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Yeti

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    Model Output Discussion

    in Forecast Model Discussion

    Posted

    I think you have read my post out of context sawel.

    Several days ago I posted as below, but I was told by several members that these models were everything from rubbish to cannon fodder and to stop posting them as I was just trying to wind people up. Needless to say at the time they were showing some of the mildest senarios at 132hrs...whistling.gif

    Posted 22 December 2009 - 22:48

    GME is generally an excellent model out to T+132hrs (it is German after all) and GEM has proven time and time again not only to spot trends but also provide some of the most reliable modelling in the T+120 to T+192hr timeframe. Therefore with respect I am not as you suggest using the least reliable charts to prove a rather baseless point - far from it in fact.

    This post has been edited by Worzel: 22 December 2009 - 22:49

    Interestingly on weather forums in Germany (wetterzentrale forum) and Spain people tend to look at the GEM and GME a lot more than we do - I've always found the GEM a good, reliable and consistent model and it's a shame we don't look at it more often (and no that has nothing to do with today's output! :yahoo:)

    Trust the Brits to favour the American and British models :D

    Model Output Discussion

    in Forecast Model Discussion

    Posted

    Craigers said on last page of locked thread.............

    "GEM is my dream of a chart! which would be amazing for Yorkshire full stop! and with Europe being so cold already, it will deliver with more of a punch than of past years!!!"

    Trouble is the deep cold has been shunted out of most of Europe.... http://www.uni-koeln.de/math-nat-fak/geomet/meteo/winfos/euisoTTPPWW.gif

    6:00 am shows most of Europe marginal with barely a frost.

    Any dry cold to help snow Tues/Wed has to come from the North or from Scandi

    Len

    Good point. Temperatures have risen over 20c here from -16 to 4 in just a few days - the cold spell has gone entirely from virtually all of Europe except the northern half of the UK.

    This would not necessarily be a problem if, like last time, the cold air were to come from the E, as Europe cools down BEFORE the UK in such setups. However cold air is arriving from a *shallow* cold pool over Scandinavia to the N/NE of the UK and Europe should actually cool down after the UK this time:

    http://www.wetterzentrale.de/pics/Rtavn962.png

    http://www.wetterzentrale.de/pics/Rtavn1682.png

    The only potential problem with this is if we see this kind of setup:

    http://www.wetterzentrale.de/pics/Recm2401.gif

    Normally this would bring widespread blizzards along the "battle ground" with a strong SE wind blowing off the continent. However as upper temps tend to be higher in these setups, ground temps need to remain favourable to prevent rain, and if the continent is not cold enough this may not happen. Of course if such a setup occurred later on, like the ECM, there would be no problem, but the UK will probably have to wait until the cold air filters S for widespread low-level snow from a setup like the above.

    Here's hoping the low tracks as far S as possible - this would favour everybody!

    Arctic Temps In Germany

    in Archived weather photography area

    Posted

    Well the cold spell is drawing to a close here tomorrow after a week of consecutive sub-0 maxima. This weekend I have been out to take a few photos near home - firstly of an extinct volcano in the Rhine Valley (Saturday) and then of Ahrweiler (Sunday), a small town about 20 minutes away with a famous wine and liqueur tradition.

    The weather has been exceptionally cold - a cold front on Friday brought sub-20 uppers and that translated to a maximum of just -12.1c here and -11c in Bonn on Saturday. At night temperatures dipped below -16 although other parts of Germany saw clearer skies and even colder minima with -33 reported in one area. The cold was incredible - your nose completely freezes up and more than 10 minutes outside, even with proper winter clothing, is enough to chill you to the bone. :yahoo:

    As for snow, Friday brought light to moderate snowfall for a while but it was proper powder snow falling at those temps, so it accumulated very quickly. Yesterday brought another 2cm so overall about 8cm here which would have been a disappointment had it not been for the extreme cold which made up for it :cray:

    Here is a photo of a nearby road leading to the volcano:

    11145_240273187159_514507159_4348304_4065300_n.jpg

    Inside the crater, snow covers the lava-formed rocks:

    11145_240273192159_514507159_4348305_3914339_n.jpg

    The view towards Bonn, Cologne and Düsseldorf from the top. The shining building contains the headquarters of Deutsche Post and DHL.

