Stratosphere watch 2018/19

A little change now with winds not quite reversing



Image is live so will update as it changes.

sryanbruen wrote: »

Very strange. ECM 10hPa zonal winds are now reversing in its forecast.

If the zonal winds do not reverse, this won’t be a technical SSW. Albeit, that chart is 65 degrees North, it’s 60 degrees North we look at (I only noticed I made that mistake yesterday).

The 60N chart is very similar:



Interestingly, the operational GFS 6z does seem to have backed off somewhat, with the warming peaking at 132h, and no real signs of a split. The Fv3, on the other hand, has now gone full split towards the end of FI.

Let's hope the FV3 turns out to be the superior model, which is what one would surely expect given that it's to replace the operational in the coming months.

Op:



FV3:

BOOM!!! :cool: :cool: :cool:



Now, let's see this creep ever closer over the next few runs and not run away from us

Arctic Oscillation and Polar Vortex Analysis and Forecasts

December 17, 2018

Summary

• The Arctic Oscillation (AO) is currently neutral and is predicted to straddle neutral right into the new year.
• The current neutral AO is reflective of mixed pressure/geopotential height anomalies across the Arctic and mixed pressure/geopotential height anomalies across the mid-latitudes. The North Atlantic Oscillation (NAO) is currently also near neutral with weak positive pressure/geopotential height anomalies across Greenland and mixed pressure/geopotential height anomalies across the mid-latitudes of the North Atlantic and is predicted to remain close to neutral over the next two weeks.
• Troughing/negative geopotential height anomalies across much of Europe is bringing near seasonable temperatures to below normal temperatures currently but in general ridging/positive geopotential height anomalies will increasingly dominate much of Europe over the next two weeks resulting in normal to above normal temperatures starting in Western Europe including the United Kingdom (UK) and spreading eastward.
• Building ridging/positive geopotential height anomalies centered across Scandinavia and the Barents-Kara Seas will force downstream troughing/negative geopotential across large parts of Asia. Normal to below normal temperatures are mostly focused across Western Asia including much of the Middle East and the Indian subcontinent but will slowly spread eastward to eventually include Central and East Asia.
• Troughing/negative geopotential height anomalies across Alaska and the Gulf of Alaska will help to focus troughing in the western part of North America with mostly ridging/positive geopotential height anomalies downstream across eastern North America. Cold temperatures will be mostly confined to Alaska this week but will start spreading south and east first across western Canada and then the Western United States (US). Meanwhile temperatures will mostly average normal to above normal in Eastern Canada and the Eastern US.
• In the Impacts section, I discuss my observations for the large-scale pattern and temperatures across the Northern Hemisphere related to troposphere-stratosphere-troposphere coupling.

source

The split is gone on the 12z FV3, but it's still showing the PV squeezed into a figure of eight shape, just ready to split if it comes under more pressure.

I don't see why there's so much hullaballoo over one day of slight downgrades tbh. The warming is still on track and FI is always going to flip and flop during an event like this... To look at NetWeather this afternoon you'd swear we've just seen a freakishly early start to Spring

A split and a second warming would be interesting!

With a split vortex, highly likely we would get a cold spell. As soon as the decorations are down I reckon then the models will light up.

Billcarson wrote: »

With a split vortex, highly likely we would get a cold spell. As soon as the decorations are down I reckon then the models will light up.

A much greater chance than if it were a displacement, it's still not a guarantee as the daughter vortices could end up in the wrong place- for example if blocking ended up too far west- in whats called a west based nao. I think if we do get a cold spell around mid- January it maybe extended by a weak el nino aiding further blocking to develop