- Popular Post
Downburst
-
Posts
1,193 -
Joined
-
Days Won
1
Content Type
Forums
Blogs
Gallery
Events
Learn About Weather and Meteorology
Community guides
Posts posted by Downburst
-
-
I figured out why the Australian MJO forecast is higher in Phase 5 through 8 all the time. They are of course plotting these in the southern hemisphere and are upside down, so the line falls away from the COD naturally. Simple working this out in the end after trying to look into it this week.
-
1
-
2
-
-
3 hours ago, Spah1 said:
Can someone send me a link to learn about how to read these type of charts pls.
MJO
Tropics, starting in Indian Ocean and eastward movement of rain across the pacific (storms, with a lot of convection) occurs usually. This moved from the west to the east over time. It can be strong or weak and this can be measured. It can move fast or slower and again this can be measured.
What we measure?
The tops of the clouds at 200mb and the bottom layer at 850 pressure. This helps understand the strength of disruption. One can analyse previous pressure patterns (to pick one constant for this guide) and consider given the base state, for instance ENSO state what happened previously when the MJO was in this phase? One can then expect with certain probabilities that the atmosphere will react favourably to the way it has in the past. This is sometimes usefully shown in Composite pressure maps for the planet.
Recent forecasts have shown that as December progresses we can expect a possible Phase 7 to 8 transition at some amplitude (strength) and the composite pressure maps would suggest possible high level blocking in north Atlantic/arctic. Hence the interest. At the same time a low amplitude or not getting into these phases in time will not have any effect etc. There are so many variable.
As air rises a low pressure occurs and air enters underneath, a the top it cools and splits east and west. To the east it sinks and causes Higher pressure and less or no rain.
The whole process moves from the East all around the tropics over a month to 6 weeks and kicks off again.
Phases
Section the areas off and give them a number around the tropics. If in the area one gets that number.
These common Diagrams below, instead of MAP OF THE TROPICs, we can see the world split into 4 quarters, each quarter 2 phases of 8 total. It’s confusing at first, but it shows the current phase (Red), the previous phase and the forecast phase. But it also shows the amplitude of the phase, the higher above the centre circle the higher the phase, below the centre circle and it’s a very suppressed MJO signal. And of course, multiple ensemble runs to try to find consensus in the forecast. One can see even yesterday's plots show a lot of divergence in the 5 days forecast already, never mind Day 15 etc.
Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4972108 -
- Popular Post
- Popular Post
3 hours ago, Spah1 said:
Can someone send me a link to learn about how to read these type of charts pls.
MJO
Tropics, starting in Indian Ocean and eastward movement of rain across the pacific (storms, with a lot of convection) occurs usually. This moved from the west to the east over time. It can be strong or weak and this can be measured. It can move fast or slower and again this can be measured.
What we measure?
The tops of the clouds at 200mb and the bottom layer at 850 pressure. This helps understand the strength of disruption. One can analyse previous pressure patterns (to pick one constant for this guide) and consider given the base state, for instance ENSO state what happened previously when the MJO was in this phase? One can then expect with certain probabilities that the atmosphere will react favourably to the way it has in the past. This is sometimes usefully shown in Composite pressure maps for the planet.
Recent forecasts have shown that as December progresses we can expect a possible Phase 7 to 8 transition at some amplitude (strength) and the composite pressure maps would suggest possible high level blocking in north Atlantic/arctic. Hence the interest. At the same time a low amplitude or not getting into these phases in time will not have any effect etc. There are so many variable.
As air rises a low pressure occurs and air enters underneath, a the top it cools and splits east and west. To the east it sinks and causes Higher pressure and less or no rain.
The whole process moves from the East all around the tropics over a month to 6 weeks and kicks off again.
Phases
Section the areas off and give them a number around the tropics. If in the area one gets that number.
