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staplehurst

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  1. Mainly after midnight, and moreso towards the very end of the night into the morning 'proper' - though should add this is not a plume event, this is typical autumn surface-based convection over warm seas that then develop more widely inland as surface temperatures warm through the day on Monday. It will be hit-and-miss, not widespread.
  2. The thing to bear in mind about the warnings is that they aren't specifically for lightning, and cover a very large, broad area - their main interest will be the impacts from heavy rain / flooding. Overall the risk of storms has looked highest over northern England today, for the past few days now. Apps should always be taken with a pinch of salt in showery conditions as they will struggle to predict showers in the right place at the right time. On top of the showers being in the wrong place, they also then have to work out whether such shower might produce lightning or not - so you can see how quickly they can become 'wrong' in a forecast sense. Days like today it's always best to follow the radar, and if you have a specific interest in lightning then follow and read the forecasts from the various convective forecasters out there.
  3. We quite often see posts claiming 'we haven't had a storm here in 5 years', 'the south east always gets the storms' etc - so I thought it would be interesting to see just how many days of thunder we've had across the British Isles so far this year (up to the end of June, but in reality there hasn't been any lightning in July so far anyway). This map contains 6 months worth of lightning data, with slight smoothing applied to make it a little easier to read. The white areas signify where no lightning has been detected so far this year. The most thundery places appear to be the Crystal Palace area and Templeglentan (Co Limerick) - both areas have recorded 6 days of thunder so far (a 'day' is considered the period 06z - 06z)
  4. Primarily because there's a strong cap in place the past few days - so strong (and hot) that we set a new record for the highest 850mb temperature observed in the UK yesterday. Pretty much all of the thunderstorms in the past 7 days have been elevated, as you say, driven more by upper forcing than anything at the surface. These can still deliver large hail though, given the magnitude of CAPE and very steep mid-level lapse rates.
  5. Lack of agreement in the models (and still is!) to feel confident enough to include a SLGT last night...
  6. I know not strictly related to convection per se, but related to those tephigrams and the pronounced low-level temperature inversion (essentially a lot of hot air from the Continent riding over the top of a cool undercut) Because the inversion is so low, there is a 'tight squeeze' of the easterly winds flowing over the moors of SW England - this creates a much more turbulent flow on the lee side (so in this case the west side of the moors), where we've seen gusts of 50-60 mph today. These can be quite localised, and hence have a tendency to blow lorries over suddenly etc
  7. Couple of interesting tephigrams from today, showing a plot of temperature (x axis) with height (y axis). Camborne in Cornwall had 2,000 J/kg CAPE at midnight, reducing to nearer 1,100 J/kg CAPE at midday. All elevated above the elevated mixed layer. Incidentally, some very warm / hot air just 1,000 ft above the ground, creating a strong low-level inversion (and hence strong cap). You would need a surface temperature of 43C to break the cap / warm noses though. and this is what 2,000 J/kg CAPE looks like in an environment with no trigger...
  8. yep, Summer Sun posted it last night a few posts up on this page
  9. Look away now - unless you live in Kent of course... 12z AROME fancies a repeat performance of last Tuesday
  10. Very jealous, it's reached 28C in our office so far with condensation on all cold surfaces (such as water bottles). Outside peaked at 26C with a dew point of 20C, which is quite impressive for UK standards. Not pleasant to work in though!
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