Over the next 2-3 weeks a gradual expansion of snow cover for much of the northern half of the U.S. is expected. Meanwhile, stratospheric warming may shift from the Eurasian side of the North Pole to North America spawning arctic air. Forecast confidence is LOW for that part of the forecast. However, expanding snow cover will invite a cold February ahead.

Excessive heat haunts the Argentina drought area this week. However, there are some heavy thunderstorms indicated for Central Argentina late this week due to a weak upper-level impulse and possibly more substantial rain next week as a cold front moves into Argentina.

La Nina is moderate strength right now. Weakening is expected. The weakening of La Nina occurs due to a transient tropical convection oscillation know as the Madden Julian oscillation (MJO) which shuts down trade winds and allows warm subsurface waters to shift eastward from the equatorial subsurface near and west of the Dateline. The second of 4 expected MJO events is occurring now.

Remarkably, despite a harsh arctic outbreak in December, the U.S. temperature averaged almost exactly normal and ranked 64 (of 128 years) which is right in the middle. The cold region was the Great Plains, Montana and Washington although not particularly impressive. Sixteen states were warmer than normal including MUCH ABOVE normal in Maine.