Winter Approaching: Forecast and Model Discussion Commentary

[TSNWK]

Yuck.. chilly rain and wind.. turning wintry for a goat up a mountain in Scotland 

 

 

[TSNWK]

Interesting vortex location 

[AO-]

 TSNWK

Good Morning,

Heading in the wrong direction already at 144. Guess it is an outlier

Edited December 6, 2024 by AO-

[RJBingham]

No white Christmas this year, around here anyway.

Next question, can we go all of 2024 without a single flake?

[Kirkcaldy Weather]

I have wanted to address certain things for a long time so lets begin with the plethora of recent posts regarding the MJO including those I have selected above  

There are quite a few important and key aspects within the MJO most of which have hopefully been gleamed by those members who are regular followers / readers of my posts as the MJO is one of the biggest aspects of my posts / work for many years now. I will try to discuss many of the factors of the MJO in this post. The MJO is made up of 2 main Velocities at 200mb these being Below and Above Average Velocities which equate to Below and Above Average Pressure - Higher and Lower than Average Pressure. Something I have discovered within the past year following a lot of work is something which can finally dismiss any further comments regarding the so called "COD - Circle Of Death" firstly I'd like to refer back to my detailed post from July 2023 which covered the MJO 

I will re copy some of the most important parts but very much worth re reading for all members  

"Next @JayAlmeida stating "So stuck in circle of doom = summer over" this might be perceived as a question or another annoyance which is the 'summer is over' statements I'll address this separately in a short while. IF it was a question I answered and spoke of how this terminology/mindset is incorrect and overused when MJO forecasts go in the O. All this part of the MJO phase spectrum means is lower amplitude equating to adjacent phase(s) because the MJO has an always active state at differentiating amplitudes."

"The MJO is one of the biggest contributing teleconnections in the development of  weather patterns globally, I think that's another massive problem with the members who only say 'summers over' 'groundhog day' 'never changing setup' etc and 99% they never provide ANY charts or relevant info. Thinking the patterns over a broadscale will shift at the drop of a hat ain't gonna happen,with a slow pace of MJO of late, an increasingly imprinting Ninò an emerging MJO cycle of SUPER importance tied to Ninò peak C and hurricane developments in the balance the atmosphere requires time to fully process these developments and thus equal patience remains a requirement in regard to the process of trough and unsettled weather for the UK and Scandinavia in particular toward that of a high which I've spoke about."

Now onto the discovery I have made which is that the centre of the MJO forecast charts shown as low amplitude in the excellent image above is actually the equator and what I have noted is that when the MJO enters this centre circle it is actually when the main part of the MJO's Below Average 200mb Velocities are located at and south of the equator ie within the Southern Hemisphere. Another very important aspect to note is that the forecast charts are only showing where the MJO's Below Average 200mb Velocities are located and NOT where the Above Average 200mb Velocities are located. 

Looking into some of the main impacts via the MJO's recent progression which include Significant Rainfall impacts as the Below Average 200mb Velocities moved across Australia which is the reason for the wet episodes on I'm A Celebrity Get Me Out Of Here 

 

I'm A Celebrity shares update after extreme floods almost forced show off air

METRO.CO.UK

---

The show was thrown into chaos, with Ant and Dec's live links almost scrapped.

 

Ant McPartlin confirms I'm A Celebrity has been rocked by 'touch-and-go' incident

WWW.HELLOMAGAZINE.COM

---

Torrential rain has wreaked havoc on the set

I'm A Celeb in chaos and almost forced off air amid floods and worst rain in show's history - OK! Magazine

WWW.OK.CO.UK

---

I'm A Celebrity... Get Me Out Of Here! was nearly forced off the air due to the rain and floods in camp, with Ant and Dec forced to reveal that parts of the set had been destroyed

 

As discussed in my post on November 4th

 

"CFS keen on a very strong MJO Event - Below Average 200mb Velocities as they progress across The Indian Ocean"

Credit Japanese Meteorological Website Phase and amplitude monitor (last 40-day)

MJO

DS.DATA.JMA.GO.JP

As the MJO's Below Average 200mb Velocities progressed across The Indian Ocean this lead to the development of Cyclone Fengal

 

As we can see via the MJO Velocities the main part of the Below Average Velocities are in the Indo Pacific > Maritimes including Australia and the West / Northwest Pacific 

The MJO Velocities are due to convection including the development of Thunderstorms with Warmer / Above Average Sea Surface Temperatures causing more frequent MJO activity and Cooler / Below Average Temperatures causing less frequent MJO activity ie the Above Average 200mb Velocities which lead to less / no convection with Above Average / Higher Pressure, We can see this is a big factor in exactly where the strongest MJO convection in the above charts is occurring with the higher Sea Surface Temperatures particularly West Northwest of Australia > The Indo-Pacific Warm Pool > The Maritimes 

Thunderstorms are a key element in Cyclonic - Tropical Storm - Hurricane developments with the next highly favourable area for potential Cyclonic developments West Northwest of Australia which is an excellent match to the Tropical Cyclone Heat Potential data via Cyclonicwx

 

http://www.bom.gov.au/climate/enso/#tabs=Tropics&tropics=About

Thanks for reading. KW 

[Beanz]

 Kirkcaldy Weather you need to make your posts more simple to navigate and include less links which are unnecessary and only make the whole thing so difficult to read and understand, that some people probably don’t bother reading it.    

[stewfox]

 Beanz yes it's a shame as it probably has some interesting content in their but far too many attachments . Now get me out of here.

[mountain shadow]

 RJBingham I actually think there is a chance we get lucky from a potent Northerly toppler.

