22nd into 23rd Aug 2011 - Storm/convective Forecast Discussion And Reports

[Bluebreezer54]

Just had an hour or so of pretty intense rainfall in the Hastings area. Being on crutches prevented me from setting up my measuring equipment in time to catch it, which is a shame because I would think the rainfall rate per hour was quite impressive at times.

[Coast]

a case of should have known better from some of the more esteemed forecasters at the Met and other agencies?

Embarrassed, then over-reacted to the missed forecast for the Bournemouth flooding last week?

[Chloe]

Well what a night/ morning of nothing, well it is drizzling now!

[Thundery Shower]

Can someone here explain why any storms that hit the channel dissipate? back in the 90's through to around 2001 most percentage of storms, would explode into life when crossing the channel and hit the IOW & CS england, iv'e noticed over the last the last couple of years that are chances of any storms from the near continent is very marginal at best, i have the understanding in respect of trough's and spanish plumes. my only opinion is that due to changes in sea temprature and global warming that the trigger of moist air used to produce storms has reduced, thus anystorms that cross the channel losses it's trigger and turns to heavy rain.

[Sprites]

This was always a kent clipper that got over ramped, nothing to do with global warming, global cooling or climate change, sea level rise, freak storms lol

[Thundery Shower]

but main question is why, why is it the head north then veer off NE and dissapate?

[Sprites]

Just the way it developed, Thunderstorms are tricky to forecast, its down to luck if we see any or not.

[<<Ryan>>]

Been raining very heavily for the last 20mins, its flooded ours and neighbours gardens in an inch of water!

Getting lighter now though unforetunately.

[Norfolk Sheep]

I have........light rain.........

[Nick F]

Can someone here explain why any storms that hit the channel dissipate? back in the 90's through to around 2001 most percentage of storms, would explode into life when crossing the channel and hit the IOW & CS england, iv'e noticed over the last the last couple of years that are chances of any storms from the near continent is very marginal at best, i have the understanding in respect of trough's and spanish plumes. my only opinion is that due to changes in sea temprature and global warming that the trigger of moist air used to produce storms has reduced, thus anystorms that cross the channel losses it's trigger and turns to heavy rain.

I don't really think that the cooler sea temperatures have too much influence in the summer over an organised area of storms which cross it, if there is enough instability and lift aloft - storms can continue over the Channel unimpedded - albeit with the bases elevated over a cool and stable boundary layer above any large body of water such as the English Channel. Of course in late autumn and through winter, the sea is often warmer than the air itself, particularly in a polar flow, so the sea becomes the source of energy for storms.

Each thundery set-up needs to be taken on a case-by-case basis as each set-up will differ from another in some way. I think what may have led to the let-down overnight for what was expected by MetO/BBC forecasts to be lots of lightning and flash flooding across the SE, was the low trundling NE over western France ending up with a more easterly component to its track as it arrived across northern France, it was expected by UKmet to be further west across E Channel/far south of England by now. This more easterly shift than expected by UKmet has meant the warm moist plume has been kept on the near continent rather than spilling further NW across our shores. So those storms that were headed north out of France probably run out of juice as the unstable plume remained over the channel, so we have ended up with just bog standard dynamic rainfall rather than storms like the near continent.

Lessons maybe learnt, but forecasting these thundery plumes drifting up across W Europe are notoriously difficult. Hats off to GFS all along, who wasn't interested in creating sufficient instability for storms across England from this set-up.

[Methuselah]

It was always like this, I think. And it always will be? Convective cells form spontaneously, so are always going to be very difficult to predict. So I think that the question: where did all the storms go? will be being asked forever...

[pinball wizard]

Embarrassed, then over-reacted to the missed forecast for the Bournemouth flooding last week?

Looks very much like it. There was never cross model consenus just a risk, nothing more.

[Neilsouth]

Good post Nick F!

TS I really don't think it's anything to do with Global Warming as global temps have actually decreased not increased, besides even an increase of 1C wouldn't have that effect to decay a storm if anything it should increase the chance!. Something however must've changed in our weather because we are have an increase in winter snow spells between nov and early jan and a lack of summer plumes and big storm imports!

[Harry]

This was always a kent clipper that got over ramped, nothing to do with global warming, global cooling or climate change, sea level rise, freak storms lol

There is definitely a question to be answered in respect of climatic patterns...it is as clear as day that the frequency of thunderstorms is lower (in SE England anyway) in the past 10 years compared to the previous 10 years. The number of night time thunderstorms is significantly lower!

