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Nick F
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Posts posted by Nick F
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Met4Cast i am aware of how AAM and mountain torques are linked to the MJO. But I'm not convinced that the fluxes poleward or equatorward can specifically be linked to anomolous pressure tendencies in a particular locale, such as 'inflating Iberian / S Europe high pressure cells. What literature did you get that from? I would have thought Atlantic SSTs, TPV extending south from Greenland premoting WAA and expansion of Hadley cell north in winter would be the main drivers.
Does comes across to me like GDSM forecasting is an exclusive club who's members have secret access to AAM charts. Where do the rest of us find them?
The joy of this thread is everyone has access to a huge range of NWP charts now, much more than 2004 when I joined Netweather, so we can discuss, debate and challenge each other and those with less understanding can ask questions of the more knowledgeable. But with the GDSM posts by a few on here who have the special access generally go unchallenged and so readers just take your word for it.
I'm not saying I don't appreciate the time you guys put in to explaining how you interpret the AAM charts and come to your conclusions. But most of us don't know how these charts change with each update so can't discuss them and perhaps challenge why a previous forecast suggested x may happen but in the end the weather had other ideas.
When I started learning meteorology in depth in the early 00s no meteoroloy books or journals I remember refered to GDSM. But I have read some of the papers Blessed Weather has kindly put on Netweather. But still yet to be convinced it is any better than other tools for longer range forecasting.
Browsing wx forums in the USA, notably Americanwx, there is seldom reference of AAM by ProMets, only really on here gets a mention. Yet to be convinced myself, but you never know, I may be swayed more one day.
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5035396-
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Met4Cast i am aware of how AAM and mountain torques are linked to the MJO. But I'm not convinced that the fluxes poleward or equatorward can specifically be linked to anomolous pressure tendencies in a particular locale, such as 'inflating Iberian / S Europe high pressure cells. What literature did you get that from? I would have thought Atlantic SSTs, TPV extending south from Greenland premoting WAA and expansion of Hadley cell north in winter would be the main drivers.
Does comes across to me like GDSM forecasting is an exclusive club who's members have secret access to AAM charts. Where do the rest of us find them?
The joy of this thread is everyone has access to a huge range of NWP charts now, much more than 2004 when I joined Netweather, so we can discuss, debate and challenge each other and those with less understanding can ask questions of the more knowledgeable. But with the GDSM posts by a few on here who have the special access generally go unchallenged and so readers just take your word for it.
I'm not saying I don't appreciate the time you guys put in to explaining how you interpret the AAM charts and come to your conclusions. But most of us don't know how these charts change with each update so can't discuss them and perhaps challenge why a previous forecast suggested x may happen but in the end the weather had other ideas.
When I started learning meteorology in depth in the early 00s no meteoroloy books or journals I remember refered to GDSM. But I have read some of the papers Blessed Weather has kindly put on Netweather. But still yet to be convinced it is any better than other tools for longer range forecasting.
Browsing wx forums in the USA, notably Americanwx, there is seldom reference of AAM by ProMets, only really on here gets a mention. Yet to be convinced myself, but you never know, I may be swayed more one day.
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Derecho I've lost faith in using the MJO passage through the phases as precursor to changes in weather patterns towards cold or mild. Following 'warm phases' of 3-4 in early Jan we saw a 2-week cold spell, we've seen the MJO recently pass through 6 and now loitering and weakening through 7, but very little amplification in the upper flow at mid-to-high latitudes to show for it in the models. What high lat blocking that has been showing and will likely continue to be shown down to changes in the strat, i.e. downwelling of weakening winds.
And I don't get this obsession with using AAM as tool on its own, it seems that when ever it rises all falls we are told to look out for changes but it seems, like when the MJO moves through the historically 'colder' and 'milder' phases, many other drivers are at play, some not so obvious, drowning it out much influence from it over the N Atlantic sector / Europe. Though the biggest interference in what we would expect in lag to certain MJO phases being climate change.
The state of the stratosphere is one driver, when it couples with the troposphere, still one to keep an eye on though.
Be glad not hear about the MJO for several months, until the next cold season. I've given up talking about how it may influence patterns, as it makes me feel like a Snake Oil Salesman!
Original post: https://community.netweather.tv/topic/99814-model-output-discussion-22nd-jan-2024-onwards/?do=findComment&comment=5035341-
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Derecho I've lost faith in using the MJO passage through the phases as precursor to changes in weather patterns towards cold or mild. Following 'warm phases' of 3-4 in early Jan we saw a 2-week cold spell, we've seen the MJO recently pass through 6 and now loitering and weakening through 7, but very little amplification in the upper flow at mid-to-high latitudes to show for it in the models. What high lat blocking that has been showing and will likely continue to be shown down to changes in the strat, i.e. downwelling of weakening winds.
And I don't get this obsession with using AAM as tool on its own, it seems that when ever it rises all falls we are told to look out for changes but it seems, like when the MJO moves through the historically 'colder' and 'milder' phases, many other drivers are at play, some not so obvious, drowning it out much influence from it over the N Atlantic sector / Europe. Though the biggest interference in what we would expect in lag to certain MJO phases being climate change.
The state of the stratosphere is one driver, when it couples with the troposphere, still one to keep an eye on though.
Be glad not hear about the MJO for several months, until the next cold season. I've given up talking about how it may influence patterns, as it makes me feel fraudulent!
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Analysis of the risk of locally significant snowfall of higher ground of north Wales, N England and Scotland during Thursday and Friday. Also the risk of heavy rain and flooding in the south.
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damianslaw It's certainly been a painful and frustrating winter chasing cold and wintry weather, been plenty promise, some opportunity in Jan with the two week cold spell with easterlies and northerlies, but very little reward for many. A lot of bad luck too.
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Froze were the Days Think there is something in the idea that sub-tropical high pressure belts have shifted further north in winter recently, preventing cold getting as far south as it used to and explains drought persisting through the winter months now in southern Europe, as far north as the Alps.
The pub run trying to make up for its horror show with a BFTE tease at the end.
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Don The persistent high latitude blocking signal from EC46 over recent days still makes me optimistic of a cold end / last third to February. But my worry is the blocking could be too far north for southern UK to benefit, but northern areas could become cold at times. Every time cold patterns develops that seem to be too far north.
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Good grief, the pub run couldn't draw any worse charts for coldies this evening. Are we going to have to hope the likely SSW will reverse our bad luck this winter? Of course it may not be a quick trop response to it too. Or will the MJO / AAM help us out? A real struggle to keep up the enthusiasm for any cold and wintry weather coming down south before Feb's out at the moment!
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nick sussex Agree, quite a complex low pressure system moving in from the Atlantic later this week. 00z GFS perhaps looking the least likely to handle well the various low centres that develop and disappear within the low pressure system.
Differences between EC and GFS on baroclinic development around the southern side of the parent low moving in from the southwest across the Bay of Biscay. A strong jet streak moving E and NE underneath the parent low, EC shows wave developing over the Bay of Biscay which forms a low that moves NE across SE England early Friday. GFS doesn't have this low, but this low is quite pivotal in elongating the low pressure system and pulling the parent low east away with it and not allowing it to drift north over Ireland like GFS and Arpege do.
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TillyS You do like to bang the mild drum! Backing the mildest model run every time, regardless of where it sits in the ensembles. It won't always work.
The 00z EPS average supports high pressure to build after the coming weekend, not a return to Atlantic and mild southwesterlies that the op shows.
Looking dry and not particularly conducive for snow though. We may have to look beyond mid-month for better prospects, the extended ensembles have favoured the high migrating to Iceland and then Greenland with time.
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I guess if UKMO/UKV is the most southerly scenario and we discount the GFS then Midlands north look the best bet Thurs/Fri for snow on the northern edge of the rain moving in from the W/SW. Here's UKV:
A lot of uncertainty after this week, but it does look like low pressure will clear east on to the near continent to allow high pressure to build in the vicinity of the UK, a cold high. Would disregard the 00z GFS, which looks like it's on the mild end of the spread because it brings in the Atlantic.
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I would ignore the EC 0z as it is a clear outlier for 850s for Birmingham north around the time of the snow boundary. Birmingham:
The EC op doesn't look like an outlier to me on wetterzentrale spread for Birmingham, would treat those meteociel EPS spread graphs with caution, think they are too crude.
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EPS mslp mean has the late week / early Saturday low running through the Channel!
Trend GIF over last 4 runs shows the slowing of the low moving NE/E and also further south track. Ending up in France?
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A blog looking at how the current mild weather lasts into the first half of next week but then gets replaced by colder air later in the week, with an increasing risk of snow in places.
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Stunning sunset out my office window near Heathrow Airport earlier
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Today provisionally saw the warmest January temperature on record in the UK, with 19.6C in Kinlochewe in the NW Highlands. It's been rather mild this past week, but will we see colder weather return in February?
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Synoptic analysis looking at the arrival of Sahara dust and very mild air from the south over the weekend and into the start of next week. Maybe an idea not to wash your car for now! But could be some nice sunsets or sunrises.
