Jamie M

Thunder right at the end

Benson METAR has a drop of at least 8C and winds gusting up to 60 km/h (37 mph)

Really has gone ham

Coventry

Basingstoke

Lovely stuff

CG

Heathrow

Certainly looks it

Thunderstorm imminent

Hallelujah

Can only imagine the show of lightning I'd be getting after sunset

14 mm and a drop of 7.7C at Charlwood within the last hour

The difference between capped and uncapped is evident

To my SW at the minute, can see it trying further west but failing

Day 2 Convective Outlook VALID 06:00 UTC Sun 11 Jun 2023 - 05:59 UTC Mon 12 Jun 2023 ISSUED 21:56 UTC Sat 10 Jun 2023 ISSUED BY: Dan On Sunday, an upper ridge will stretch from the North Sea and down across western Europe, while a cut-off upper low loiters over the Atlantic to the west of Biscay. Between these two features, a relatively high Theta-E airmass will cover much of the British Isles providing the potential for another day of deep convection and thunderstorms. The exact forecast evolution is very uncertain, with a considerable amount of inter and intra-model variability. As such, broad themes will be discussed but unlike Saturday when there was a clear foci for thunderstorms this will be more challenging for Sunday. At the start of the forecast period, showery outbreaks of rain and embedded elevated convection may be ongoing across parts of Scotland (western areas especially), and perhaps also across parts of the English Channel / southern England, both associated with areas of PVA embedded within the rather weak south/southeasterly flow aloft. In these areas rain should gradually dissipate and/or clear through the morning, and while cloud cover across the British Isles is uncertain a degree of surface heating is anticipated given largely medium/high level cloud present (away from Ireland, western Scotland and SW Britain where fairly extensive low cloud/coastal fog is possible). The presence of a stout EML over central/eastern Britain will require near-surface temperatures to exceed 27-28C to eradicate surface-based CIN, while farther west towards Wales/West Country less capping is likely with lower initiation temperatures (23-24C, for example). The main caveat here is cloud cover and whether surface temperatures can reach/exceed these values, whereas in eastern Britain greater insolation should allow near-surface temperatures to reach/exceed required values. However, even if SBCIN can be eroded in eastern Britain, the strengthening upper high in the vicinity and associated very dry, subsided mid-level profile will probably work against any deep convection. Towards the Midlands, Wales, SW England, forecast profiles are moister with less evidence of subsidence and therefore more conducive to deep convection. Given the rather slack flow, convective initiation will probably rely heavily on both surface boundaries/upslope flow and any subtle features aloft - and this is where large discrepancies are evident in various NWP guidance. A small surface low over SE England on Sunday morning is expected to migrate/expand slowly northwestwards into the Midlands, and this will influence the low-level wind flow while also maximising low-level convergence in its vicinity. Therefore the exact shape/track of this low will be instrumental to areas most likely to see shower/thunderstorm activity. In a broad sense, scattered heavy showers and thunderstorms may develop over portions of Wales (aided by upslope flow/sea breeze) and across the Midlands/Cen S England during the afternoon hours, persisting into the evening. Modified forecast soundings yield MLCAPE of 1,000-1,500 J/kg CAPE, locally higher, with cloud tops potentially to 40,000ft. However, given weak flow aloft (<10kts at 500hPa) effective shear will be rather weak, leading to rather pulsey/outflow-dominant slow-moving storms with cold pools aiding the development of daughter cells nearby. Nonetheless, the magnitude to CAPE will be sufficient for some fairly active thunderstorms, capable of producing marginally-severe hail in the strongest cells. Of greater concern, however, is the potential for surface water flooding, especially across the west Midlands, east Wales and West Country where PWAT of 30-40mm, moister profiles (less evaporation) and a tendency for storms to become prolonged/morph into clusters. The well-mixed boundary layer will also be supportive of wind gusts 40-60mph locally near the most intense cells. This whole scenario is also complicated by potential for PVA to arrive from France, partly enhanced by previous day convection, which could result in a much larger area of heavy convective rainfall across parts of S/SW England - this aspect is uncertain. Elsewhere, scattered heavy showers and thunderstorms are likely to develop over hills in northern England and portions of Scotland on Sunday afternoon and evening, drifting slowly to the north or northeast. Some of these storms could be fairly active lightning-wise, with scope for some marginally-severe hail over northern England in particular. In Ireland/Northern Ireland, despite increasing instability in response to surface heating, a warm nose in the 600-700hPa layer may inhibit much in the way of deep convection, hence have refrained from including any higher threat levels at this stage. Depending on how things evolve on Sunday afternoon/evening, some clusters of showers/thunderstorms over Wales/NW England may migrate northwestwards across the Irish Sea on Sunday night towards the Isle of Man/SW Scotland/east coast of Ireland. In addition, there have been hints of mid-level showers drifting into SE England (and perhaps East Anglia) on Sunday night within the residual instability plume - although whether much lightning occurs with this activity is uncertain. Finally, there is scope for an uptick in showers/thunderstorms over eastern Scotland during the early hours of Monday, although limited cross-model agreement casts a lot of uncertainty over this potential.

