Cold 2nd half to Winter 2018-19? MJO expected to enter cold phases as SSWE causes vortex split!

The pattern has been mild across most of the continents of the Northern Hemisphere with the aid of a continued amplified MJO progressing through phases 2,3,4 and 5 which supports a neutral to positive AO/NAO.

Though NOTHING is certain until we see the pattern evolve, there are more favorable atmospheric drivers/signals/components coming together which supports a very different second half to winter than the first. Even when that pattern develops, there is still the possibility that the cold misses us.

However, enhanced convection and thunderstorms associated with the MJO wave is now exiting the maritime continent and heading out over the Pacific as seen below.

The significance to this should be the creation to a big shift and new downstream change in the upper atmosphere throughout the hemisphere over the next 2-4 weeks.

The below graphic shows the difference to the upper atmosphere further north when the position of the MJO pulse progresses eastward.

It’s possible, if not likely that when the MJO was in a strong phase 1 and 2 with large scale thunderstorm activity over the Indian Ocean that this triggered the SSWE. That massive injection of heat into the stratosphere is expected to split the polar vortex into two by early January.

It could well be that until this physically happens (and if), the models won’t see any particularly cold blocky pattern until it’s right on our door and I expect it to be sometime between January 10-15. Remember that’s still over 2 weeks away.

What could make for a wild mid and late January is the potential for a favorable MJO in phases 7, 8 and 1 at the same time the vortex splits and that’s essentially what I’m counting in for my forecast to materialise. What did I say again? Warm December and turn to increasingly cold pattern through January.

As you can see, we’ve pushed through the warm MJO phases of 2, 3 and 4, triggering the initial SSWE and we’re now currently midway through 5 and heading for cold phases 6 and 7 just as the SSWE peaks.

Lagged composites show increasing eastern US and Western Europe cold.

Just remember that there’s a lot going on way above our heads even if we are walking around in light jackets just days from the beginning of another year. Models don’t SEE what’s going on above, hence why their showing little and bouncing between different solutions.  The big test is fast approaching…

Featured image: Aaron Stanley

Tags: , ,

Follow us

Connect with Mark Vogan on social media to get notified about new posts and for the latest weather updates.

Subscribe via RSS Feed Connect on YouTube

1 Reader Comment

Trackback URL Comments RSS Feed

  1. Kathleen says:

    Happy New Year! Super analysis as usual! All the science adds up. New Years Day Hot in Nashville at 70 degrees with Tornado Watch, Severe Thunderstorm Warnings, High Wind Advisories and heavy rain. We turned on the AC due to heat/humidity! Agree it will be great to see some actual Winter in 2019. Models don’t look all that promising at this point but then there appears to be some disconnect between the models and SSWE’s. Trusting it’s not a case of being careful what I wish for! May 2019 be wonderful for you and your family.

Leave a Reply