Sudden Stratospheric Warming 2016/2017 ?

sryanbruen wrote: »

A technical BUT an extremely weak SSW. The zonal winds at 10hPa are -0.1 m/s which is very weak and could potentially be the weakest SSW on record unless they go more negative over the next few days but I don't expect any further drops, I expect the zonal winds to go back into positive territory.

Meanwhile, the AO is trending very negative up to 16 February. Very interesting but unfortunately, the NAO is still trending rather positive and for a better chance of a sustained cold spell, you need the NAO to go negative.

That's true.
It's a weak warming because of the westerly QBO state- that is why the NAO is likely staying positive too. The one thing on our side is the size of the block, although with a positive NAO and the vortex forecasted to quickly recover due to the weak reversal, the odds of the Atlantic getting back in over us is high. England, as always, has a greater chance of holding on to a continental feed. Still i wont complain at all if only we get a 2- 3 day cold spell with heavy snow showers

This winter will go down as the winter that promised so much but gave F all

UK people could be in for a February 1991 situation as the Polar Vortex looks like being properly split despite the SSW being extremely weak unlike in 2013. I'd like to thank the guys at Netweather for sharing this chart from January 1991.

This chart in the attachment below shows some very significant warming at the end of January 1991 much like what happened in January 2017 but unlike this year, the 1991 warming wasn't considered a SSW. Nevertheless, due to how weak the SSW is in 2017, it is very similar to 1991's warming.

For anybody that doesn't know, February 1991 started off exceptionally cold across the UK in particular with the cold far less intense over Ireland but it was still colder than normal. Around the end of the first week, snow started to show its hand across the east of Ireland and there were some heavy falls. After around 2 weeks of bitterly cold conditions, however, the Polar Vortex reformed and we got a much milder and wetter end to February 1991 with 13c on the 23rd. Read more about it here:

https://drive.google.com/file/d/0BwAX53FX4EFMVEdtbTRFTDRCdjQ/view?usp=sharing

Before January & December 2010, February 1991 was the last month in England to record a mean temperature of less than 2c.

February 1991 was not the most severe cold or snowy month by any means but I'd take it if I were offered it .

GFS is now showing another significant warming to take place through the 3rd to last week of February. This one looking like disrupting the Polar Vortex more abruptly.

I'll leave this for greater minds than mine to interpret.

Could this mid-March cold spell that's being shown by the models be the response to the Stratospheric Warming?

nacho libre wrote: »

The guys over on the Netweather Stratosphere thread believe there is usually a two- three week lag period before the effects begin to show up in the troposphere.
As i mentioned in the other thread, the uk met office must, to commit to a cold spell at this stage, be picking up a strong signal from their own model.

Of course it will all go pear shaped in the end:pac: At this time of year it does not bother me if that happens, as without the perfect set up it will be cold rain or sleet, rather than snow that gives accumulations at lower levels.

So there was no response to the January SSW (which was extremely weak)?

nacho libre wrote: »

I think there was, remember that brief weak south easterly flow we had due to the scandi high, which quickly sunk.

You thought that was the response? I thought that was way too fast for a response to the SSW.

It looks as though the response to the late February stratospheric warming is taking place now except in the USA where the eastern seaboard is much colder than normal and a nor'easter will take place in the coming days bringing blizzards. This is a contrast to the warm Winter they recorded. Meanwhile, temperatures at home are expected to go back down to average or stay slightly above for the next 7-10 days after a warm weekend.