Evening thunder

Been a lot of Ac Cas at times today but some of the most photogenic is now:

Turns out the 30C temps have come this far west after all! I noticed yesterday evening the Met Office map looked promising. Reached 30.4C here, even with a slight sea breeze. That's a new record for my station (beating 30.1C in July 2018). It's possible that's a degree or so over what an official station would record due to the garden fences etc in this wind direction, but then most of us have similar issues. The shaded alleyway was over 29C. Dropped back to 28.2C now as the sea breeze gets more effective. Meanwhile on the North Coast of Devon it's 18C with Sea Fog! Just over the border Bude is reading 17.4C! Doesn't seem to have stopped the beachgoers! I have a feeling they will have expected better. Often they get higher temps than me in heatwaves due to SE winds, but this summer the south coast has often had much better weather.

Lol sounds about right, maybe I'll change my username to reflect something that actually happens Evening drizzle?

Pretty sure that will be correct as it looks like it misses me just to the east... which, coupled with all the storms to my west this morning, will mean I'm about the only place on the South coast to see nothing! Think I'll have to think of a name for this storm free area.

Well the eastern most area of convection completely died (the area you might think new storms develop/intensify). Then all the storms in the SW followed. No sun for 3 hours and this band will last a bit longer going by the satellite, but it's convectivey dead. What's the point of that? Currently 21.4C with a surprisingly fresh northerly breeze gusting to 25mph.. Met Office forecast: A very hot day. Maximum temperature 32 °C". Hmm...

This makes slightly painful viewing (all going NW)

Really kicking off over North, Central and West Devon. They have had most of the surface based storms in the county this summer due to wind direction, and now get all the elevated storms too

Heard a few distant rumbles when I woke up but all going to plan apart from that, i.e passing by me and also developing after me, which was kind of what the forecast models showed to be fair. Had loads of Ac Cas though and a decaying anvil to the west and overhead, can now see the distant CB of the NW Dartmoor storm.

Had barely woken up with not much visible out the window but heard thunder, looked at the radar and saw the storm was to my south moving NW. Heard a couple more but then when it was a bit closer, it was quite active on Blitzortung but interestingly you couldn't hear the thunder much anymore. All has passed by here though with a load of Ac Cas and a decaying anvil overhead, but the sun kept shining throughout. A lovely morning to sit out with a cup of tea... It's 23.5C, 3 degrees warmer than this time yesterday. Although now I see low cloud is very close to my north again.. maybe remnant cooler air from that will put a cap on temps here again, though mid level cloud in some format is more likely to today.

Another very warm day but cooler than forecast despite full sun with a max of 26.8C here at 14:57. A little earlier than I thought it would be, I suspect we were seeing slightly cooler than expected air due to that low cloud that took a while to burn off north of here. Currently 19.9C, different world to Portsmouth Although it's still very warm-hot here, it seems we just aren't going to get enough of a NE-ENE pull here to advect the proper hot stuff you are seeing further east. Boundary will be in Dorset for 6 days in a row it seems! Rare opportunity missed with the offshore winds and kind of a shame to miss out on experiencing/recording that. Though afterwards I'd probably be glad of a cool down and more pleasant mid 20's temps It does seem mission impossible to get past 30C here these days. Oh well, hopefully we don't miss all the thundery activity.

I wonder what the chances of surface based storms are tomorrow? On the GFS at least, very high CAPE, wind convergence, and the precip seems to intensify in the evening. Met Office map suggests stronger cells around then too.. I might have to delve further and see if there's a realistic chance of the cap breaking for surface based storms or just elevated stuff. Or I could just wait for the excellent forecasts from convectiveweather.co.uk Probably the usual elevated activity/cloud complications anyway.. that could also mean I miss a storm here, but as I appear to be off work tomorrow, I might have to consider a chase.

