john w

lies lies lies and statistics. It is quite amazing how such a topic can cause such grievance, I wonder if the ECMWF and GFS boys have the arguments AND nit picking that has gone on on this thread which has touched elements of science I used to begin to get excited about and I am sure have also caused many arguments in the underworld of professional science. Nethertheless, the forecast and what it entails has to come over the two first lines and for those who think I am having a dig then I am not. I have followed the forecast with interest, great interest in fact. Full credit to MB for willing to test (and if it proves correct) warn some of the danger such an event could have. I am confident that MB, actually, is more than up to accepting false positives and negatives that may or may not come out of this forecast and then use them to refine the method. If youve traded the indices of the world, you learn from your mistakes. On the rest, the method of verification testing put forward by RJS actually seems reasonable, but needs to be done a number of times with different weighting for each of the factors and then a average of the many tests performed....what would be even better would be to acquire the testing and verification maths used to test the global models performance out and apply it to this model...of course there may be a number of variables used in those which have not been predicted by MB...cloud cover, humidity for example. Some interpolation of that may be needed therefore, but I am sure some would agree to do it. Another element I also feel would be good would for another independant on here and I am inclined for a number of reasons towards John Holmes on this...to start to from the event being at +T240...to do a model analysis and forecast based purely on model analysis every 24 hours. To enhance reporting further, we then would be good to have people acquire the METORS from airports and buoy's to verify the forecast. All that would both add to confidence and also presumably the method? On the fluvial systems and flooding quoted in the forecast I only have one slight concern along the lines of what if a fluvial flood occurs as a result of significant catchment wide rainfall as opposed to a tidal surge. I.e if river levels ar high, a surge would be exacerbated even more than if one occured off say a weaker than predicted storm. I was wondering MB if you expected fooding to be worse as a result of both of those factors and if, of course, you will be following the fluvial side of things as well as the sea levels and any surge that may occur. My only other main gripe is in respect to newsworthyness and the 'level' that is applied. Im thinking for this event, it has to be front page stuff but also...has to be reasonable on the agenda internationally. A few high winds in the evening standard I dont think will quite suffice, but then thats the interpretation by me of one test [back to that old lies lies lies and statistics again] Other than that, I think its an extremely novel forecast and one which if it proves correct will certainly get people talking. Personally, I think you would certainly want to predict and test a number more before any method got released and I absolutely see why you would do that. I also wish you every luck. I think i will stay broadly as a reader on this thread but will certainly, as I am sure others will, be keeping my eye on conditions 1-5 of feb. John

Ah that will explain it then...so Im guessing the 2 min 30 one will play on the hour from 00:57 ish...and be similar to the 00:27 one. Then the countdown will commence and story of the hour with a similar irony (albeit on a massive scale - Pakistan floods).

Im surprised by this as it was very different to the 00:00 one...Different language etc, Unless they record several different versions?

My probably last informed post on here tonight. I completely agree that the band seems to have split around the heaviest points on fintensification that were noted in all the warningsand the area is much more widespread. The latest bbc forecast on N24 has all but given up on trying to work on 00:00 to 08:00. starting at 8Am. Im still going for some high spot totals but I think the average will be much less. The odd and I mean odd embedded T-storm, but nothing to write home about. In terms of disruption, I expect there to be flash flooding of areas, but to me this seems much more like a slightly worse than normal autumn frontal system as opposed to a really severe event which on several levels previously looked set to approach July 07 levels. Depending on where people are there will both be upgrade and downgrade elements of tonight. As I finish off the heavier stuff is heading up the M3...South downs and along towards Kent....though not sure Kent will see that much. Currently there is consistant rain, but low intensity of appx 2-5mm/hr. EDIT Forgot to mention the northern band to this...so apologies. I expect this to continue its more North movement as it seems to be diverging from the track of the southern stuff....but I have concentrated so much on the southern element to this that I forgot about the people to the North...sincere apologies. Dont forget the general trend (which at the moment is still well agreed) is a North-West movement. So people to the West Midlands that have yet to see rain should not expect too much from this system. As I finish the edit it has intensified a wee bit..

