sebastiaan1973

What a waist of a -general terms- excellent set up.

In my opinion we were on the right track with this article: https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020RG000708 "For SSWs that are dominated by EuBL around their onset, cold anomalies prevail over northern Europe, albeit also extending over large parts of central Europe (Fig. 4b). They peak at −4 to −6 K around lags beyond 20 d, which corresponds well with the occurrence of the GL regime. Note that negative T2m' values in the composite for all SSWs are much weaker (see Fig. 4d). The associated retrogression of initial positive Z500' over the eastern North Atlantic to Greenland along with a strengthening of negative Z500' over the southeastern North Atlantic around lag 15–25 d is striking. Furthermore, GL is associated with warm anomalies over Greenland and eastern Canada." In the coming days we do see a second SSW. This time with a European Blocking. In EC46 at least we see this retrogression and strengthening of negative Z500' over the SE North Atlantic. Sciences rocks.

Double dip. No FW. MJO phase 7,8 on the long term. Northern blocking. Altough it can be somewhat to far away. We have to wait and see.

https://twitter.com/DrAHButler/status/1627008478467223557?cxt=HHwWisCz2ejlpZQtAAAA An intresting read by Amy Butler. Atmospheric Scientist at NOAA Chemical Sciences Laboratory, atmos dynamics/chemistry-climate, polar vortex expert, mother of two

Well at least the oper of EC is showing a European Blocking. As mentions earlier today, this seems to be important for the impact of the SSW.

Thanks Cold Winter Nights for the reminder of the Domeisen et al article. In my opinion this part is right now the most important: WCD - The role of North Atlantic–European weather regimes in the surface impact of sudden stratospheric warming events (copernicus.org) Figure 4Surface impact for SSWs with (a) Greenland blocking, (b) European blocking, and (c) cyclonic regimes around the SSW onset, as well as (d) for all SSWs. Shading indicates the composite 2 m temperature anomalies, with stippling (hatching) indicating significance at the 25 % (10 %) level. Blue contours correspond to geopotential height anomalies at 500 hPa in intervals of 50 gpm (geopotential meters). Negative values are dashed. The fields are averaged over 5 d between lags 0 and 25 d with respect to the SSW central date. Note the different scales for temperature in (a)–(c) and (d). The 2 m temperature anomalies are detrended and deseasonalized using 9-year and 21 d running mean filters. So we need to see European Blocking around the SSW onset. But we see right now cyclonic setting. Which doesn't deliver as we wished it would do. But... in the last days of February there will be a next dip. Then there will be European Blocking. So, I guess we have to wait a little longer, but according to this research and if there is European Blocking, there will be a long impact on the troposhere.

Yes Domeisen WCD - The role of North Atlantic–European weather regimes in the surface impact of sudden stratospheric warming events (copernicus.org) https://wcd.copernicus.org/articles/1/373/2020/

Great run by GFS6H. Some real cold air.

Thanks Nick. These intresting read can be found here: https://www.cpc.ncep.noaa.gov/products/predictions/long_range/fxus07.html

https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.3858 https://twitter.com/DrAHButler/status/1625228881832583205

GFS6h could be a reaction of the development in the stratosphere. Research shows that a negative NAO setting is very sensitive to the state of the stratosphere. https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.3280 Original post: https://community.netweather.tv/topic/98326-model-output-discussion-into-february/?do=findComment&comment=4805707

GFS6h could be a reaction of the development in the stratosphere. Research shows that a negative NAO setting is very sensitive to the state of the stratosphere. https://rmets.onlinelibrary.wiley.com/doi/abs/10.1002/qj.3280

https://charts.ecmwf.int/products/extended-anomaly-z500/overview/valid_time?base_time=202302130000&projection=opencharts_europe In march we see northern blocking.

A double SSW? Or SSW and FW?

Good luck to you Matt t. Wish you the best. https://rmets.onlinelibrary.wiley.com/doi/10.1002/qj.3017 or https://www.researchgate.net/publication/313547642_Predictability_of_downward_propagation_of_major_sudden_stratospheric_warmings_Downward_Propagation_of_SSWs Abstract Major sudden stratospheric warmings (SSWs) are striking phenomena of wintertime stratospheric circulation usually defined as a reversal of zonal mean circulation from westerlies to easterlies. SSWs often have significant impact on tropospheric circulation and cause anomalies in surface climate lasting for up to 2 months. For this reason, dynamics and predictability of SSW receive considerable attention. It is however well-known that not all SSWs cause significant, long-lasting impact on the troposphere. In order to explain differences in tropospheric impacts following SSWs, several reasons have been previously proposed, including differences in type of SSW (split or displacement), persistence of stratospheric anomalies, preconditioning of the tropospheric circulation, and whether or not SSW was accompanied by a planetary wave reflection in the stratosphere. Here we address the predictability of tropospheric impacts by SSWs by seeking early precursors of the impacts. We separate midwinter SSWs into two groups: those which are followed by significant, long-lasting impacts on the tropospheric circulation (defined in terms of anomalous Northern Annular Mode) and those not followed by significant anomalies in the annular mode. We show that SSWs characterised by a more negative Northern Annular Mode index in the lower stratosphere around 150 hPa and enhanced wave activity propagation to the stratosphere during the first few days following the central date have a larger probability of being followed by tropospheric impact, both in reanalyses and in climate model runs. These anomalies play a more important role in the subsequent downward propagation of the signal to the troposphere than the type of SSW: whether it is a split or a displacement, or absorptive or reflective SSW. We propose that using these anomalies as precursors of tropospheric impacts of SSW can enhance climate predictability. --------------- Right now we see positive AO in the lower stratopshere around 150 hPa by next week. So, according to this study I guess there is less chance for a tropsheric impact. Sorry to say.

This one is important as well https://twitter.com/SimonLeeWx/status/1582372470027272192

https://digital.csic.es/bitstream/10261/185753/1/No robust evidence_Ayarzaguena.pdf

In 2018 the MJO was extreme. This time probably not.

At the long term it always shows phase 0 (average).

I assume this will be phase 6,7.

Please keep in mind by that time we can/might enjoy the impact of MJO phase 6 perhaps 7.

ECMWF | Charts A SSW seems a realistic possibility.

2018 was a combination between a very impressive MJO phase 6,7 and SSW.

GFS underestimates the cold.

Indeed, what an exceptional anti-cyclone. Record for the Netherlands is 1050 hPa. Article by Burt. The Highest of the Highs … Extremes of barometric pressure in the British Isles, Part 2 – the most intense anticyclones - Burt - 2007 - Weather - Wiley Online Library The all-time UK record is 1053.6 mb recorded at Aberdeen Observatory on January 31, 1902. https://rmets.onlinelibrary.wiley.com/doi/10.1002/wea.35