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staplehurst

Pro Forecaster / Meteorologist
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staplehurst last won the day on June 5 2022

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  1. that was the main reason from refraining going any higher than a SLGT - Lincolnshire saw a number of active thunderstorms develop, and given the environment they had the potential to become severe. However, it became apparent this morning once the earlier rain/convection was further east than generally modelled yesterday that it was less likely severe thunderstorms would develop. It's trying to find the right balance between the chance of something occurring (low) vs the potential for it to be severe/impactful (high).
  2. Shortwave swinging northeastwards this evening/tonight likely to continue to set off random showers/storms for a wee while yet.
  3. Slight concerns about the mass of thundery rain over northern France at the moment, possibly reaching the south coast around 12:30 (give or take). Cirrus ahead of this may dilute surface heating across southern England, and this could essentially eradicate these areas out of the home-grown storm risk. Also concerned about how quickly things will upscale, especially with this mass of rain coming in fairly early. Still think there's a window of 3-4 hours for fairly discrete thunderstorms over the Midlands/western East Anglia, but likely become fairly swamped with rain by early evening the way things are going.
  4. exactly that - at some point there will be a transition, and it's trying to find the location where that happens etc
  5. sadly it was discontinued at the end of 2021 (from memory), but it was generally pretty good at convection
  6. Always good fun when subtle disturbances aloft appear at relatively short lead times - compare the difference over the eastern Channel between the 00z run (left) and the 09z run (right), highlighting some minor PVA in that area (still subject to placement error) aiding the development of the elevated thunderstorm over West Sussex. Incidentally, there are growing hints at an arc of elevated showers/storms developing late evening onwards from Wales-Cen S Eng lifting NE through the night to reach NW Eng-Lincs by 06z Sunday - this is ahead of any developments in the Channel/SE. Not nailed on by any means, but essentially given the unstable airmass in place expect the unexpected should any smallscale disturbances occur aloft.
  7. The 05z Larkhill ascent was very unstable, with >2,000 J/kg SBCAPE given projected temperatures/dewpoints this afternoon. However, this is representative of the air across Cornwall by this afternoon (as it continues to migrate west) and profiles will become even drier aloft through the day as much drier air continues to advect from east to west (this is evident in the 09z sounding, with a much larger gap between the red and blue lines). The 09z sounding suggests you'd need 27.5C to get past the surface-based CIN but 28.5C for convection to initiate in the absence of any notable forced ascent. It's quite breezy today, but still potential for a sea breeze to develop just inland from the south coast of both England and Wales, and this may just be sufficient to create some convective cloud and a few isolated heavy showers. Once you get past the surface-based CIN there's no substantial capping aloft so the only thing preventing big storms developing is just simply how dry the airmass is, so it will be interesting to see if anything does manage to punch high enough to produce a few lightning strikes or not.
  8. Yeah, the one caveat about that paper (it's over 10 years old now, based on my final year dissertation in 2012-13) is it was based on idealised WRF simulations to analyse sea breezes and so probably wasn't the best configuration/physics schemes for convection. Would be good to redo that paper someday with more useful physics schemes and a longer time period perhaps.
  9. haha, love that photo - look how high the base is! So, we've surpassed the temperatures required for air parcels to start rising, however they have a lot of dry air to battle, both in the low-levels (hence the high bases) and in the mid-levels. It will take some time for convection to have repeated goes at gaining height, collapsing/detaching, and another tower will give it a go, reach slightly higher, then collapse etc. Eventually one will manage to punch upwards, and given the instability on tap you should be able to see it shooting upwards without needing to timelapse it. The best chances will be where forcing from the low-levels exists, such as convergence zones and/or upslope flow over high ground.
  10. The video you captured as it came ashore was fascinating to watch! There's a whole 60-minute presentation on both the meteorology behind it and the impact at this year's TORRO spring conference being held in Oxford in just over a week's time if anyone fancies coming along - completely free, full programme and to register: The Tornado and Storm Research Organisation (TORRO) WWW.TORRO.ORG.UK TORRO is a privately-supported research body specialising in severe convective weather in Britain and Ireland
  11. Hi all, I've resurrected our Snow Depth reporting tool (was originally made for the easterly in February 2021). It was very popular and hugely valuable back then to see the spread of snow depths across the region, so if possible could you submit a snow depth reading once the snow has ended at your location and then you can see all the other reports nearby too. Thank you! WQ Snow Depth Reports WEATHERQUEST.CO.UK
  12. Just looking at the travel maps and clearly snow having a big impact on some of the routes in East/West Sussex. Who needs radar when you can see where the snow starts by finding the edge of the slow traffic! Seemingly the boundary right now is just south of Staplehurst-Headcorn, for example. Several reports of sleet/freezing rain on the leading edge (suspect some is evaporating before the ground so the radar appears to look heavier than reality on the leading edge).
  13. The 00z Nottingham ascent modified for 23.5C with a dew point of 17C yields 2,000 J/kg CAPE. The 05z Larkhill ascent is essentially saturated through much of the mid/upper troposphere (indicative of the extensive rain across southern England at the moment from higher level cloud) but still yields 1,500 J/kg CAPE with 23C / 17C. It also has a decent southwest flow at jet stream level, which - assuming convection punches this tall - would help vent thunderstorms at anvil level. PWAT of 31mm at Larkhill, weak steering flow, large CAPE and saturated profiles (meaning less rain evaporates before reaching the ground), low cloud bases etc all point to slow-moving torrential downpours and a real flash flooding concern - especially if they occur over an urban environment and/or train over similar areas. This does remind me of 16 August 2020 and 25 July 2021 in some respects, in which there was a lot of lightning detected on radars but visually you didn't see a great deal. We've already reached 25C in East Anglia where some hazy sunshine occasionally breaks through, and there is already a marked convergence zone running from Norwich down to Cambridge and Luton. Once the first cells develop they will then heavily dictate how the rest of the afternoon pans out by altering the environment with their cold pools and outflow etc. Remember, it is only 10z and most storms at this time of year often develop mid-late afternoon and evening, sometimes well into the evening (thinking August 2020). Yes there is extensive cloud, but the models expected extensive cloud and yet still break out a tonne of heavy showers and thunderstorms. And for those in Kent/Sussex and perhaps Essex, there may be even some more activity overnight drifting inland from the Channel.
  14. Models had a good handle on the increase in mid-level cloud cover today, especially over the Midlands and continuing to increase into the evening - e.g. see 15z run of the Harmonie from yesterday
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