A major cross country snow system during the past weekend produced record snow from St Louis to DC and this shall be followed by another three over the next 7 days.

GFS snow forecast through the next 10 days.

This stormy and increasingly colder pattern is the beginning to the much anticipated harsher 2nd half to winter 2018-19. A hemispheric response to the late December SSWE.

Since the SSWE officially occurred around Christmas with the reversal of winds at 10hpa, we’ve seen the vortex split into 3.

https://twitter.com/zd1awrence/status/1084935021171924992

Since this three way split, cold has descended through the stratosphere into troposphere and we’re finally beginning to observe the response with soaring heights throughout the Arctic. Over the next 2 weeks we should see the completion of twin ridges anchored over Alaska and Greenland as the cold troughs lock into place.

Snow totals were surprisingly impressive from the last storm.

https://twitter.com/Accu_Jesse/status/1084882054733533191

https://twitter.com/NWSStLouis/status/1084663035225169925

We’ve entered a colder and stormier pattern with an enhanced jet stream driving Pacific lows into the West Coast at the same time arctic air is beginning to push southwards. Pacific and eventually Gulf moisture merging with cold, dry Canadian air to the east of the Rockies is a perfect setup for storm intensification and major snowstorms as well as the opening of the freezer door.

Firstly, we have a major rain and snowstorm taking aim at California with several FEET of snow can be expected over the High Sierra while from Santa Barbara through the LA Basin into the mountains, we can expect upwards of 2-4, locally 6 inches of rainfall.

3-6 feet of snow could fall from Lake Tahoe to Mammoth Basin.

Overall setup.

See how the US pattern becomes progressively colder over the next 2 weeks according to the GFS ensemble.

Featured image credit: Jen Johnson @tPFmariah9999

Tags: arctic outbreak, coldwave 2019, polar vortex, SSWE, US Cold