For the first time since November the Madden Julian oscillation is activated and intensifying in the equatorial Pacific Ocean into early February. The result is increased risk of excessive precipitation in the East-central U.S. and a mild climate pattern east of the Continental Divide as the final month of meteorological winter arrives.

Beginning midweek the northern hemisphere jet stream will trough on the U.S. West Coast and re-strengthen in western Europe. In-between the two vigorous trough patterns a third trough resides south of Greenland. By late January the pattern still remains although with slightly less amplitude. These features shape the last third of January 2021 climate for the northern hemisphere.

A December 2020 stratospheric warming event across Northeast Asia spawned a frigid polar vortex stretching from Mongolia to Northeast Asia. Beneath the polar vortex increasingly cold air was generated taking on arctic intensity. In late DEC/early JAN the cold air mass was ejected southeastward into China bringing historic snows and cold.

The more conservative view (by the HRRR model) indicates the heaviest snowfall in west-central Texas (6-10 in.) while GFS is much heavier northwest of Houston area (up to 10-12 in.). Given the strength of the upper trough and rapid cooling of the lower atmosphere late today/this evening the heavier (GFS) totals are favored!