Day 1 Convective Outlook from Dan Holley on Convective Weather VALID 06:00 UTC Sat 10 Jun 2023 - 05:59 UTC Sun 11 Jun 2023 ISSUED 07:36 UTC Sat 10 Jun 2023 ISSUED BY: Dan Between an upper ridge over western Europe/North Sea (surface high over Scandinavia), and a longwave upper trough to the west of Biscay, a broad southeasterly flow will continue to advect relatively high Theta-E northwestwards across the British Isles from France. Showery rain/elevated convection will likely be ongoing at 06z Saturday across the Channel Islands, western English Channel, SW England, SW Wales and parts of Ireland in the vicinity of a NW-SE orientated occlusion. The extent of cloud cover associated with this activity as it drifts slowly northeastwards (individual clusters moving northwestwards) may, to an extent, impact the potential for deep convection later in the day, especially over Ireland. Ahead of this zone of cloud and showery rain, strong heating across the Midlands, Wales and southern England with Tmax of 24-27C anticipated widely and locally 30-31C in/around London will lead to a deep and well-mixed boundary layer. Analysis of forecast soundings suggest near-surface temperatures of 26-27C or higher will generally be required to overcome low-level capping, while very dry air persists in the mid-levels due to subsidence associated with the nearby upper ridge. This casts some uncertainty over how much deep convection will be able to develop, and it is plausible convective cloud may undergo several attempts at gaining height before become sustained, delaying true initiation until later in the afternoon. Nonetheless, profiles are anticipated to moisten fairly rapidly in the mid-levels across Wales and the West Midlands towards and beyond mid-afternoon as a shortwave approaches from the south (so here earlier initiation perhaps most favoured), while at the same time a surface low is signalled to develop over the SW Midlands. A brisk southeasterly wind across central and eastern England will aid moisture pooling along a strengthening NW-SE low-level convergence zone roughly in the vicinity of the M40-M6 corridor, with near-surface dewpoints of 15-18C signalled. This, in conjunction with orographic forcing in Wales and the West Midlands, will likely provide the focus for scattered, relatively high-based thunderstorms to develop in a fairly explosive manner, especially late afternoon and into the evening hours, growing upscale into a larger cluster across N Wales and parts of NW England. Forecast soundings suggest the potential for MLCAPE on the order of 1,000-1,500 J/kg generally, but perhaps locally 2,000 J/kg where higher dewpoints exist, with cloud tops potentially to 40,000ft (-60C or colder). While flow aloft will be fairly weak (~15kts at 500hPa, for example) a reasonable degree of low-level wind shear is evident with slightly backed near-surface winds. Despite limited shear, the magnitude of instability may be sufficient for the strongest cells to become better organised with potential for some transient supercell characteristics. All-in-all, the environment will likely be conducive for some very active, slow-moving thunderstorms that may train over similar areas given steering flow roughly parallel to CZ, greatly increasing the risk of significant surface water flooding (30-40mm in less than 1 hour), especially over urban areas. Hail will likely be sub-severe for the most part, but any stronger/sustained cells could potentially produce hail ≥2cm in diameter. A SVR has been introduced for the risk of flash flooding, and to a lesser extent for locally severe hail. The deep, well-mixed boundary layer/inverted-V profiles suggest the potential for rather gusty winds, 40-50mph in the strongest cells. Greater coverage of thunderstorms is anticipated across the W/NW Midlands, C/N Wales and into NW England, where associated MDT and HIGH risk areas have been introduced, while activity will be more isolated/conditional further southeast towards London. That said, similar setups in the past have sometimes produced a rogue thunderstorm to the NW of London in the mid-late evening. While nocturnal cooling at the surface occurs through the evening/night, substantial CAPE will persist given the existing deep mixed layer in the low/mid-levels, and with strengthening 600-850hPa flow through the evening this will advect more rapidly northwestwards across the Irish Sea, and eventually towards SW Scotland/Northern Ireland, and later W/NW Scotland. As such, there may be an uptick in elevated thunderstorm activity over these areas during Saturday night as the shortwave over Wales at 18z continues to migrate northwestwards. Elsewhere, a couple of surface-based showers/thunderstorms will be possible over north Devon, the Pennines and SW Scotland during the afternoon/evening hours, and perhaps also a few over Connacht although this risk is much more dependent on the degree of surface heating given proximity to cloud and areas of showery rain at times through the day. There is also the chance of elevated thunderstorms emanating from northern France and/or developing in-situ across the Channel Islands/Cen S and SE England along the instability axis during the overnight period as mid-level vorticity from earlier French convection arrives from the south, but confidence in much activity here is rather low at the moment and so have refrained from including this risk for now. © Convective Weather 2023 | All rights reserved formerly

Aye was just about to post

Meteoweb post earlier

Lovely stuff

PMSEs don't always correlate with NLCs as the radar echoes record the free electrons that accumulate on the ice crystals that make up the NLCs. These ice crystals can drift in winds and apparently NLCs are not detectable after sunset anyway. http://www.leuchtende-nachtwolken.info/vorhersage.htm Info is here under the OSWIN section

very favourable for NLC development looking at this for today, could explain the decent display elsewhere!

May have to stick the camera out but the North Sea cloud has decided to return and might make a good job of bottling it

Lovely display at Flensburg