[Moans, ramps and banter]

It is good to see the quality of the posts in the chasing cold thread is rising exponentially as noted with a recent offering of "corker inbound" 

[Model banter and emotions]

The latest longer range output is pretty much in agreement with the expected movement of the tpv lobe to NE Europe. Lovely jubbly

500 hPa height and 2m temp Weekly mean anomalies and little precipitation

[Moans, ramps and banter]

Toasty from the gfs........always the model of choice

[Model Output Discussion - Colder but how cold and for how long?]

1 hour ago, AO- said:

I disagree that Scandinavian hights are the holy Grail to look for atm. Yes, eventually for enduring cold, the Scandinavian block is what we want, but 2012 dids not have a Scandinavian block when winter set in. It started with a block over Kazachstan, ending up with a Northwest Russian block. A southeasterly van be very cold with the right setup. And writing off something that is in far FI, is just ridiculous. The Scandinavian block is still in the EPS (albeit minimal with 4 members, but that number is pretty constant), just not in the operational. Since when do we take one operational at day 11 seriously? 

In my experience, which I admit is very limited, whenever they are indicating severe cold and snow. Otherwise discard without further thought. 

[Model Output Discussion - Colder but how cold and for how long?]

The rapid cyclogenesis on this evening's gfs worth a mention as the low tracks NE south of Iceland down  to 924mb by 00 Saturday

[Model Output Discussion - Into 2024]

5 minutes ago, Mcconnor8 said:

Looks to be a rogue ECM run regarding a shortwave heading North from the Atlantic low at T+120, every other model doesn't have it, or like the GFS makes much less of it, ensemble pack of ECM also doesn't really so looking good currently.

The gfs temp panels through the 10-15 period show an increasing number of members along the same limes as the ecm. Oh suffering succotash

[Moans, ramps and banter]

Fascinating discussion over in the mod thread, it will be repeated again and again if you have missed it this time around, on the length and severity of the upcoming cold spell. Mind its not due to start for another ten days 

[Model Output Discussion - Into 2024]

10 minutes ago, blizzard81 said:

Would you be kind enough to post the 360hr chart please?

It warms the cockles 

[Winter 2023/24 Chat and Discussion]

The good news from the gfs this evening is that the Arctic air is slowly being shunted east. I understand defibrillators are on standby

[Winter 2023/24 Chat and Discussion]

Looking at the latest updates there is every chance the Dafs will be early down here this year,

[Model Output Discussion - Into Winter]

2 minutes ago, Nick F said:

It will lift the doom and gloom for 6 hours, unless the pub run follows suit with a similar stonker of a northerly, then we can wait for a reality check in the morning 

Maybe two hours if the ecm doesn't follow and drop the lobe of the vortex down the eastern US

[Winter 2023/24 Chat and Discussion]

Interesting forecast sounding for 00 on the 19th

[Teleconnections - Interactions and Impact]

 

[Winter 2023/24 Chat and Discussion]

Need to give the barby a quick dust before the weekend 

[Model discussion highlights]

24 minutes ago, Ruzzi said:

I think you'll probably find that calling wet and mild until the end of the year when it's far outside even the depths of FI on the models is more of a 'mugs game' 

Essentially what you've said is: ignore background signals, have a look at what you see in the models, take that as gospel and run with the thought ls that it'll continue beyond the forecast period exactly the same. 

Nothing can be taken as gospel just now, not when the extent of the MJO amplification can't be pinned down yet with conflicting forecasts. There's no doubt that whatever verifies with the MJO in terms of amplification will have a knock on effect. 

MJO aside, it's again subjective to location, in terms of how wet and how mild the near term gets but I'd not be hanging my hat on it continuing until the end of the year, just as much as I'd not be hanging on a colder outlook. There's plenty water to pass under the bridge in the next week or so. 

I don't think that is what he is saying. But in any case  it is not that easy to evaluate the probable influence of the the forecast background signals on the Atlantic and European weather as some on here make out. But having said that they should always be taken into account along with  a keen scrutiny  of the model outputs.

Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4974204

[Model Output Discussion - Into Winter]

24 minutes ago, Ruzzi said:

I think you'll probably find that calling wet and mild until the end of the year when it's far outside even the depths of FI on the models is more of a 'mugs game' 

Essentially what you've said is: ignore background signals, have a look at what you see in the models, take that as gospel and run with the thought ls that it'll continue beyond the forecast period exactly the same. 

Nothing can be taken as gospel just now, not when the extent of the MJO amplification can't be pinned down yet with conflicting forecasts. There's no doubt that whatever verifies with the MJO in terms of amplification will have a knock on effect. 

MJO aside, it's again subjective to location, in terms of how wet and how mild the near term gets but I'd not be hanging my hat on it continuing until the end of the year, just as much as I'd not be hanging on a colder outlook. There's plenty water to pass under the bridge in the next week or so. 

I don't think that is what he is saying. But in any case  it is not that easy to evaluate the probable influence of the the forecast background signals on the Atlantic and European weather as some on here make out. But having said that they should always be taken into account along with  a keen scrutiny  of the model outputs.

[Model Output Discussion - Into Winter]

16 minutes ago, Allseasons-Si said:

The gfs has a better handle on Atlantic heights than any other model,...the ECM will play catch up with this over the coming days

meanwhile up top,...the control has a split at 10 hpa and the mean has a warming too.

we do have a cooler spell of weather midweek next week then a slight warm up before turning seasonal for the Christmas period but that is to be concluded for some time i would think

so plenty to keep tabs on.

Could you post a link to the research that will corroborate that comment Ta

[Model Output Discussion - Into Winter]

Just now, January Snowstorm said:

Anything after 240hrs is irrelevant!! The key charts are 192 to 240hrs. That's where you look for improvement and try to see do other models pick up this trend. I'm unsure why the gfs runs beyond 240, its meaningless

Right, and the key to the gfs is the arctic plunge down eastern NA that amplifies the ridge into Greenland with the resultant CAA into Europe. Place your bets on the ecm doing the same but I know where my money is going

[Winter 2023/24 Chat and Discussion]

Quote of the day in the mod thread.

"We can't cherry pick what we want to see , this is the model thread"

 I actually came over quite faint reading it. 

[Comparing Sea Surface Temperatures in June-July-August 2022 to June-July-August 2023]

Ocean surface temperatures set records during the Northern Hemisphere summer of 2023. This comparison shows how much warmer the ocean was in 2023 compared to the previous summer

Introduction

In 2023, many factors have contributed to remarkably high temperatures on land and in the oceans. One of these factors was the development of El Niño conditions in the tropical Pacific Ocean, as well as the corresponding (but not as well known) tropical Atlantic Ocean El Niño. However, this was not the only factor, nor was it the only place that sea surface temperatures (SSTs) were notably warmer than normal. Temperatures in the Mediterranean Sea, off the coast of Florida, and in the North Atlantic Ocean also made the news, and these elevated temperatures were implicated in significant weather events, particularly extreme rains and intense tropical cyclones.

Many maps of SST show anomalies, which are the temperatures compared to a baseline mean temperature averaged over many years (commonly 30 years). While this common depiction is very useful, it is not unusual for temperatures to be warm in the summer (in this case, summer in the Northern Hemisphere). So, in this Data-in-Action article, the NASA visualization tools Giovanni and Panoply are used to compare SSTs averaged over the months of June, July, and August in 2022 and 2023.

https://disc.gsfc.nasa.gov/information/data-in-action?title=Comparing Sea Surface Temperatures in June-July-August 2022 to June-July-August 2023&utm_source=newsletter&utm_medium=email&utm_campaign=earthdata-discovery-122023

[Winter 2023/24 Chat and Discussion]

Oh God they are talking about the winter of 62-3 again, and again, and again, and again.