Global warming, cooling, climate change....it COULD be any of those. It is MOST likely to be cyclical seasonal patterns which aren't apparent due to limited historical data....if so, then never fear! Thunderstorm rates will be back to 90s standards by the time I'm in my 40s...whoop!

Good post Nick F!

TS I really don't think it's anything to do with Global Warming as global temps have actually decreased not increased, besides even an increase of 1C wouldn't have that effect to decay a storm if anything it should increase the chance!. Something however must've changed in our weather because we are have an increase in winter snow spells between nov and early jan and a lack of summer plumes and big storm imports!

Have global temperatures actually cooled? Or has the rate of warming slowed (big difference between the two)

I hear conflicting 'facts' and so am always a little unsure.

[Neilsouth]

I hear conflicting 'facts' and so am always a little unsure.

So what has changed? CO2 concentrations continue to increase yet temperatures have been falling since 2002? Polar ice is growing. Storm intensity is in decline. One reason may be that solar activity is at the lowest level in almost a Century. link link link See what the sun looks like with and without sunspots link In the past periods with fewer sunspots and lower solar activity were ones with cooler temperatures. It is believed by some scientists that lower solar activity increases cloud formation and this has a cooling effect. If the past is a predictor of the future, these changes in solar activity will cause a 30 year period of cooling temperatures on earth and in fact it appears that this has already begun

Interesting

http://www.isthereglobalcooling.com/

[Coast]

I hear conflicting 'facts' and so am always a little unsure.

I'll also raise my hand at this point and say I did get a little carried away with the possibilities for this very small corner of the SE and my ramping yesterday may have given the wrong impression or aided excitement that wasn't really warranted

GFS was almost spot on and I think that maybe some, including me, were a little too eager to use the MetO and even the NMM output and then try to talk up the GFS which was only ever marginal - sorry!

Anyway, storm starvation does play funny tricks with the mind. I was once walking through a desert, with days of not having had a drink and I suddenly stumbled across a mirage......

So maybe Friday then eh?

[Hurricane Debby]

Well what a damp squib. Most disappointed but really not surprised. Whenever the BBC give a ramped up forecast you just know its not going to happen.

[Neilsouth]

Well what a damp squib. Most disappointed but really not surprised. Whenever the BBC/MET give a ramped up forecast you just know its not going to happen.

Fixed

You only have to remember what the met precipitation models were showing for the south east to see how badly they messed up..... AGAIN

[MP-R]

Well hardly surprisingly - eff all arrived overnight and in fact the country isn't covered in rain either. A dry and bright start here.

I think my eyes are on Thursday/Friday with that trough from the west. Some much cleaner convective weather on the way. As Matt Taylor on the BBC said last night 'slow moving thunderstorms, especially in the west'.

[loopydreamer]

lol! i was up but kind of put my head back on the chair and crashed! hubby found me there this morning!

I cant help getting over excited and hyper!

[Methuselah]

There is definitely a question to be answered in respect of climatic patterns...it is as clear as day that the frequency of thunderstorms is lower (in SE England anyway) in the past 10 years compared to the previous 10 years. The number of night time thunderstorms is significantly lower!

Global warming, cooling, climate change....it COULD be any of those. It is MOST likely to be cyclical seasonal patterns which aren't apparent due to limited historical data....if so, then never fear! Thunderstorm rates will be back to 90s standards by the time I'm in my 40s...whoop!

Have global temperatures actually cooled? Or has the rate of warming slowed (big difference between the two)

I hear conflicting 'facts' and so am always a little unsure.

Well spotted, Harry!

Personally, I don't think that, concerning storms, much has really changed at all . Just that we are undergoing a bit of natural variation, is all. It cannot be average every year.

[loopydreamer]

I'll also raise my hand at this point and say I did get a little carried away with the possibilities for this very small corner of the SE and my ramping yesterday may have given the wrong impression or aided excitement that wasn't really warranted

GFS was almost spot on and I think that maybe some, including me, were a little too eager to use the MetO and even the NMM output and then try to talk up the GFS which was only ever marginal - sorry!

Anyway, storm starvation does play funny tricks with the mind. I was once walking through a desert, with days of not having had a drink and I suddenly stumbled across a mirage......

So maybe Friday then eh?

lol! this made me laugh!!

[Wet'n'Dry]

Is this heavy rain forecast another major fail? So far just a few spits here.

[Neilsouth]

Is this heavy rain forecast another major fail? So far just a few spits here.

Big time!

[Coast]

Is this heavy rain forecast another major fail? So far just a few spits here.

Depends where you are. Eastbourne has had almost exactly what was forecast so far: