Light precipitation will begin to move inland on Friday morning, mainly impacting the northern and central Sierra with rising snow levels initially around or above 5000–6000 ft. Steadier snowfall will develop late Friday into Saturday as a surge of Pacific moisture arrives.

A weak La Nina event has arrived in the Pacific, bringing colder waters and potentially cooler weather. Despite being delayed and relatively weak, La

With a weak La Niña returning in the equatorial Pacific, our weather across the Great Lakes could turn more active for the remainder of winter.

Significant snow totals will likely be from the Cascades of the Pacific Northwest, Western BC, and the northern Rockies.

In a La Niña pattern, the trade winds push warmer water toward Asia and bring cooler waters to the west coast of the U.S. This typically means dry weather, warmer conditions and drought for the southern U.S. and cooler temperatures for the Upper Midwest and Pacific Northwest.

By Shanna Hanbury It’s official: a weak La Niña came into fruition in late December and is expected, with significant uncertainty, to last until sometime between February and April, the U.S. National Oceanic and Atmospheric Administration announced.

We are halfway through winter and after an exceptionally warm start, North America’s winter is transitioning toward more predictable patterns with La Niña.

La Nina, the cold side of the El Nino Southern Oscillation (ENSO), typically results in colder conditions across the U.S. Northern Plains and Canadian Prairies, while it remains warm across the southern tier of the U.S. Precipitation tends to favor the Pacific Northwest and the Ohio Valley while the southern tier is drier overall.

La Niña has arrived and is likely to be impacting the winter season, including how much snow and rain New England might see before the start of spring.

La Niña is usually associated with drier conditions across the southern part of the U.S. and wetter conditions to the north. This reflects how La Niña is associated with a more poleward-shifted jet stream that deflects the storm tracks to the north (both Emily and Tom have written some nice explainers).

There is a 59% chance for La Niña conditions until April with weak and short typhoons also likely to occur in the coming months, the state weather bureau PAGASA said Thursday.

CPC and BoM monitor La Niña conditions, with ONI values indicating potential emergence, while ENSO remains neutral.