[The World's Glaciers]

Showcasing the death of the world’s glaciers

By Audrey Payne

Among the mountains of evidence that climate change is warming Earth faster than any other point in recorded history is the fact that most glaciers around the world are shrinking or disappearing. Melting glaciers and ice sheets are already the biggest contributors to global sea level rise, and according to the World Glacier Monitoring Service, ice loss rates have increased each decade since 1970. Yet, of the approximately 200,000 glaciers in the world currently, no database exists to identify which glaciers have disappeared, and when. The Global Land Ice Measurements from Space (GLIMS) initiative, an international project designed to monitor the world's glaciers primarily using data from optical satellite instruments, aims to change that.

“Glaciers are indicators of climate change because they grow and shrink on longer timescales than rapidly changing weather, so they give a clearer signal about climate,” said Bruce Raup, a senior associate scientist at the National Snow and Ice Data Center (NSIDC) and director of the GLIMS initiative. “We know that glaciers are disappearing, but we’ve had no way to show that to people. So, we are making an effort to document glaciers that have disappeared and approximately when they disappeared.”

https://nsidc.org/news-analyses/news-stories/showcasing-death-worlds-glaciers?utm_source=newsletter&utm_medium=email&utm_campaign=earthdata-discovery-122023

[Winter 2023/24 Chat and Discussion]

A lot of comments again this morning in the mod thread about 'good or bad outputs' which are subjective and totally meaningless to ordinary mortals. They merely reflect the mindset of the thread.

[Model Output Discussion - Into Winter]

7 minutes ago, Derecho said:

Of course interpreting the data at face value like that there would be a correlation. Though at this time of the year that relationship breaks down under a period of calm conditions. I think that is what you are alluding to here at least.

In fact at any time of the relationship is fragile if anything impacts the lapse rate such CAA within the layer for example. I would have thought you always need to take great care evaluating  surface temps from the 850s unless other info is also available

[Autumn & Winter 2023---2024 Stratospheric Polar Vortex. Events, Analysis, Discussions AND Outlooks]

How do different pathways connect the stratospheric polar vortex to its tropospheric precursors?

Abstract

Processes involving troposphere–stratosphere coupling have been identified as important contributors to an improved subseasonal to seasonal prediction in the mid-latitudes. However, atmosphere models still struggle to accurately predict stratospheric extreme events. Based on a novel approach in this study, we use ERA5 reanalysis data and ensemble simulations with the ICOsahedral Non-hydrostatic atmospheric model (ICON) to investigate tropospheric precursor patterns, localised troposphere–stratosphere coupling mechanisms, and the involved timescales of these processes in the Northern Hemisphere extended winter. We identify two precursor regions: mean sea level pressure in the Ural region is negatively correlated with the strength of the stratospheric polar vortex for the following 5–55 d with a maximum at 25–45 d, and the pressure in the extended Aleutian region is positively correlated with the strength of the stratospheric polar vortex the following 10–50 d with a maximum at 20–30 d. A simple precursor index based on the mean pressure difference of these two regions is very strongly linked to the strength of the stratospheric polar vortex in the following month. The pathways connecting these two regions to the strength of the stratospheric polar vortex, however, differ from one another. Whereas a vortex weakening can be connected to prior increased vertical planetary wave forcing due to high-pressure anomalies in the Ural region, the pathway for the extended Aleutian region is less straightforward. A low-pressure anomaly in this region can trigger a Pacific–North American-related (PNA-related) pattern, leading to geopotential anomalies of the opposite sign in the mid-troposphere over central North America. This positive geopotential anomaly travels upward and westward in time, directly penetrating into the stratosphere and thereby strengthening the stratospheric Aleutian High, a pattern linked to the displacement towards Eurasia and subsequent weakening of the stratospheric polar vortex. Overall, this study emphasises the importance of the time-resolved and zonally resolved picture for an in-depth understanding of troposphere–stratosphere coupling mechanisms. Additionally, it demonstrates that these coupling mechanisms are realistically reproduced by the global atmosphere model ICON.

https://wcd.copernicus.org/articles/4/1071/2023/