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Atmogenic

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    Storms and Convective discussion - June 2023

    in Storms & Severe Weather

    Posted

    1 hour ago, Eagle Eye said:

    Good morning, me and Jay's first ever high risk, its a historic day ha ha.

    Sunday 10:00 - Monday 08:00

    Widespread MUCAPE 1000+ J/KG with locally 2500+J/KG of MUCAPE means that fairly significant thunderstorms eith frequent lightning are likely fairly widespread when the capping is broken. Similar to yesterday, the capping means that vigorous convection can take place and there's likely to be enough forcing and energy overlapping to create clusters of storms in areas.

     

    Multiple shortwaves and a forming surface low provide the lift for very strong Theta-E and energy as it is pulled up from our south. Very warm temperatures mean that the capping in place is likely to be broken from surface heating early to mid afternoon and provide ample bouyancy for active thunderstorms fairly widespread, especially in the Oxfordshire across to the Llanidloes region where we have issued a tentative high risk as only one model doesn't show widespread thunderstorms in that area. That is the UKV but it's already behind the showers in the channel whereas the two models handling those showers very well, the AROME and the WRF show strong thunderstorms in that corridor.

     

    Given the amount of energy, strong thunderstorms are possible pretty much anywhere but with varying levels of confidence. The moderate and high risk are most likely to see these active storms with most models showing ample energy there to provide vigorous convection.

     

    Given such high moisture and PWAT values and the surface-latching nature of these storms (quite low LCL's), two severe's have been added for possible surface flooding from these possible storms. 1 to 1.5 inches of rain could fall within an hour in some areas which could lead to surface flooding in the strongest storms.

     

    The close to surface LCL's and EL's ≈ 12km lead to significant entrainment CAPE. The low amount of shearing may mean that if these storms cannot last long enough, they won't reach that height but given the significant bouyancy and CAPE, the convection is likely to be vigorous enough to quickly use up that energy. If forcing and bouyancy work together they can counteract thst shearing further by lifting the storms above 12KM, so we may see even taller storms somewhere. Generally the more entrainment CAPE and the taller the storm, the more frequent the lightning. So with these tall storms with significant entrainment CAPE, frequent lightning is probable somewhere.

     

    Along with 200+ J/KG of 3CAPE (0-3 KM averaged out CAPE) meaning that significant thunderstorms are looking likely especially in the moderate and high risk areas. Just for reference 50+ J/KG is typically for strong thunderstorms (surface based ones) and we had around 150+ J/KG yesterday in spots. 

     

    So, more active and stronger thunderstorms than yesterday are possible. It's possible that they could form low-end severe hail though the steep 0°C line means the hail growth zone is quite small compared to usual. Between roughly 7km up to cloud height means that storms have to reach their maximum theoretical height and take in a lot more of their 0> CAPE to grow that type of low-end severe hail. Along with that hail growth detriment, the shear is generally non-supportive and a weak or near non-existant inflow strength doesn't support severe hail. Generally you want the inflow and the shearing to form a C shape with weak low-level shear and strong deep-layer shear. There's moderate low-level shear and weak deep-layer shear. So despite the strong 3CAPE which can sometimes support severe hail almost by itself, severe hail is unlikely and the severe is just for surface flooding.

     

    These storms are likely to be slightly more saturated than yesterday, weakening the lightning potential but given the pure amount of energy in the atmosphere, that shouldn't do too much. It may make the day slightly weaker than forecasted by models such as the AROME but only very slightly.

     

    The surface lift is strong and similar to yesterday so late initiation won't mean too much to eventual strength just like it did yesterday. All late initiation would do is strengthen the vigorousness of convection that gets going and weaken how widespread the convection gets.

     

    Some models then show as the showers in the channel around the central south hit the south coast they should start building up especially as they get further inland and move towards Gloucestershire and Wales hence two rounds of thunderstorms are possible for the southern area of the high. Some models show that as the main convection in that area with it forming a strong storm but other models dont show it forming into much. We've seen it in similar events before where there is significant surface energy after dark which forms thunderstorms from weakening channel showers. Currently this looks to take place west of Southampton, maybe in Southampton if there's a slight eastern shift and across to Dorechester moving NE towards Cardiff overnight, definitely something to keep an eye on radar on if you're between those areas and want a good late evening/early night time (11pm) roughly, storm but its not a guarantee.

     

    So significant thunderstorms with frequent lightning are possible. Strong surface flooding and near-severe hail may be possible as well. Generally, a high end event appears plausible today especially in Gloucestershire and the Wales-England border general area.

    20230611_093242.thumb.jpg.1b312f10af5783dd4dd5afe19a6a7819.jpg

    I'm not weather expert here, but I don't agree with the far southeast being in the green, I believe it should be in the white as it will be a very low chance we will get anything here

    Drought Watch

    in Spring Weather Discussion

    Posted

    it hasn't rained since I came back from florida on May 14th and funny enough when we went to florida for 2 weeks (april 30th - may 14th) it also didn't rain at all. It's like i'm a curse and brought all this dry air with me from Florida 😂

    SE, London & EA - Weather Discussion

    in SE, London and East Anglia Weather Discussion

    Posted

    5 minutes ago, TN9 said:

    Well nothing here in Maidstone now all melted away like my ice cream ..cor it was hot.. hotter than what I thought it would be..or I'm just not used to it .. not having a lovely north easterly breeze  five weeks of it ..but with sun out its a  beautiful wind ..

    I agree with that, it was a shock to my system not having that horrible wind there, but I've loved every bit of it as long as you're prepared going outside

    • Like 1

    Storms and Convective discussion - June 2023

    in Storms & Severe Weather

    Posted

    4 minutes ago, Flash bang flash bang etc said:

    Sounds like rain wrapped and / or elevated lightning is making it difficult to see the bolts

    I meant in general not particularly lightning shots, either the storms are mixed in with other clouds to not get a good view of them or some people are recording the ones that are currently under them

    • Like 2

    Emergency Alerts - GOV.UK service

    in Storms & Severe Weather

    Posted

    6 minutes ago, Bristle Si said:

    Yep, went off at 3.

    Still, for the life of me, cant get why so many were making a fuss about it. Too much time on other social media i suspect, together with a general opposition to anything coming from HMG.

    Get over it.

    exactly what i was thinking, it only goes on for about 5 seconds and they act as if it ruined their entire day 😂

    • Like 4
    • Thanks 1
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