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sryanbruen · 14-11-2019, 13:05

The November update of the ECM is now suggesting a weaker than average stratospheric polar vortex at 10hPa during December 2019 contrast to last month's update. However, the Glosea5 is less confident on this with quite a high spread especially in January. It's important to note that the Glosea5 has a better verification record than the seasonal ECM but at the end of the day, they're long range models so prone to huge changes.

https://twitter.com/SimonLeeWx/statu...62609595768833

Yesterday's GFS backed away significantly from the SPV getting disturbed with +AO filtering down through the atmosphere in FI whilst still forecasting quite a weakening in the zonal mean zonal winds at 60N 10hPa. The ECM showed similar but actually also showed a strengthening again at the end of FI.

Very confusing picture.

Villain · 18-11-2019, 09:03

End of GFS run this morning

Villain · 18-11-2019, 13:36

Winds forecast today, starting to see what could be the start of some foundations being poured?

**Gonzo** · 18-11-2019, 17:05

It's certainly early to be seeing one of these, lets see how it plays out, last winter it didn't play in our favour.

hatrickpatrick · 18-11-2019, 20:37

Someone with more knowledge of the modelling data might be able to shed some light on this: A poster over at NetWeather mentioned that since November 15th, the GFS and its ensembles have been running without one of its datasets, the Ozone Monitoring Instrument (OMI) and that this can result in a warm bias in the strat charts. That poster reckoned that the warming we're seeing was still most likely legit, but that it might appear stronger on the models runs until the OMI is reinstated.

I've had a quick look around online and can't find any information on this, or how soon this data might be reintroduced into the GFS, anyone have any further info?

aidanodr · 20-11-2019, 16:57

UK weather forecast: Terrifying map shows COLLAPSED polar vortex freezing UK in December - DE EXPREZZZZZ

highdef · 20-11-2019, 23:32

Quote:

Originally Posted by aidanodr

UK weather forecast: Terrifying map shows COLLAPSED polar vortex freezing UK in December - DE EXPREZZZZZ

Warning..... This link is to a ****ty British tabloid newspaper well known for over hyping the weather.

Oneiric 3 · 21-11-2019, 11:20

Quote:

Originally Posted by aidanodr

UK weather forecast: Terrifying map shows COLLAPSED polar vortex freezing UK in December - DE EXPREZZZZZ

hatrickpatrick · 21-11-2019, 19:45

Quote:

Originally Posted by highdef

Warning..... This link is to a ****ty British tabloid newspaper well known for over hyping the weather.

They over hype everything. I've been waiting ten years for the imminent apocalyptic Yellowstone eruption they were talking about back in 2008

Villain · 22-11-2019, 13:58

0c be warm

Villain · 25-11-2019, 08:34

Latest GFS

BLIZZARD7 · 25-11-2019, 13:07

Looking good for a PV disruption mid December me thinks... Could be timed perfectly as the trop/pv reconnects just in time to be disrupted.

Gaoth Laidir · 27-11-2019, 18:10

The ECMWF had a big seminar on the stratosphere recently.

https://www.ecmwf.int/en/about/media...sphere-weather

Quote:

There are also some known issues with ECMWF’s model at the sub-seasonal to seasonal range.

“There are stratospheric temperature biases in the model, and the connection between the troposphere and the stratosphere becomes too weak in the northern hemisphere beyond a month into the forecast,” says ECMWF scientist Tim Stockdale, who co-organised the event.

Tim Stockdale talked about a new approach to linear ozone modelling.

Recommendations made at the workshop include improved modelling of gravity waves (atmospheric waves produced, for example, by airflow over mountains) and of the mesosphere (the atmospheric layer above the stratosphere).

Tim points out that a snap poll among the attending scientists showed little consensus, and a great deal of uncertainty, about the correct seasonal forecast for this winter.

“It illustrates the fact that seasonal winter forecasts for Europe are difficult. It means that we have our work cut out to improve our models, and the findings presented at this workshop will help us to move forward.”

**Gonzo** · 27-11-2019, 21:11

not what we want to see seeing going into December.

nacho libre · 03-12-2019, 18:27

Judah Cohen seems to suggest there maybe a Canadian warming going on.

"But since late November the Ural/Scandinavian blocking has been replaced by much lower pressures/heights (probably in part to the migration of the PV center to that region), a pattern less favorable for disrupting the PV.