 

[RJBingham]

 mountain shadow Anything is possible, I've never seen snow on Christmas day, be nice to see it at least once  

[Dennis]

KMA

[AO-]

To reply on my previous post; EC operational is an outlier on the mild side. But the EPS downgraded as well on the midterm as well as the long term. 

Edited December 6, 2024 by AO-

[Jacob]

GEFS has several members with lower 850s in FI

[Dennis]

be safe UK friends 

[bluearmy]

Gfs 00z op is (afaik) the first op this season to reverse the zonal flow in the strat.  Right at the top and down to around 3 hpa/80N

this is how full on reversals usually begin to show - its defintiely what we’d hope to see based on the direction of travel. Consistency please and down towards 60N! 

[StretfordEnd1996]

Morning all, it's perhaps a little quieter this morning but that's understandable as it's not the best outlook really IMO, and the GEFS ensembles (not checked ECM but also similar I believe according to other posts) have trended milder overnight and don't really indicate anything particularly noteworthy (baring perhaps the S which at least flirts with some colder uppers a tad longer than elsewhere within the next week or so, but not much in the way of anything too

notable). 

GEFS for nr. Manchester

London

S cooler earlier on for longer.

But in the mid and longer term just a large amount of scatter and with nothing particularly of interest at this stage. Op slightly on milder side FI I suppose.

GFS op often HP influenced for us.

 

I'm not too disappointed with this morning's output because while there's been a good bit of optimism last few days from many which is always nice to see, I don't think we've ever really had an "active chase" in the last 4-5 days or so (after we realised this weekends Nly wasn't going to last) - it's not as though we've been chasing anything specific, the optimism has stemmed from decent looking NH profiles as well as other bits and bats which could indicate a trend to colder conditions. These may well still be in place - they just aren't quite translating into Op runs or ensembles/"eye candy" just yet. 

A few have indicated later December for a trend to cooler conditions - so I'm still optimistic for that. December week 4 on the balance of historic averages is always far more likely to have a colder spell than December weeks 1-2 of course. And Dec week 4 is still a million miles away in terms of the reliable timeframe of runs so all to play for. 

ECM deep into FI at least shows something which is perhaps a tad more promising. 

7 minutes ago, bluearmy said:

Gfs 00z op is (afaik) the first op this season to reverse the zonal flow in the strat.  Right at the top and down to around 3 hpa/80N

this is how full on reversals usually begin to show - its defintiely what we’d hope to see based on the direction of travel. Consistency please and down towards 60N! 

I've not a clue when it comes to the strat - but it's nice to know there's still optimism on that front as well!

 

48 minutes ago, mountain shadow said:

I actually think there is a chance we get lucky from a potent Northerly toppler.

If we keep on the trend of recent weeks/even months then I'd absolutely say another Nly blast could happen soon - I've been in that boat for a good few weeks now and to be fair I believe I was right - the other week after the November cold spell I said I wouldn't be surprised at some further Nly influences throughout December based on what we've seen since even as early as September (two Nly blasts in that month giving frosts). But Nly influences can be anything from a slightest graze of cold uppers from the N for less than 24 hours or something more potent, and are never a guarantee of snowfall, they come in all shapes and sizes. We have received two Nly influences in less than a week - Mon/Tues and the one upcoming Sun/Mon, both bringing cold uppers temporarily, but unfortunately not much in the way of snowfall away from Scotland (lucky Highlanders). But if we keep the pattern up and squeeze a few more Nly blasts in in the next few weeks, always a chance one could be potent enough for something more notable. 

[damianslaw]

Naturally people's attention is on the immediate outlook and potential impacts from Storm Darragh, which looks set to be nasty and coinciding with a very busy Saturday for many..

Looking far beyond the reliable the models are showing conflicting output, both ECM and GFS develop a shortwave feature in time for next weekend (weekends seem to be the time for worst weather at present), pushing high pressure aside and bringing in the atlantic again, but with a sign the jet will dig further south introducing colder PM air.. thereafter uncertainties all down to the interplay of the 2 PV lobes and whether we can punch any decdnt heights inbetween, or whether most energy is transferred into the siberian lobe allowing heights to punch and importantly hold in the Greenland locale. I'm expecting a lot of variable fayre from the models in the next 2-3 days as they grapple with these interplays.

We do have a seasonal settled rather cold spell to look forward to from Monday to Thursday at least - in the working week again!

[Dennis]

also in Ireland crazy winds 

[AO-]

28 minutes ago, StretfordEnd1996 said:

ECM deep into FI at least shows something which is perhaps a tad more promising.

Would not pay too much attention to EC this morning. It's like the 12h of two days ago. It is synoptically very different from its counterparts

[StretfordEnd1996]

 AO- Haha true, the chart I posted and was referencing was deep in FI anyway - was JFF really, I've got absolutely no belief in it, just at least shows one of the range of possibilities in the more immediate run up to Xmas with a flirt of Nly winds. (Though even at face value the chart itself I posted is not anything particularly eye-watering). 

[DaveF]

UKV predicts an extraordinarily sharp boundary between the calm in the centre of Darragh and the very strong winds on its western flank, especially as that boundary crosses the north of Ireland. It predicts a contrast between complete calm and 90mph winds over perhaps just a couple of miles. Does anyone have an understanding of the mechanism for this?

[Met4Cast]

Red warning issued 

[booferking]

We go red in parts of  Ireland to  

[Shaunado]

 TSNWK risk of nacreous clouds?

[Jacob]

 Shaunado What are those?

[AO-]

 StretfordEnd1996

Anything beyond 144 is deep FI at the moment. The shortwave is key between 144-168. Models are struggling a lot. But EC is an extreme example. Probably short lived ridge with hopefully locked in surface cold afterwards. Maybe the MJO will be in the game later in as well. 168 Is still within the range of the lag time of phase 4-5