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Convective/Thunderstorm Discussion : 2019 and Winter 2020

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  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


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    Day 2 Convective Outlook
    VALID 06:00 UTC Sat 06 Apr 2019 - 05:59 UTC Sun 07 Apr 2019

    ISSUED 19:25 UTC Fri 05 Apr 2019

    ISSUED BY: Dan

    ... ISLES OF SCILLY / CELTIC SEA ...
    On the northern edge of the elongated upper low to the southwest of the British Isles, a shortwave will move northwestwards across the Celtic Sea and southern Ireland on Saturday. Elevated showers and one or two thunderstorms will be possible over the Scilly Isles initially, and over open waters to the south of Ireland during Saturday morning.

    ... IRELAND ...
    The associated cool mid/upper-levels with the aforementioned shortwave atop surface heating over southern and western Ireland will help generate a few hundred J/kg CAPE. However, main limiting factor is the fact that the shortwave is likely to move through before peak heating, so questionable as to how much of a favourable overlap will exist. Nonetheless, a few isolated showers seem possible for a time within a reasonably sheared environment, and hence at least a low risk of lightning.

    ... E ENGLAND ...
    Towards the end of Saturday night (i.e. nearer 06z Sunday) remnant / weakening instability will drift across the North Sea towards eastern England, with the potential for a few elevated showers atop a very moist boundary layer (sea fog / low cloud quite likely). There is a very low risk of a few isolated lightning strikes with these showers, however given weak instability and very late arrival (it could be beyond 06z before any make landfall) for now we refrain from issuing any threat levels here.


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Bit of interest for the SW tomorrow to see if we get some lightning, like was said above the trough might be gone through before heating gets going, but a few clouds could get mature enough to become electrified in the afternoon perhaps. More DLS available then previous days, 2m temperature warmer at about 13C but 850 hPa temp up to about 0C or so and 500 hPa about -25 to -29C . The DLS might just swing it. If there is lightning I would take a punt and say possibly W, Cork, Kerry , Limerick or Clare ( will leave it a wide enough area :) ).

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  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


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  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Bursts of sunshine getting through here near Tralee. I'm interested to see if conditions will produce lightning here in Kerry this afternoon. Cape looks good, LLS good, steep lapse rates, DLS not showing as good but some available nonetheless. K- Index higher than it has been recently. With these weather conditions passing over Kerry mountain lift might aid the development of a thunderstorm. Will see.

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  • Registered Users Posts: 4,668 ✭✭✭SleetAndSnow


    A few strikes starting to show up on the south coast now on Met Eireann site and blitzortung


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  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Just a few strikes well off the coast in the end. Nice big cloud structures here in Kerry with good sunshine, some showers showing up especially in mountainous areas but in general I would think nothing too heavy.

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  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    As Kermit said over in the Spring thread, Thunderstorm potential on Tues as a a trough passes up over the country. Temperatures look good getting up around 19- 20 C so good diurnal heating. Low and mid level shear looks favourable. Bit of interest .


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  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    There could be other opportunities for thunderstorms as the weather gets more unsettled during the week with upper lows and troughs and we could be seeing very cold uppers again by the weekend. A lot going on as the week progresses.


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Wondering if there is small chance that a few sporadic showers might be locally heavy and become electrified as they cross the country later tomorrow from the SE towards a NW direction . A few cells might fire up over in Wales and make there way across to the SE /E ? Lower and mid level shear look decent, high Theta E readings later.

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  • Registered Users Posts: 7,095 ✭✭✭pad199207


    Perhaps the Wicklow mountains might aid with some lift. It’s happened before many a time in that sort of setup.


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  • Registered Users Posts: 2,023 ✭✭✭Donegal Storm


    Looking at the charts this morning and I immediately thought thunderstorms for the week ahead, cold air in a southerly flow this time of the year can give us some good intense thundery hail showers. Here's hoping!


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Interesting in depth piece from Convective Weather. Had noticed a big difference for tomorrow between the GFS / WRF - NMM and ECM all right . Good to hear their take on the models being mentioned .


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    Day 2 Convective Outlook
    VALID 06:00 UTC Mon 22 Apr 2019 - 05:59 UTC Tue 23 Apr 2019

    ISSUED 21:08 UTC Sun 21 Apr 2019

    ISSUED BY: Dan

    Atlantic longwave trough will continue to dig southwards during Monday towards western Iberia. As a result, southerly flow aloft across the British Isles will gradually back southeasterly, advecting relatively high ThetaW airmass from France into southern and central Britain. Areas of medium/high level cloud will occasionally drift northward courtesy of weak mid-level instability and increased moisture aloft.


