Helped by a strong positive phase of the Arctic Oscillation and North Atlantic Oscillation, we have a strengthening west-east jet stream crossing the Pacific, providing a lot of energy to drive across the United States this week.

As a consequence to this 190+ mph jet this week, we’ll see the first ‘series of storms’ batter the West Coast with hurricane-force gusts, flooding rain and heavy mountain snow. This strong push of Pacific east will warm considerably to the lee of the Rockies and we are likely to see record warmth, very mild through the Ohio Valley and East Coast.

A LOT of moisture to pile into the Pacific Northwest this week with this hosepipe, AKA ‘atmospheric river’ pointing directly at Seattle and Portland.

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The latest GFS surface/precipitation charts below through the next 168 hours showing the energy and moisture piling into the West and looks set to drop a solid few feet of snow over the Sierra.

Significant snowfall expected over the next 7 days alone widely over the Intermountain West from Sierra to Colorado Rockies.

Some spots may get close to 50 inches.

Good news for the drought.

The really warm weather spreads into the Eastern two thirds once the upper low gets east of the Rockies and forces the ridge out into the Atlantic, this provides a strong SSW flow and may send 70s as far north as Chicago, Cleveland, Pittsburgh and even New York City late week into the weekend.

December sure has gotten off to a warm start.

See this morning’s video for the discussion.

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