These common Diagrams below, instead of MAP OF THE TROPICs, we can see the world split into 4 quarters, each quarter 2 phases of 8 total. It’s confusing at first, but it shows the current phase (Red), the previous phase and the forecast phase. But it also shows the amplitude of the phase, the higher above the centre circle the higher the phase, below the centre circle and it’s a very suppressed MJO signal. And of course, multiple ensemble runs to try to find consensus in the forecast. One can see even yesterday's plots show a lot of divergence in the 5 days forecast already, never mind Day 15 etc.
-
2
-
1
-
13
-
2 hours ago, I remember Atlantic 252 said:
I remember day too well, the day LW252 went off air!
I used to see the mast, it was based in Ireland. Radio, someone still loves you! As Freddie sung to us. Good old Freddie.
It was the week before Christmas and nowhere in Europe or North Africa was above normal temps for the first time ever
-
3
-
1
-
-
- Popular Post
- Popular Post
Has to squeeze in here
-
10
-
3 minutes ago, sebastiaan1973 said:
This must be one of the highest UK barometer values. It would be a record for the time of the year in the Netherlands (around 1048 hPa)
1049.5 is December record for Ireland. Jan 19 2020 though must have been close, I took this photo on my barometer (old inches ) that went off the scale
-
8
-
1
-
-
13 minutes ago, That ECM said:
Although that’s about as over us as it can be.
Will take some shifting that PV to the north west.
-
It's all about the core of those Atlantic heights moving more northerly. We need the momentum to come from somewhere to do that. I have no idea if it will happen or not, but Scandi High seems out so we more or less know where to place the bets. Looking forward to next set of runs and the updated 46 day charts from ECM. But still plenty of time to build something good here.
-
2
-
-
Will have to keep a beady eye on the higher pressure anomaly (isn’t necessarily actually high pressure yet) south of Greenland moving north on future runs. Period 25th to 1st. But it’s brilliant to see even this genesis hint I have to say. Looks like Scandi high is out for now.
-
4
-
-
20 minutes ago, northwestsnow said:
EC 46 is superb
The only thing is the temps are normal to above normal. These being the temps corresponding to the upper pressure anomalies. So that has to be considered.
-
1
-
1
-
-
41 minutes ago, Met4Cast said:
What does this mean? I know what a warranty is obviously but not sure how that applies to weather models!
Sorry, a joke on the Korean "models" (car models) having 7 year warranties, which beat the likes of European cars (re ECM) with 3 to 5 year warranties and extrapolating to the NWP
-
3
-
-
10 minutes ago, Mike Poole said:
I think you might be trying to have your cake and eat it here? You’ve argued the ensembles are the right way to go week 2 and beyond, but with that comes the spread. The BOM chart shown by @Downburst says it’s an ensemble of 33 members and they are all amplified. So there is a difference - I’ll be much happier when the amplification into phase 7 is confirmed by other models, the BOM being the go to model all of a sudden has a whiff of cherry picking to me.
@Mike Poole @bluearmyHere is a paper, published 2022 from Copernicus, so more august body in my mind. Max-Planck Institute for the Physics of Complex Systems, Reading etc
From the Abstract: "Although in the last decades state-of-the-art climate models have proved their capability for forecasting the MJO exceeding the 5 weeks prediction skill, there is still room for improving the prediction. In 5 this study we use Multiple Linear Regression (MLR) and a Machine Learning (ML) algorithm as post-processing methods to improve the forecast of the model that currently holds the best MJO forecasting performance, the European Centre for Medium-Range Weather Forecast (ECMWF) model."
https://egusphere.copernicus.org/preprints/2022/egusphere-2022-2/egusphere-2022-2.pdf
I have given it a once over, but will have a more focused read later.
-
1
-
2
-
-
29 minutes ago, Crackerjack said:
I’ve just bought my brand new car from there ‘Hyundai’ so I’m all in as it’s a fabulous car
what does it mean Mike when it says it’s based on UKMO ‘unified’ model?
The South Korean weather model has a 7 day warranty apparently, has ECM worried with their 5 day warranty.