Seems the low cloud has reduced maxima away from the SE (even though it mostly burnt off) compared to many models like the ECM (perhaps an associated stronger low level inversion to warm up too?). AROME model did very well with the low cloud extent and then suppressed maxima when I looked yesterday evening. 19C in Hereford and 21C in Bristol at 3pm, but the ECM had an un-adjusted temp of 28 and 29C at 4pm 24.1C at Exeter Airport, so cooler than forecast here too. Kind of a shame as it might have just about been my hottest day of this spell.. Though it looks like we will be just west of the 30C stuff all through this hot spell! If correct, a very warm-hot spell here but not quite what I'd call an intense heatwave in this location. Hopefully some thunderstorm interest instead (as long as they don't all go around here!)

Here's a GFS temperature chart I saw modelled in 2018 Obviously it was in FI and didn't come off (I remember talk of a big August heatwave), but definitely met the criteria of being saved to my laptop!

Max 29.8c here on the Davis (or 28.9c on a thermometer in the shade) yesterday. Down to 14.1C overnight. Seems clear on the models that the 30C line, and potential 32/33C at times, will be around west Dorset again, and perhaps there until Wednesday! Somewhat frustrating... Although I noticed yesterday the AROME had significantly lower maxima than ECM for us today The extent of the low cloud over much of the country this morning certainly reflects the AROME and not the ECM..

Sunny here with just a small amount of high cloud and reading 28.2C on the Davis. You can tell the airmass is slightly cooler at lower levels this far west, with some places further east in the low 30's despite more cloud. Exeter airport was reading 26.7C at 2pm, yet the Isle of Portland was 28.9C, don't see the latter often!

Yeah it will defo be very warm-hot here (Met Office forecast 27-28C), though I feel it will be hotter further east as the 950/925hpa temps look 3-5C higher. The Met Office has it into the low 30's in Dorset. If things were 50 miles further west we could be challenging records here due to the offshore flow (I think that could be possible for near-south coast locations Dorset eastwards). Might seem silly me complaining about a few degrees, it's just kind of annoying how the boundary at low levels has been slightly east of here in all the record/near record events of recent years. Today was a bit unusual in my location in that despite reaching 27C, we had exceedingly light winds all day and no sign of a sea breeze. Usually it's either a sea breeze or an offshore flow strong enough to prevent one.

I like to use 950/925hpa temps now to better understand potential maxima GFS 925hpa Euro4 950hpa Shows why potential temps are again much lower in Devon than Dorset eastwards, even when 850hpa doesn't show that so much Aaand of course that remains the case tomorrow.. and the next day... like all recent notable hot spells....

I was following that last Friday, Northolt was usually lower than Heathrow, and Iver Water Works lower again (and it's closer to Heathrow). I've actually done an Excel document of maxima at Heathrow vs Northolt this summer and Heathrow's average maximum is 0.76C higher so far. If anyone knows where you can daily figures for stations such as Iver Water Works or Kew Gardens it might be interesting to compare. Not sure if the station enclosure itself fails any siting criteria (though it is bordered immediately to the north by road and carpark tarmac many times wider than the enclosure itself), but in my opinion with the available data, the local environment probably does lead to slightly higher maxima than if it was just grassy fields for example. I mean, I can't think of any local topography that would lead to Heathrow so often being the warmest, compared to the other local stations. There's also the size of the place, The length of the airport is longer than the distance between Heathrow and Iver Water Works. Anyway, I'm not saying we should/shouldn't have a weather station there, after all if we want to exclude all 'artificial' influences then I suppose we should exclude most of London's stations due to the UHI, especially at night..and if I go on any longer maybe it would be better in a separate topic.

Well the sun came out for a bit, and the temp reached a very warm and humid 27.3C. Then elevated showers moved in and produced a nice rumble of thunder (part of it nearly overhead but probably a few miles up), followed by a brief moderate shower that made the ground damp. Radar showed heavier cells towards Exeter but only moderate here so the intensity was similar to what the radar suggested here. Temp now 23.1C, dew point 20.2C (though Davis sensors often over-read humidity/dew point slightly).