No offence intended Sam. Personally aviation and then fluvial flooding are my personal interest. The tracking of the main rainband that seems to be laterally affecting the South coast from Bournemouth-poole (meant Portsmouth) - according to raintoday.co.uk will be key. I think spot totals may impress but average accumulations may be short of what is forecast as the area to be affected looks wider than previously forecast. Completely agree with you in meso-scale models though Sam. In hydrometrics (river measuring) the detail and scope that they go to in the US is unbelievable compared to here and thats from a couple of weeks field trip when I was at uni. even now looking at their own services out there they have rain amounts to exceed current flood stages etc. I have a reasonable grasp, but the maths of understanding the theory complicates me when it gets down to the fine detail. Im going for 55mm as the highest spot total to 9Am tomorrow morning for areas where it has passed and thus less than some of the spots recorded in July 07

Fair enough Sam, my bad. Im taking a peek at things from a perspective I guess. I wouldnt pretend to be as qualified or experienced as others in this but I see tonight producing some significant totals that will cause some flash flooding (as manmade drainage systems become overwhealmed...not rivers!!!). I really cant see much convection arising from this, it all seems too saturated and for me the temperature gradients just dont seem to be there. Id be happy to be proved wrong! Interesting to see this is actually passing through quick and whilst earlier I thought this could well match 2007 I am beginning to have my doubts. It has cleared the extreme SW already. Areas around me recorded appz 60mm in July 07 and that does look doubtful now as this system is quite fast moving. Im still expecting some disruption though.

There is so much inter-variability of what people want on these threads which IMO is ever amplified by events like this. The story relating to tonights event will be: 1. The relative non seasonaltiy of it. 2. The rainfall totals and any flash flooding that occurs. The above post, and I mean no offence to this, but as a watch, makes no reference to potentially high rainfall totals and flash flooding that could occur to the south (all the areas under W) which is the real reality of tonights situation. I guess it depends what you are looking for but my cast earlier of the band covering an area more to the East is partly correct, though im incorrect in that the area of risk seems (at least by meto) to be a larger area as opposed to a thin band that has been transferred eastwards. Interestingly, however, whilst it is raining here it is quite light and there is not much of a breeze (Bracknell) so pinning this down to the wort hit area is likely to be difficult as we appraoch a nowcast situation. In 6 hours (roughly) this system is meant to have passed. So if 80mm is still on the cards then some quite impressive intensity is due.

Id be interested to see Village Planks guess on Reading. Im not making any predictions though through I am expecting it to be very wet and for some flash flooding to certainly be a feature of this storm. I do wonder ever so slightly if the main band will shift slightly East...but keep the same orientation, having looked at the latest radars...possibly entering around the bournemouth area but with the same angle of attack then affecting M3/A303, Swindon/Wilts as a West and Surrey/NW Kent as the East...with much more effect over West, SW and NW/NE London.... We shall see and I would be happy to be wrong on this one as the amounts of rainfall look set to be on a par with July 07 event...though often its the direction of travel that can have the most significant impact on flooding. On the hurricane becoming embedded in later forecasts this does seem like a possibility. However guidance on that (and certainly not for this thread) does have difficulty getting this system to turn and become embedded in westerly atlantic flows....at the moment!

Thanks Grey. Im a little new to the whole tropical storm stuff and thought its time to learn, ive only ever really concentrated on air mass and pressure from a now cast point of view. So development is a completely new thing but hey, got to start somewhere and understand all the feedback loops vorticity, shear tropical waves etc etc. Expect some daft questions over the season.

Agree on the development of Celia, convective action through the night should start boost intensification, any likely shear looks set to go away in the next 48 hours and old Blas looks too far away to give any hinderance for development. New to the hurricane watching thread, understand the basics but not the technics and my meto knowledge is mainly UK biased. See you about in the summer

Too far west where I am...nothing as of yet in fact the sky is blue but to the East can see some cumulus uplifting...

http://www.flightradar24.com/ Link to radar, Some airports will still show expected if they believe a flight will depart. There is the chance some craft actually departed before airspace closure and reported an expected arrival. Therefore, they will now fly to alternate or if need be turn back, secure a diversion etc. Glasgow and Edinburgh as I see it are still operational...as much as they can be. Airspace restrictions are from sfc to most flight levels and as such is a total closure, per se....so some routes are not possible across the UK. Nat Tracks - - - > America are deflected south. I note they are now looking at the buffer zone to ash..... Interesting that a couple of BA flights are over the Irish Sea at the moment...test flights maybe...deffo not usual British Airways 'Speedbird' flight numbers as BAW (UNDER ICAO)...sht....INTERESTING,

I have heard that Katla does erupt in a short geologic timescale after the current one. However, short geologic timescale is about as vague as 'in a few centuries'. Looking at the latest chart outputs I wouldnt be surprised to see some of the West coast UK airports closed towards the start of tomorrow, (Cardiff, Bristol etc). The VAAC output also showing parts of Scotland to be affected.

Planes flying across the atlantic fly commonly what are known as NAT tracks. (North Atlantic Tracks) google them, they change every day (6 hours like GFS :lol:) They are waypoints or fixes that planes fly across. There are others across the mid atlantic (South Americal Flights use these) However, there are also actual air coridoors through the South Atlantic as there are a few small islands dotted aeound that can be used. Oceanic Tracks are published. UK controls out to about half way across and quite far south. Half way across its either Gander centre or New York oceanic control. id even post the frequencies if I was sad enough. So planes flying here filed (I presume) for EGLL...what I question is how they got clearence to EGLL from their departure airports when EGLL was closed???? John is right there is normally an alternate and then a second alternate and they are for mainly bad weather at the arrival airport. For air coridoors you need to google upper ATS routes or failing that register at www.ais.org.uk. Go to the enroute AIP and its in there. Youll notice a lot of the airways converge on specific points...that is the start of the NAT tracks and when craft are handed to either Shannon or Shanwick. Hope thaty helps?

