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Nick F

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    Storms and Convective discussion - November 2023 onwards

    in Storms & Severe Weather

    Posted

    SEVERE WEATHER WATCH - THURS 22 FEB 2024

    220224.thumb.JPG.43107619e4eb0e1372c05134b73eff82.JPG

    Issued: 21/02/2024 21z to 23/02/2022 00z

    • Strong wind gusts up to 45-60mph
    • Isolated tornadoes
    • lightning
    • Hail 
    • Intense rain leading to flash-flooding

    Areas at risk of the above: S IRELAND, SW ENGLAND, S WALES, S MIDS, S ENGLAND, E ANGLIA

    An upper shortwave trough emanating from NE Canada will sharpen as it tracks east towards the British Isles at the base of deep upper low centred near Iceland. The shortwave trough will engage a cold front ahead of it during Thursday, as it catches up with it, causing a wave to develop and eventually a surface low along it across southern Britain during the morning.

    Tonight, a cold front moving in across the far west this evening is already producing strong convection embedded within heavy rain along front, with quite active lightning activity noted across W Ireland and W Scotland. Broken band of heavy rain, with embedded convection will continue to move east across Ireland, N. Ireland, northern and western areas of mainland UK overnight, perhaps with isolated lightning toward western coastal areas.

    A separate cold front to the south will develop a wave from the SW during Thursday morning, in response to the upper shortwave arriving and engaging from the west. So heavy convective pulses of rain are forecast to develop across SW England, Wales and into Midlands, likely organising into a squall line due to strong low-level jet stream and shortwave trough axis arriving parallel to cold front. The squall line crossing east over Midlands, S England and E Anglia. Strong convective gusts of 45-60mph may be produced by the squall line, along with intense rainfall leading to flash-flooding and perhaps hail. Also, should broken line segments develop in the squall line, there is an enhanced potential for a brief tornado in the gaps where winds back ahead of the squall.

    Issued by: Nick Finnis

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    Winter 2023/24 - A Post Mortem

    in Spring Weather Discussion

    Posted · Edited by Paul

     Tamara i haven't debunked GDSM and I have no issue of you and others passion and in depth explanantions of how it may affect weather patterns, but I do think it's used too much in isolation to make predictions at the expense of the caveats that other drivers are also driving the patterns.

    I'm sure the reactions from some of the more defensive replies I've seen on this forum would be different if we met face to face rather than online in front of a screen. Spent many a joyous time with Chinomaniac and Lorenzo sharing stuff on storm forecasting and listening to them with their knowledge of the strat face to face on storm chases and other meet ups, plenty of constructive debate. Also Thundery Wintry Showers, Blessed Weather plus others I've met in real life and had some great conversations. 

    The web makes too many invincible, confrontational, rude, aloof, defensive and generally behave differently when challenged than if they talked face to face.

     

     

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    Winter 2023/24 - A Post Mortem

    in Spring Weather Discussion

    Posted

     Tamara That doesn't doesn't give the excuse to be condescending for those that question the GDSM tool. How can it be verified that AAM is implied in more likely being responsible in creating certain patterns and not other drivers? Which begs the question how can you and others be so confident? 

    Again, it feels like closed doors to those to question the tool's validity for fear of being shot down because they don't have the hours of learning the subject and all the GDSM updates to hand to draw on to be able to question a prediction. 

    I don't doubt that GDSM has It's place, but many of your posts seem mostly centred on the evolution of AAM to make predictions and not talking about other drivers and persuading the reader to disregard model guidance. Then when patterns do not evolve how you suggest, there is no admittance by you why it didn't play out how you predicted.

     

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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. 

     

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    Model discussion highlights

    in Forecast Model Discussion

    Posted

     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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    Winter 2023/24 - A Post Mortem

    in Spring Weather Discussion

    Posted · Edited by Nick F

     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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