-
4
-
-
43 minutes ago, northwestsnow said:
Are we to believe BOM over GFS/EC though Blue ?
Big difference in the projected amplitude.
Interesting few days coming up..
As we all know the MJO is ticking away all the time since the ice age ended and there is a danger it will be taken too seriously for cause and affect when needed for a cause. I think the main issue I have is this BOM chart, seems always to be in insane amplification, like 100% more. So I'll be sticking with ECMWF and I certainly don't buy the argument that Australians have the MJO nailed in their computer models and the rest don't, hard to believe that given the age we are in and funding ECMWF and GFS get etc.
Dec 5th ECMWF
Dec 4 BOM
-
1
-
-
Would like a take on this, from ECM site and the long range.
2M Temp Area average Northern Europe, to show where this is, a map
A very large drop (Purple) in 2m temp compared to climate (Grey) for December showing there, purple box the middle tercile. This is opposite of the prediction last month which had December positive..
And NOA negative for each of the 3 months to come. Although it has been negative nearly all year. But near -3 for February, which fits into expctations.
-
2
-
2
-
-
The ECM MJO for Day 10, the mean line is now above the COD area for phase 6, whereas yesterday and a few days before it flirted with below. So phase 6 period is adjusting and it it continues we might see more towards the end of the GFS runs at least and perhaps shortly the 10 day ECM. Remember the higher the amplitude the more skill the forecast has historically, so maybe once the next 5 days finish we might get more consistency.
In saying all this, I am thinking, at least at the surface, that Canadian (+10c and corresponding Siberian -10 c temp anomaly this week is so strong, one has to wonder surely that will have more effect than anything else?
Also, over the last few days the 10hpa anomaly over the pole has really strengthened each run for 1st week of January. Although I won't hazard a guess (mini ice age end of January
) how and when that might effect us, especially so far out from even happening, but that's a strong signal all the same.
-
3
-
-
1 hour ago, sebastiaan1973 said:
A tweet by World Climate Service. We heading to a Modoki El Nino.
Yes, world climate service is not related to any UN or intergovernmental org etc. but I looked up some info on Modoki EL Nino, can’t find a reliable comment as to what this might mean to these parts, so I’ll leave this from WIKI and that’s saying a lot if you follow
Recent years when La Niña Modoki events occurred include 1973–1974, 1975–1976, 1983–1984, 1988–1989, 1998–1999, 2000–2001, 2008–2009, 2010–2011, and 2016–2017.
and again wiki
The first recorded El Niño that originated in the central Pacific and moved toward the east was in 1986.[77] Recent Central Pacific El Niños happened in 1986–87, 1991–92, 1994–95, 2002–03, 2004–05 and 2009–10.[78] Furthermore, there were "Modoki" events in 1957–59,[79] 1963–64, 1965–66, 1968–70, 1977–78 and 1979–80.[80][81] Some sources say that the El Niños of 2006-07 and 2014-16 were also Central Pacific El Niños
impacts on Europe, El Niño's effects on Europe are controversial, complex and difficult to analyse, as it is one of several factors that influence the weather over the continent and other factors can overwhelm the signal
Original post: https://community.netweather.tv/topic/99584-model-output-discussion-into-winter/?do=findComment&comment=4970099-
2
-
-
1 hour ago, sebastiaan1973 said:
A tweet by World Climate Service. We heading to a Modoki El Nino.