Well all seems normal again were it not for the stuff above. A number of routes go West aloft gloucester. So maybe it just seems more as the skies have been empty for a long time. Interesting how many positioning flights are occuring looking at the radar too. As for the volcano, not sure it will spew much more out. As for Ash...Money Won

I agree entirely PIT. Its very very odd as I see it. Those long haul flights would have left some 8-10 hours before they were at Heathrow. Time zones makes no difference, it still takes 10 hours to fly. So they were supposedly departing Vancouver (where one came from) ay mid-day our time. Now what sparks me as odd is how they ever got clearence to depart. I suspect the only way they wrangled it was by setting Glasgow or Madrid as their alternate airport as opposed to perhaps Gatwick or Stanstead (which is the more usual choice but not always). Your correct once at London the aircraft would have been held by ATC as below 20,000 ft space was closed. However at that point the pilot would normally consider the alternate airport. That obviously did not happen. The pilots would have known some back room deals were going on. Its odd, very odd. If anyone was listening to ATC last night they would have heard some interesting traffic I am sure.

On some points above, Noise: Between 11PM and 5AM there is essentially a maximum amount of noise that is allowed, not a maximum number of takeoffs. In other words they allow for examble 1000db of noise from departing aircraft and 1000db of noise from incomning aircraft each night. If each plane send out 100db then that is 10 flights in and out. Obviously those are not the limits but that is the idea of how they work. It begs the question...as planes get quieter the number of flights technically can increase. With BA last night that their long haul flights were in Class A above 20,000 with flightplans to egll egkk etc but at their point of departure some uncertainty about clearence in to the airports. They were subsequently put in to en-route holds and told to wait. So you have a number of aircraft above london holding and waiting, no wonder they opened up on the new advice. On ash, time will tell I am sure. One test flight wont render the exposure that 10-15 flights through the ash would experience. Still at least work will be normal

Yes more lava I think generally means less ash. Will it sit still and quiet once the ash has bubbled out. Has anyone in the south of the UK noticed any ash from this, There has been a dusty mirk on the car but I think it is a mixture of pollen and just general dirt...it has been quite dry down here for a time.

I noticed the moon too...not sure if it is beacuse it is setting, Im hoping its the ash :)

Great link PP. V interesting. Dying down now according to a number of reports. Hopefully stuff will resume to normal soon. Unsure what the FAA in the US will do this this. Would be interesting to see comparisons if they do decide to act and how.

There may be clearence of Ash, note a live press conference from the commission right now. Again as I reiterated, I am not sure that restrictions will be lifted by these test flights. Imagine the calls for corporate manslaughter if a plane were to suffer at the demise of ash. Still a pleasent few days off for me, Im glad im not at work while this is going on. WRT Katla I have a friend who did a Phd on Eyjajallajoefokul and relationships with Katla and She didnt seem too convinced this time that Katla would go up as the seismic activity is not intense enough. Considered that activity may be basaltic magma now moving as a result of pressure changes from glacial melt...or even could be glacial tremors rather than earth tremors.....so just another match in the mix.

Without going in to it too much it woulod be very very difficult for a commercial airline to achieve it in the UK under VFR and in anycase uncontrolled airspace and I think it is also against ICAO rules to even try.

V good point Kate Mart, The routes in to and out of most UK airports are over very urban areas. I can be reasonably confident in suggesting that ATC services will not be provided if met office advice on dust recommends that aviation is not safe. No matter what the airlines want. Will be interesting once it all starts up again, will take a while to clear the backlog

Problem with the radar sites is they are not officiel, people connect up local radars all over the country and it kind of forms a national one...a bigger radar than most ATCO will see actually. Though an ATCO radar will be more accurate. Cross atlantic, yes there are less but the NAT tracks flown do have radar for a fair bit of coverage, the odd remote radar will feed in and of course where air traffic remote radars are, there is unlikely to be an enthusiast with similar kit, per se in the location of some of the remote radars used for ATCO. On to the airliner issue. I would be surprised if allowances are made. But this is unpresedented all the same.

I had 2.5 trips this season and I have to say conditions have been the best I have known. Again very useful commentrs, I would have added my 2 cents worth when I was home were it not for such a busy time at work and home. Next winter...maybe. Hope everyone else had good ski trips....anyone who went last week would have got a late season top up thats for sure.