (NAWH). The NAWH is a semi-permanent large pool of cool SSTA having a tendency for correlation to an upper-level trough to the west of Europe.

Fig. 4-5: ECM ENS is warmer in their 15-day temperature anomaly outlook for Europe thanks to a persistent upper-level high-pressure ridge.