VillagePlank

Yes, there is a potent area of high theta-w at 850hPa appearing in the SE corner about the same time,

It does look unstable, but there's an awful lot of CIN to overcome to tap into that CAPE. A TT of 51 suggest isolated severe storms, I do hope so. Last night I was a bit 'worst-for-wear' so missed it

Something odd on the MetO app tonight for our region. First absolutely nothing, as forecast, Then, all of a sudden (and out the blue) two hours later we are awash with storms -- all apparently home grown. Anyway it seems to coincide with the 10m streamlines (which seems awfully close to the ground to me) but perhaps they're governed by something more exciting higher up,

Looks to have died out just before Maidstone - the other lobe continues NNE, but will miss us here in Medway. Here's hoping for a bit of North Downs orographic lift to help us out a bit! (Convective) wind has picked up a lot, though.

Incoming to N Kent ... E London just sparked off from nowhere, too. (not quite the Medway Sausage (for those that remember it))

Thunder and lightning and rain to my due South. Curiously the western part looks to be going N and the eastern part seems to be going NNE. Some stuff just sparked off in East London, too.

I hope that the forecast diurnal kick thingy-me-bob forecast at approx 9pm kicks in!!

Can confirm that essentially everything here in Rochester, Kent, is tinder-dry - I hope that front heading East doesn't fizzle out before it gets here!!

39degC recorded in Rochester, Kent (103m ASL) - 1degC warmer than forecast Moving car temp with no decimal places, so presumably somewhere between 38.6degC and 39.4degC

Dewpoints back up to their normal stuffy levels, too, by the end of Tues. Looking very uncomfortable indeed, with limited ability to sweat out a reasonable nights sleep!

GFS 12z throws in a couple of 42degC for Tuesday

The effect of heat on the human body is in a large part related to adaptation. That's to say, if you live, work, sleep and play in 35degC all day long, then, clearly, you aren't going to be affected by a 5degC jump to 40degC. However, if you are happily going about your day, with nominally a hot day being 25degC-28degC, the jump of 12degC is going to affect you to a much larger extent.

Or, deserts tend to be full of lots and lots of sand, which heats up much faster than ocean?

Maybe, but the high efficiency of evaporative cooling in a dry environment should mean that any evaporation that happens (there will be some) will readily cool the surface temperatures. If there's none, as you say, no limit. IN a closed environment. That heat is only going one way, up - and there's a nice moist layer at 850hPa to suck it all in. (I'm guessing here) EDIT: if there's less stuff in the air (ie water) there is less to heat and less to radiate and therefore less temperature to be felt (still guessing) ?? Does it all, in the end work out even, so that humidity and surface temperature are not related?

Sadly, soil has a heat capacity of only 1/5th of water - so a moist atmosphere (ie higher dew points) is preferable. 39degC +/-3degC is my guess

It could well be the very low dry DP (given the theta-w's @ 850hPa) at the surface that are restricting the temperatures - on the basis that moist air holds more heat.

From GFS 6z, High 850hPa temps move in properly Tuesday. IIRC 20degC@850hPa was enough to beat the UK record of 37.7deg. 25degC just misses the Kent coast, which implies that the temperatures are increasing as they crossing the UK Using the old rule of thumb of getting the parcel temperature at 850hPa and taking it down the dry adiabat, we get v.close to the record, if not exceeding it Theta-W look very high, too However, surface DP look far too low for any surface based storms at this point - This leads to a forecast of which, as others have said, seem too low.

Yes, feeling quite hot and humid here in Rochester

It does depend if any assumptions exist regarding the distribution of parameter ranges. For instance, if it is assumed that a +30degC day occurs maybe twice/year for London, and then model output suggests that we're looking at a week of such temperatures, then the model output would be modified to better reflect the temperature distribution expected of London. As it happens, GFS *does* do this; it calls them biases I haven't read through them, so I don't know if climate change related parameters are affected, but, one would presume (hope!), that the biases are updated regularly, in any case. If they are updated regularly, then the effects of climate change are baked in. Conversely, if a model doesn't consider input variable distributions (GFS biases) , then it *shouldn't matter* anyway, since most models, right in their core, are a (kind of) solution to the Navier-Stokes equations, where it really doesn't matter what the magnitudes nor distributions of model variables are. I suspect biases in GFS exist to smooth the output to something sensible in the face of computing the weather for an entire planet where incomplete data, wrong, or simply missing data is a real problem.

Indeed. Off the my North West, and not a direct hit, sadly. Hopefully, this one can clear away and surface heating can generate more!!

I say that, and now the sky is very dark and foreboding, and the wet stuff is falling out the sky. Still hope to snatch something from the jaws of 'no-storm-Rochester' yet!

Tomorrow doesn't look so good, either. Perhaps something right into the night, perhaps into the early hours

I'm not convinced. Well, not by GFS 6z, anyway. Whilst it does look like convective weather, and it does look like likely thunderstorms (TT=41) it looks that these will be widely scattered (K=31) - with that, most will miss out, I suspect. No SBCAPE really, and where there is some it is moderately capped, so relying on a cold front for lift, later, to breathe some life into some MBCAPE. AND relying on it not to fizzle out by the time it gets here. Lots of rain in showers that occur, and risk of some strong convective gusts, though. DP are OK, with some humid air preceding before the front, so the game is not necessarily lost just yet, just some caveats. Aside from all that, I know the French gave us 12points on Saturday, but are they generous enough to slide up an export or two?

Trees holding up at the moment here. Haven't yet 'inherited' next-doors trampoline. Expecting strongest winds in the next hour or so.

Yep, doesn't look *at this stage* as if a sting-jet will form, being that the hook around the core isn't defined enough. Satellite pictures depict it looking a bit of a mess, actually. Bog standard explosive cyclogenesis at the moment.