The models in general have been less aggressive in disrupting the PV and probably a major mid-winter warming (reversal of the zonal mean zonal wind from westerly or positive to easterly or negative at 60°N and 10 hPa) is less likely than I previously thought. All models predict a minor warming with ridging near Alaska and Northern Canada and the PV near and along the north slope of Eurasia. This does resemble what is referred to as a Canadian warming. This rarely results in a major warming but I do believe can be a precursor to a more significant warming later on. "

There was i believe a Canadian warming in some notable winters of the past

25-11-2019, 13:07	#27
BLIZZARD7 Registered User Join Date: Dec 2010 Posts: 1,777 Adverts \| Friends	Looking good for a PV disruption mid December me thinks... Could be timed perfectly as the trop/pv reconnects just in time to be disrupted. Last edited by BLIZZARD7; 25-11-2019 at 13:14.

27-11-2019, 21:11	#29
Gonzo Moderator Join Date: Aug 1999 Posts: 12,355 Adverts \| Friends Mod: Weather, ZTest	not what we want to see seeing going into December. Last edited by Gonzo; 27-11-2019 at 21:14. Reason: spelling

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14-11-2019, 13:05	#16
sryanbruen Registered User Join Date: Aug 2015 Posts: 11,017 Adverts \| Friends	The November update of the ECM is now suggesting a weaker than average stratospheric polar vortex at 10hPa during December 2019 contrast to last month's update. However, the Glosea5 is less confident on this with quite a high spread especially in January. It's important to note that the Glosea5 has a better verification record than the seasonal ECM but at the end of the day, they're long range models so prone to huge changes. https://twitter.com/SimonLeeWx/statu...62609595768833 Yesterday's GFS backed away significantly from the SPV getting disturbed with +AO filtering down through the atmosphere in FI whilst still forecasting quite a weakening in the zonal mean zonal winds at 60N 10hPa. The ECM showed similar but actually also showed a strengthening again at the end of FI. Very confusing picture.

18-11-2019, 09:03	#17
Villain Registered User Join Date: Nov 2002 Posts: 15,323 Adverts \| Friends	End of GFS run this morning

18-11-2019, 13:36	#18
Villain Registered User Join Date: Nov 2002 Posts: 15,323 Adverts \| Friends	Winds forecast today, starting to see what could be the start of some foundations being poured?

18-11-2019, 17:05	#19
Gonzo Moderator Join Date: Aug 1999 Posts: 12,355 Adverts \| Friends Mod: Weather, ZTest	It's certainly early to be seeing one of these, lets see how it plays out, last winter it didn't play in our favour.

18-11-2019, 20:37	#20
hatrickpatrick Registered User Join Date: Jun 2005 Posts: 16,937 Adverts \| Friends	Someone with more knowledge of the modelling data might be able to shed some light on this: A poster over at NetWeather mentioned that since November 15th, the GFS and its ensembles have been running without one of its datasets, the Ozone Monitoring Instrument (OMI) and that this can result in a warm bias in the strat charts. That poster reckoned that the warming we're seeing was still most likely legit, but that it might appear stronger on the models runs until the OMI is reinstated. I've had a quick look around online and can't find any information on this, or how soon this data might be reintroduced into the GFS, anyone have any further info?

20-11-2019, 16:57	#21
aidanodr Registered User Join Date: Apr 2006 Posts: 551 Adverts \| Friends	UK weather forecast: Terrifying map shows COLLAPSED polar vortex freezing UK in December - DE EXPREZZZZZ

22-11-2019, 13:58	#25
Villain Registered User Join Date: Nov 2002 Posts: 15,323 Adverts \| Friends	0c be warm

25-11-2019, 08:34	#26
Villain Registered User Join Date: Nov 2002 Posts: 15,323 Adverts \| Friends	Latest GFS

03-12-2019, 18:27	#30
nacho libre Registered User Join Date: Aug 2006 Posts: 13,059 Adverts \| Friends	Judah Cohen seems to suggest there maybe a Canadian warming going on. "But since late November the Ural/Scandinavian blocking has been replaced by much lower pressures/heights (probably in part to the migration of the PV center to that region), a pattern less favorable for disrupting the PV. The models in general have been less aggressive in disrupting the PV and probably a major mid-winter warming (reversal of the zonal mean zonal wind from westerly or positive to easterly or negative at 60°N and 10 hPa) is less likely than I previously thought. All models predict a minor warming with ridging near Alaska and Northern Canada and the PV near and along the north slope of Eurasia. This does resemble what is referred to as a Canadian warming. This rarely results in a major warming but I do believe can be a precursor to a more significant warming later on. " There was i believe a Canadian warming in some notable winters of the past