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Grid values for UKV at 3am, can see why they issued a red wind warning
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A synoptic analysis looking at the development and impacts of Storm Isha arriving Sunday night and expected to bring widespread gales with potential for disruption.
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8 minutes ago, Mike Poole said:
T264+:
Cluster 1 holds the Scandi block in a good position, cluster 2 collapses back to +NAO, clusters 3 and 4 risk ending up with a UK high. This might retrogress on cluster 3 beyond the timeframe.
None of the extended clusters showing Atlantic troughing / upper flow energy undercutting high pressure building north over Europe that would hold a Scandi high in place for a sustained enough period to bring cold air our way though, so the high would eventually collapse. My worry is the lack of low heights especially over Iberia from Atlantic troughing undercutting, as well as further east over the Mediterranean Basin from undercutting of cold air from the NE, will mean we end up with a large Scandi-Euro High of little benefit to coldies in the UK other than some surface cold perhaps.
But, we know these clusters can change, so more runs needed. But I'd feel much happier if we saw troughing extending from the Atlantic over Iberia rather than the semi-permanent Azores ridging there. Extremely dry across parts of southern and eastern Spain this winter so far, due to lack troughing extending from the Atlantic over Iberia with ridging dominating.
We can get away with cold air undercutting high pressure over Scandinavia from the NE into southern Europe to lower heights over the central Med to bring a brief cold easterly, but prefer of the Atlantic troughing undercuts too to make it more sustained.
Original post: https://community.netweather.tv/topic/99793-model-output-discussion-cold-spell-ending-what-next/?do=findComment&comment=5018826-
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17 minutes ago, feb1991blizzard said:surely in your job you have to analyse the output!
I don't spend all day everyday doing it, weather forecasting is part-time work for Netweather, though also tweet a fair bit, wish I had more time to post on here but work life and home life gets in the way. I have a main job besides doing the Netweather articles. And it ain't weather forecasting I'm afraid.
Back to the models, as John H mentions, the UK isn't consistently bathed in Tm air for the next 10 days - alternating rPm and Tm air, but when we are in Tm, it could be very mild, like this Tuesday coming - with 14-15C on the cards, but Wednesday in rPm air and cooler
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Just now, AO- said:
Totally agree. But maybe first we should have some throughing over Poland/the baltics to suck the cold air South. We should not discount the history in this one. Here are two charts for dat 5 of EC g this morning. A southwesterly far into Russia. I dont think there will be much surface cold left in one week. That is what worries me the most atm.
True, the lack of cold from antecedent mild southwesterlies pumping deep into NE Europe and NW Russia is a worry, though with the right synoptic pattern developing, it can return there from the arctic fairly quickly before the rest of northern Europe can tap into it, but without the notably low temperatures we have seen build since November over Scandinavia, will any quickly developing cold pool be too marginal by the time it reaches here? All conjecture for now, as we have to get a Scandi high to develop and get and easterly flow far enough west in the first place.
Getting all the right pieces of the jigsaw to fall into place, not least getting cold air back to the NE and E Europe, a Scandi high to extend far enough west and crucially low heights over southern Europe to stop a high to the NE collapsing south, is an uphill battle to break out of the strong +NAO pattern ensuing.
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No signs of any deep cold from the 00z EPS yet ... long road back to cold and snow for now. Need patience of a saint in the UK if you've not seen lying snow yet this winter. Because it can get to you if you spend too much time over analysing and discussing the models each day, why I try to find other things to take my mind away from the disappointment of not seeing snow from this cold spell and seeing little on the horizon. Otherwise you just get frustrated.
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Winter 2023/24 - A Post Mortem
in Spring Weather Discussion
Posted · Edited by Paul
Tamara It's all very well and admirable learning about and explaining GDSM and how works in the bigger picture of the global atmosphere. Many of us, including me, appreciate this alternative and unconventional way of forecasting.
But it was the aggressiveness of the response from MattH when I dared questioned it's validity which was quite a shock to me and others.
Because the subject is very technical to understand and explain it immediately puts a barrier to most questioning its validity because they aren't confident to put up a counter argument with lack of data access.
If the GDSM is such a great tool, how come it's no longer available from NOAA. Or anywhere else. Met Office don't mention it publicly but do with all other drivers including MJO. There's no substantial evidence or papers that the theory is water tight and certainly with confidence can anyone attribute to AAM influencing weather patterns over N Atlantic.
We can't question those who make these predictions using GDSM because we don't have to hand archive charts, verification stats and any access to such data.
The thing that irks me is that predictions are made in MOD based on these GDSM / AAM plots but with little reference to other drivers, linked or not and we're told to ignore the model guidance. But, then there's never any follow up when these predictions don't come off as pescribed.