    Deep mixing will likely occur through the day, resulting in steep low-level lapse rates. However, this will also likely mix drier air down to the surface, resulting in low dewpoints and large dewpoint depressions. Subtle forcing aloft will drift over S / SW Britain on Monday afternoon, coinciding with peak surface heating. This combined with low-level wind convergence and orographic forcing may allow a few isolated heavy showers / thunderstorms to develop late afternoon or evening, primarily Somerset/Glocs and into Wales. There could also be one or two over Ireland.

    However, the vast majority of NWP guidance remains sufficiently capped to prevent any thunderstorm development. GFS and derivatives (WRF, NMM) often produce profiles that are excessively moist, and hence suggest much higher surface dewpoints than most other models for Monday afternoon. Consequently they often favour thunderstorm development - especially over mountainous areas - when in similar events in the past such storms have failed to materialise. UKV and AROME have also been known to be too keen for thunderstorm development in fairly capped environments.
    As such, it is plausible that no thunderstorms may develop at all. That said, a broad LOW threat level has been introduced to cover the risk - at this stage it is difficult to be more precise where an isolated shower/storm may develop, though S + W Wales is most favoured. If confidence does improve a small SLGT may be introduced. Should a storm develop, given forecasting soundings and the potential magnitude of CAPE, there could be quite a bit of lightning locally. Any activity would then drift NW-wards towards eastern Ireland during the evening hours.

    On Monday night, pulses of showery rain will move into S / SW England containing the remnants of deep convection originating from northern France. Weak instability suggests any lightning activity with this should be fairly isolated.


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Only one sferic detected off Devon I think late afternoon / early evening . Showers about but nothing out of the ordinary, some more organised rain heading towards the S of Ireland , but no big cloud formation showing up on Satellite.

    ECM showing the SW with a bit of convective potential tomorrow in the first half of the day tomorrow.

    WRF -NMM showing the most potential but as Convective Weather were saying not always accurate overestimating the signals. ECM not showing much rainfall in the afternoon until later in the evening when best chance again perhaps is a few cells migrating across the Irish sea. Not much happening but good to observe the marginal set ups.


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


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    Day 1 Convective Outlook
    VALID 06:00 UTC Tue 23 Apr 2019 - 05:59 UTC Wed 24 Apr 2019

    ISSUED 06:01 UTC Tue 23 Apr 2019

    ISSUED BY: Dan

    ... TUESDAY AFTERNOON / EVENING ...
    Negatively-tilted longwave trough will continue to be located to the southwest of the British Isles on Tuesday, creating a southeasterly flow aloft with subtle disturbances running northwestwards along the forward side of this trough. As a result the overall pattern is very similar to Monday, with pulses of medium/high-level cloud associated with weak elevated instability, but a generally capped environment to surface-based convection.
    However, provided sufficient moisture pooling can occur along a zone of low-level convergence from Glocs/NE Somerset northwestwards across S + W Wales, then a few isolated heavy showers / thunderstorms will be possible during the late afternoon and evening hours. This is rather dependent on surface dewpoints reaching 12-15C, and it must be noted that on Monday afternoon dewpoints generally remained below 10C when GFS simulated 12-14C, hence proving the point that GFS (and associated WRF/NMM) produce excessive moisture and are therefore too "trigger-happy" with developing deep convection.

    Nonetheless, deep convection does seem more likely than was the case on Monday - and a low-end SLGT has been introduced to better highlight the area of interest, though it is certainly possible no thunderstorms may occur. There is better model agreement on the potential for a few isolated showers / thunderstorms during the late afternoon / evening across NW Ireland, more especially as they move offshore, hence the inclusion of a low-end SLGT here - this dependent somewhat on sufficient cloud clearance during the afternoon hours.

    ... TUESDAY EVENING / NIGHT ...
    During Tuesday evening / night, increased forcing aloft as the upper trough approaches from Biscay will encourage elevated convection to develop over NW France / English Channel and drift towards SW England. However, this will tend to turn increasingly dynamic with time as instability weakens. Nonetheless, pulses of showery rain will push into southern Britain and southern Ireland during the overnight hours, capable of producing a few lightning strikes from elevated instability. However, this is unlikely to be active or widespread enough to warrant a SLGT by the time such convection reaches land.


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    Interesting seeing the point Convective Weather raises with the WRF-NM showing much higher Dew Points than the ECM.

    ECM showing a couple of hundred j/kg CAPE in the W later this evening. Convergence along the coast there giving lot's of low level shear .Will see if anything materializes.



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  • Registered Users Posts: 1,979 ✭✭✭squarecircles


    in the zone here in west Mayo where convective/thunderstorms are possible today,the sky this morning looks ominous,sick,brooding,navy/orange skies,slack winds with the classic continental haze fading out the mountains,the grass velvet lush green,the buds blooming.


  • Posts: 21,179 ✭✭✭✭ Stevie Muscular Top


    in the zone here in west Mayo where convective/thunderstorms are possible today,the sky this morning looks ominous,sick,brooding,navy/orange skies,slack winds with the classic continental haze fading out the mountains,the grass velvet lush green,the buds blooming.