Yes, world climate service is not related to any UN or intergovernmental org etc. but I looked up some info on Modoki EL Nino, can’t find a reliable comment as to what this might mean to these parts, so I’ll leave this from WIKI and that’s saying a lot if you follow
Recent years when La Niña Modoki events occurred include 1973–1974, 1975–1976, 1983–1984, 1988–1989, 1998–1999, 2000–2001, 2008–2009, 2010–2011, and 2016–2017.
and again wiki
The first recorded El Niño that originated in the central Pacific and moved toward the east was in 1986.[77] Recent Central Pacific El Niños happened in 1986–87, 1991–92, 1994–95, 2002–03, 2004–05 and 2009–10.[78] Furthermore, there were "Modoki" events in 1957–59,[79] 1963–64, 1965–66, 1968–70, 1977–78 and 1979–80.[80][81] Some sources say that the El Niños of 2006-07 and 2014-16 were also Central Pacific El Niños
impacts on Europe, El Niño's effects on Europe are controversial, complex and difficult to analyse, as it is one of several factors that influence the weather over the continent and other factors can overwhelm the signal
-
1
-
1
-
2
-
-
I tell you what. Looking a the spread of those MJO plots really tells you how hard more than 10 days forecasting is, if not borderline impossible to be honest thinking about it. If you can't get that very complex forecast correct, the the knock on effects given this etc and try to predict weather in North West Europe for 20 odd days ahead? I think it's a lesson to everyone to be conscious of that, not only do we not know what phase we will be in, we don't know the amplitude, all we have is the mean really and a good look at the spread making that mean. I'd be even more careful of this Phase 7 to 8 for end of month, it doesn't have to happen.
-
5
-
1
-
-
There is a paper here on the Skill of the MJO models. The briefest summary is if the initial condition is in high amplitude the resultant forecast skill increases. Also some data outlining the number of days each major model attempts to predict for. And some mad maths in there too if you are brave enough.
To add, noaa produce verification for previous 7 and 15 days on their site
most recent ECM, hard to make a call there, seems to me the mean is looking not amplified and the initial conditions show a strong starting point, hence increasing skill of the forecast. But not my area at all
-
2
-
-
Mid December and looking at the ECM 500 hpa anomaly, seems to me there’s a chance of blocking to the north west or north east. Plenty of interesting options.
+NAO at 30% chance during this time, or glass half full way of expressing this is 70% chance of something else.
-
4
-
1
-
-
6 minutes ago, Premiere Neige said:
First thing that chart/gif said to me was "oh no you don't!". And it is pantomime season after all. Sorry....I'll get my coat
you won't need a coat, a jacket and umbrella will be fine
-
1
-
1
-
-
19 minutes ago, Snowy L said:
After seeing the huge BFTE being blown away with ease by a small low in 2018 I've never believed the cold is hard to shift myth, that was a rude awakening. With this cold spell though I do think there could be surprises, because we have positive reinforcements e.g. Canadian warming after the jet fires up, as opposed to waiting the inevitable after our initial block loses strength. If those reinforcements can affect the jet on time there's no reason we can't stay in the cold side. As said a few days ago the timing of those conflicting interactions will result in the messiest charts ever.
Yes and there is cold all over the northern hemisphere all winter, in many cases further south than here and yet the models aren't drastically wrong about that, so I can't see how the physics in the models doesn't account for it just because it's in north west europe, although I get the point, just not sure the models don't account for it. No hassle anyway.
-
1
-
1
-
-
You see it’s only a problem if you use the latest charts. Meanwhile yesterday using wetterzentral I was inadvertently looking at 24hr old ICON charts thinking my word that looks good compared to GFS. Gotten Himmel, for you ze 12z run is over.
-
1
-
Model Output Discussion - Into Winter
in Forecast Model Discussion
Posted
Right, we have set the bar, end December and January of 1963. Probably one or two bumps along the way, but I'm up in the attic later double lagging the pipes.
Extract from Met Eireann reviewing that period "The first major falls were during the last week of 1962, with particularly heavy falls on the 30th and 31st of December. Casement Aerodrome measured a snow depth of 45cm on the morning of the 31st. Another heavy snowfall occured on January 15th and snow lay on the ground in many places until a spell of milder weather in early February. Drifts of up to 6 metres caused severe disruption to traffic, while the Limerick Leader reported that for the first time in living memory the frozen River Shannon could be crossed on foot near the city. Further east in Europe, the weather was particularly severe. Ice formed on many North Sea and English Channel harbours, with sea ice also reported"