Vikos

Adding +252h 850ht

Would agree if we where somewhere around mid-to-end of February, but hey, it's still (begin) of January. We had a (by now in detailted outcome unpredictable) SSWE with great NH-patterns wich show more cold then mild outcomes, even without a PV-Split, wich is to come by the 3rd decade of January if more minor warmings (like predicted) attack it. Regarding cold to the Northeastern, Sibiria is facing record colds...

U never know...

EC 00z Scenarios

First, it goes way down, then, if we don't see a final warming, maybe up...

Just dropping it... Para

Fresh EC 12z Scenarios, beginning with +72 and 3 Clusters! 6 clusters already in +144h! This 12z is messed up!

Greenland high, Greenland high... better use WZ charts! Meteociel isn't always too acuarte...

Hey folks, my package from Wish! just arrived

This rigde building up over pacific is another stepstone to a possible PV-Split in the 3rd decade

Thank you BA for pointing out what I was all about GFS has the same on schedule (still 00z) The polar vortex has formed a huge main vortex over Eurasia with a center over northern Siberia and a smaller partial vortex over northern Canada (polar vortex split), a strong icy trough lies over Central Europe. Between the high pressure bridge over Greenland and the main vortex over Eurasia, Arctic air masses flow from the Arctic directly to Europe

What if EC op is an outlier and has no support from its EPS/Scenarios?

It’s getting ridiculous in here right now, just over one for some not so favourable run, disregarding the overall patterns we have. Childish behaviour, I’m sorry to say...

That’s because some here are hyping every run too much. that shows maximum cold... and forgetting that ALL models are swinging like crazy even in short range. Let the 3rd warming develop and kill the PV first, then watch the outcome...

Wait until the 3. warming splits (terminates) the PV... that will be an epic end of January...

This I don't understand, the comparison off "middle" and "full" runs is just... GFS data usage Source: https://www.metcheck.com/WEATHER/gfs_gdas_observation_amount_quality.asp

Our national Weather Service in Germany (DWD) has it as the "Topic of the day" today, more on this topic to follow this week. Sudden Stratospheric Warming, Now What? On 05./06.01.2021 a so called "major sudden stratospheric warming" (SSW) took place. What is behind it and how it came about is to be highlighted in today's topic. The potential effects on the medium and long-term forecast should also be briefly mentioned. Sudden stratospheric warming occurs statistically every two years in the northern hemisphere winter. By definition, one speaks of a "major sudden stratospheric warming" or a marked sudden stratospheric warming if the westerly wind (zonally averaged, i.e. on a degree of latitude, here 60 degrees N circumpolar) in 10 hPa (at a height of around 31 km) turns completely to east wind, i.e. reverses, in addition to a sharp rise in temperature in the upper stratosphere above the North Pole. A "minor stratospheric warming" (weaker event) is also associated with a marked increase in temperature in the polar upper stratosphere, but not with a complete wind reversal. The background to this definition is a marked weakening of the stratospheric polar vortex, which leads to a large-scale change in tropospheric circulation patterns as well. How did this event come about? Given the starting conditions, the question does not seem out of place. We have had a veritable "La Nina" event (cold phase of the ENSO circulation (see link weather dictionary) in the central and eastern equatorial Pacific) for some time now. In the specialist literature one can read that with "La Nina" events the stratospheric polar vortex is normally not disturbed as much as with "El Nino" events. The background here is the reduced wave flow (heat and momentum flows) into or in the stratosphere at "La Nina". "La Nina" is also related to the Pacific circulation, i.e. roughly speaking high air pressure over the North Pacific, which in turn weakens the more or less persistent Aleutian low. So much for the theory. What we experienced from the middle / end of December 2020, in addition to sea surface temperatures that were significantly too high in the western and northwestern North Pacific, was an unusually strong high with icy temperatures over eastern Siberia / Mongolia. This explosive mixture of temperature contrasts then led to a significant strengthening of the Aleutian low (see details in the upcoming topic of the day on January 14, 2021 by Helge Tuschy). A similarly strong Aleutian low can usually be found in "El Nino" years. On its front side, strong heat flows are transferred meridionally and especially vertically into the stratosphere. However, this coupling is only possible in the winter half-year, because then westerly winds prevail in the troposphere as well as in the stratosphere of the middle and high latitudes and the wave flows can thus interfere with one another (overlap). In any case, this leads to a weakening of the stratospheric polar vortex (SPV), since wave energy is also converted into thermal energy (i.e. the basically "cold" polar vortex is heated). In our case, stratospheric warming creates an area of high air pressure in the stratosphere (on the Pacific side). Ideally, the SPV is also disturbed from the Atlantic side. Then there is the classic "split" of the SPV. This year's SSW is more likely to be a hybrid between "displacement" of the SPV from the Pacific and a split, especially since another "warming" with wind reversal (60 degrees N, 10 hPa) is forecast for the middle of the month. All in all, this year's event looks like a lasting disruption or weakening of the SPV, which brings us to the effects that await us. Only briefly will be discussed here, in the TdT of January 14th, 2021 it will be more specific. In any case, the disturbance dynamically spreads over time from the stratosphere to the troposphere (classically characterized by high air pressure over the Arctic). This is accompanied by a clearly negative index of the Arctic and North Atlantic Oscillation (AO and NAO), whereby the reversal of the wind and increasingly meridional flow patterns mean that Arctic air masses penetrate far south. The specialist literature describes Eurasia as a preferred region over North America. In principle, SSW events can now be predicted relatively well using the weather models (even in the medium term, since the models calculate relatively well up to the stratosphere). However, there are still problems with the dynamic coupling of the stratosphere and the troposphere on the one hand and with the assignment to possible tropospheric flow patterns on the other. The latter show quite a variability. In principle, SSW events can now be predicted relatively well using the weather models (even in the medium term, since the models calculate relatively well up to the stratosphere). However, there are still problems with the dynamic coupling of the stratosphere and the troposphere on the one hand and with the assignment to possible tropospheric flow patterns on the other. The latter show quite a variability. Here, the statistics could help considerably in the future with a better and more systematic recording of events. Another problem is the chronological classification of the effects, as the tropospheric patterns usually only change after about 10 to 15 days after the event. Last but not least, it should be mentioned that the impact of a SSW event on the troposphere can last for two months or more. We almost came to the seasonal weather forecast. Source: Wetter und Klima - Deutscher Wetterdienst - Thema des Tages - Plötzliche Stratosphärenerwärmung, was nun? WWW.DWD.DE Am 05./06.01.2021 fand ein so genanntes "major sudden stratospheric warming statt"(SSW). Was sich dahinter verbirgt und wie es dazu kam, soll im heutigen Tagesthema beleuchtet werden. Ebenso sollen die... Translation by google.com

Finally CFS is on tracks!

According this 150hpa chart, gates for significant artic cold air is given. (outbreak outbreak)

Again, those EC Scenarios are

Excatly! In synopctics, you compare 12z to 12z and 00z to 00z... !

Still some days to get the cold even to your island. Models are swinging, don't get traped and depressed over some "not-so-cold" runs. 18z will be a killer again, 00z hangover and so on. +14hh, everything after is didi-land

I am not sure, I can be something different. I read about it some time (years) ago. Can also be the density of data after that timemark. But I know that there is something after +240h in the GFS modelling. I will search for it and PN you