    And then you woke up ! haha ;)


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


    What a bust today, just one sferic detected in Kerry this afternoon from what I can see.

    Tomorrow showers followed by a front crossing the country later in the early evening. ECM showing 600 + j/kg of CAPE late afternoon early evening in the W. The W looks to have the warmest temps tomorrow.

    Met Eireann mentions risk of Thunder more associated with the frontal rain I think. Convective weather very quiet about Ireland tomorrow but giving it a low risk. Should see a lot of Lightning and heavy rain around the midlands in the UK tomorrow.

    IMO Thursday looks like the most active day with a negative tilted trough and a very cold pool aloft.

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  • Registered Users Posts: 13,477 ✭✭✭✭sryanbruen


    Didn’t hear any thunder but it was a nice evening for cloudscapes here in Dublin after a mostly dreary afternoon with light rain.


  • Moderators, Science, Health & Environment Moderators Posts: 11,763 Mod ✭✭✭✭Meteorite58


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    Day 1 Convective Outlook
    VALID 06:00 UTC Thu 25 Apr 2019 - 05:59 UTC Fri 26 Apr 2019

    ISSUED 20:42 UTC Wed 24 Apr 2019

    ISSUED BY: Dan

    Upper trough, with main axis over Ireland, will slowly creep eastwards across the British Isles during Thursday. This will be accompanied by a marked cold pool aloft, steepening mid-level lapse rates.

    Due to the complex upper pattern, there is still at this stage marked variations in NWP guidance as to the exact track / shape / timing of a surface low and associated area of precipitation (occlusion) which will likely move northwards across England and Wales on Thursday morning. Strong upper forcing and marginal instability may result in a few isolated lightning strikes with this feature, though in general the risk is considered rather low.

    The main focus for lightning activity will be within the post-frontal environment, as increasing insolation results in surface heating beneath increasingly dry air aloft. This will increase instability, generating 300-500 J/kg CAPE which combined with areas of frictional convergence will aid in the development of scattered showers and a few thunderstorms.

    Greatest risk of lightning is likely to be in a zone from SE Wales / SW Midlands northeastwards to NE / E England during the afternoon and early evening - a low-end SLGT has been issued here. A second area of interest could be inland parts of Ireland, though here a lack of shear suggests convection will be both slow moving and rather "pulse-type", with a risk of some localised water issues due to slow storm motion. Cloud cover is also some concern here given close proximity to some frontal rain at times - a low-end SLGT has been issued here.
    In general, the best shear will exist across East Anglia / SE England, though here the potential for deep convection is somewhat restricted due to a shorter land track to the surface wind, and perhaps also slow cloud clearance depending on the timing of the earlier frontal rain. Nonetheless, decaying showers/storms from northern France may push into SE England later in the day, but probably with a weakening trend.

    In any case, lightning activity is not expected to be as prolific as was the case on Wednesday, and any individual storm may only produce a few sporadic lightning strikes. Many places within the SLGT areas will likely remain void of any lightning. Quite a few reports of generally small hail are likely, perhaps locally up to 1.5cm in diameter. A couple of funnel clouds / weak tornadoes will be possible, primarily in Ireland with the best low-level convergence. Showers/storms will tend to decrease in intensity and coverage as daytime heating subsides.


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  • Registered Users Posts: 18,069 ✭✭✭✭fryup


    well going by ventusky we're in for some light show this evening


  • Registered Users Posts: 10,024 ✭✭✭✭Oscar Bravo


    Lightning west of Clonakilty


  • Registered Users Posts: 10,024 ✭✭✭✭Oscar Bravo


    Some very intense cells near Fermoy


  • Registered Users Posts: 6,466 ✭✭✭jimmynokia


    UK getting a nice show.. Again..


  • Registered Users Posts: 3,116 ✭✭✭dashoonage


    Two rumbles and some flashes in Limerick a few minutes ago... power flickered as well


  • Registered Users Posts: 7,095 ✭✭✭pad199207


    Very heavy rain in Kildare for the past while


  • Registered Users Posts: 6,466 ✭✭✭jimmynokia


    Over house a few mins ago[URL="[img]https://i.imgur.com/uLlu1Vh.jpg[/img]"]uLlu1Vh.jpg[/URL]


  • Registered Users Posts: 3,031 ✭✭✭redsteveireland


    Had some nice thundery showers travelling up the M6 earlier with some heavy hail around Ballinasloe.


  • Registered Users Posts: 7,095 ✭✭✭pad199207


    Thunder here in Kildare. Heavens look like they are about to open.


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  • Registered Users Posts: 269 ✭✭Mount Vesuvius


    And the heavens have indeed opened up Pad.
    Gutters can't handle it. Patio like a river now. This will soften the ground abit before Hannah's arrival, trees in full leaf too. Winds won't be as strong this side of the country but might be enough to cause damage.


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