sebastiaan1973

Glosea5.

Seems to be a winter with a strong nothern Pacific high. Positive NAO. So Western-Europe will experience a mild winter. At least according to EC-seasonal.

http://twitter.com/SimonLeeWx/status/1324736557597773824 I'm excited to add a new (experimental) forecast product to my website: GEFS 35-day forecasts of North American wintertime weather regimes! Regimes can be a useful tool for subseasonal forecasting. Check it out Tweet by Simon Lee from the UK.

https://agupubs.onlinelibrary.wiley.com/doi/epdf/10.1029/2019GL085592 The impact of the Arctic stratospheric polar vortex on persistent weather regimes over North America is so far underexplored. Here we show the relationship between four wintertime North American weather regimes and the stratospheric vortex strength using reanalysis data. We find that the strength of the vortex significantly affects the behavior of the regimes. While a regime associated with Greenland blocking is strongly favored following weak vortex events, it is not the primary regime associated with a widespread, elevated risk of extreme cold in North America. Instead, we find that the regime most strongly associated with widespread extremely cold weather does not show a strong dependency on the strength of the lower stratospheric zonal mean zonal winds. We also suggest that stratospheric vortex morphology may be particularly important for cold air outbreaks during this regime

Is this an indication for a east based La Nina?

Thanks Benchmark. Intresting read. In your blog, you speak about a mixed La Nina http://easternmassweather.blogspot.com/2020/10/mixed-signals-regarding-enso-for-winter.html in 1970-1971 1999-2000 2007-2008 All of these years had a SSW.

Very strong La Nina -2c. Is this realistic?

Hi guys, first of all thanks for sharing all your thoughts from the otherside of the Atlantic Ocean. I'm having fun reading your intelligent readings. Since the 8th of october a lot more of ECMWF is available. You can take a look over here https://apps.ecmwf.int/webapps/opencharts/products/extended-anomaly-mslp?base_time=202010080000&projection=opencharts_global&valid_time=202011090000 for the weeklies. Or https://apps.ecmwf.int/webapps/opencharts/?facets={"Type"%3A[]%2C"Range"%3A[]%2C"Product type"%3A["High resolution forecast (HRES)"]%2C"Parameters"%3A["Precipitation"%2C"Snow"%2C"Surface characteristics"%2C"Temperature"%2C"Wind"]}

http://www.nature.com/articles/s41558-019-0551-4.epdf?author_access_token=lev7cCLvJaqZgqEL2fkrCtRgN0jAjWel9jnR3ZoTv0OkPw7OWz-ctumf1Sllaa-sNqBW8kixcwl-ojSoyKUmUfvHbXmZ3llXRmZN-HO_pmKRWEHLwCuZqZkuv4bolog-ehQV4R4jg8i93P7ntZX4_w%3D%3D Observations show that reduced regional sea-ice cover is coincident with cold mid-latitude winters on interannual timescales. However, it remains unclear whether these observed links are causal, and model experiments suggest that they might not be. Here we apply two independent approaches to infer causality from observations and climate models and to reconcile these sources of data. Models capture the observed correlations between reduced sea ice and cold mid-latitude winters, but only when reduced sea ice coincides with anomalous heat transfer from the atmosphere to the ocean, implying that the atmosphere is driving the loss. Causal inference from the physics-based approach is corroborated by a lead–lag analysis, showing that circulation-driven temperature anomalies precede, but do not follow, reduced sea ice. Furthermore, no mid-latitude cooling is found in modelling experiments with imposed future sea-ice loss. Our results show robust support for anomalous atmospheric circulation simultaneously driving cold mid-latitude winters and mild Arctic conditions, and reduced sea ice having a minimal influence on severe mid-latitude winters.

Thanks 40/70 Benchmark for an intresting read.