A lot of mid level unstable looking cloud today. Cells with sefrics were coming but they just weakened to add to more general mid level cloud and a brief shower... standard. Cloudy here, brief peak of 26.3C earlier before dropping to 22.7C. Currently creeping back up to 24.8C. very light, variable winds and no sea breeze. Would probably be quite hot with sunshine but then something always scuppers it Plymouth is 27.1C lol, surprising how often even there is hotter than here in warm spells. Last Friday had a load of mid level/high cloud at the would-be hottest time of day too. Looks like tomorrow will be into the 30's for Dorset eastwards: I reckon Alderc and Mapantz will be in a good area for that tomorrow even if there's a bit of high cloud. The real hot air not getting west of Dorset, as ever..

At least you are in the area affected by proper heat in the days to come. I see Hurn has reached 30C. The heat boundary often seems to be in Dorset these days, even when not explained by sea breeze or anything, just the edge of the hot airmass often happens to set up there. Even the Isle of Portland that sticks miles out into the sea was just as warm at 25.5C earlier as anywhere in Devon. Tomorrow it's into the 30's easily in Dorset but 27C here on Met Office forecasts. ECM does kind of get the real heat further west Sunday/Monday but that remains to be seen, some models are very consistent with it being east of a roughly Dorset to The Wash line every day. GFS just gradually cools off after tomorrow here, no storms either.

That's more like what I'd expect to see when I look at forecasts for Florida The Met Office map has it above 20C pretty much everywhere in the SE & EA with ~26C in Central London on Saturday... at 4am.

Looks like we will have at least very warm-hot temperatures here from tomorrow into next week. Interesting how many temperature charts I've seen show the real 30C+ heat not getting west of Dorset (even if higher 850hpa temps are further west), reminiscent of many recent hot spells. If the hot air did get further west, given the south coast may see the elusive offshore breeze in a hot airmass at times, we may challenge some local records (Exeter Airport's June/July/August records are from 1976, 1983 and 1990.. with 90F not seen since despite occurring in those 3 years that are 7 years apart). Surely on the ECM the hot near surface air would get into Devon though.. if not I give up on getting proper 'hot' temperatures here again lol.

That's true, if the airmass is slightly hotter, of course the maximum may be slightly higher. Another thing I forgot to mention, I feel like last Friday's large under-estimate may have in part been due to the models predicting more cloud arriving sooner or slightly faster movement of the plume? (UKV from the day before had modelled elevated showers/storms in southern areas in the afternoon, and on the day the GFS 12z had upped temps to 34C) I also noticed a couple years ago the GFS seemed to under-estimate more in breezy conditions than light winds. Not sure how much that is currently the case but I think there was a reasonable breeze on Friday. Yes but surely that would mean higher 850's as well? We do seem to be seeing more incidences of the 20C isotherm making these shores. I'm just saying that although 850hpa doesn't always translate easily to the surface, a think a realistic maximum difference to expect in a heatwave is ~18C and I don't think it will be different this time just because. Happy to eat humble pie though. I'm possibly being a bit pedantic over 1-2C.. I wonder if Saturday could see the highest temp now.. and that makes sense about human input.

Seen a fair bit of discussion about max temps today, more in the MOD thread but I think my post is more appropriate to here. I Must admit, I'd be surprised if we see 37C+ on Friday. 850hpa temps are 17C on GFS & ECM and Last Friday they were 20-21C. Also, ECM has 950hpa temps of ~26C (windy.com).. last July for example they were 31C. All recent record/near record temps I have remembered have had a difference of near 17 or 18C from 850hpa to the surface. Even with a long build-up like 2003. August 3rd 1990, had a 19C difference with 37.1C reached from 18C 850's. So I suppose if we see a 19C difference, and 850hpa temps are 18C.. we may get 37C.. though I think 35C's a reasonable bet, maybe 36C. I've noticed Met Office forecasts for places with weather stations seem to be adjusted a bit higher compared to surroundings.. but Heathrow has a surprisingly high uplift of about 5C in forecast maxima considering surrounding towns such as Staines, Hounslow etc which are forecast 32/33C.