    11145_240273207159_514507159_4348306_8024796_n.jpg

    The Siebengebirge, our nearest range of hills, through the vineyards. The Rhine is visible at the bottom:

    11145_240273217159_514507159_4348307_4036845_n.jpg

    The Christmas markets in Ahrweiler - a Dickensian scene!

    11145_240273252159_514507159_4348310_5043937_n.jpg

    11145_240273267159_514507159_4348311_4260651_n.jpg

    11145_240273277159_514507159_4348312_6669714_n.jpg

    It then starts to snow:

    11145_240273287159_514507159_4348313_2470425_n.jpg

    Icicles have formed on the market stalls:

    11145_240273292159_514507159_4348314_4129315_n.jpg

    Enjoy :)

    General Model Output Discussion

    in Spring Weather Discussion

    Posted

    Even with my cold hat on, I think the very cold spell is on borrowed time as next week progresses and the best we can hope for is to maybe buy an extra day or two at the most. It's inevitable that the arctic air will be slowly mixed out from the south, probably by the middle of next week and then the erosion of the remaining cold air further north will continue with the uk in near average temps either by boxing day or soon after.

    It's such a shame - there's such a huge easterly just a few hundred miles to the N!

    http://www.wetterzentrale.de/pics/Recm1681.gif

    General Model Output Discussion

    in Spring Weather Discussion

    Posted

    I notice some ensemble members building HP over christmas, while others keep it rather cold and slack :)

    http://91.121.94.83/modeles/gens/run/gens-5-1-228.png?6

    http://91.121.94.83/modeles/gens/run/gens-0-1-264.png?6

    http://www.meteociel.fr/modeles/gefs_cartes.php?code=7&ech=240&mode=0

    　

    Surprised i haven't read more about this must be bored of the cold weather by now :)

    Actually that's something I had noticed, quite a lot of the models are hinting at pressure and even height rises over Scandinavia later on, and whilst this might not necessarily lead to a full easterly reload it would at the least make the cold air harder to budge.

    GEM: http://www.wetterzentrale.de/pics/Rgem2281.gif

    UKMO: http://www.wetterzentrale.de/pics/Rukm1441.gif

    ECM: http://www.wetterzentrale.de/pics/Recm2401.gif

    As well as the nice GEFS members you posted :D

    Obviously not all of those would lead to cold in the short term but seeing heights and pressure to our NE is rarely a bad thing!

    On the other hand this would need to occur late enough so as not to prevent the Atlantic low moving far enough NW.

    General Model Output Discussion

    in Spring Weather Discussion

    Posted

    Hi again Phil

    Well it's really a complex set up but so much relies on that low to the sw, i really hope it enters the festive spirit!

    Down here is been cold all week and we're now into our second consecutive day below freezing, just shows you with 850's only near -5 what can happen with no sea modification and an easterly flow off the continent. The - 10's are expected later tomorrow so will be interesting to see what that produces, currently -1.7c here.

    The cold is cruel here Nick - temps refusing to get above -3 today, with -9 maxima predicted on Saturday!

    http://www.wetterzentrale.de/pics/Rmgfs574.gif

    That could definitely be one of the coldest days I've ever experienced, certainly at home.

    Sadly the Euros still want to send the low further W atm and so it's GFS/GEM vs ECM/UKMO. Mind you, I believe the 6z was the first GFS run to send the low at this angle? I don't remember seeing it before because a warm up looked almost guaranteed here by next week with no models showing anything more favourable e.g. 6z.

    General Model Output Discussion

    in Spring Weather Discussion

    Posted

    http://www.wetterzentrale.de/pics/Rmgfs634.gif

    That's serious cold in Germany! :drinks:

    The GEM is nice because one of the Atlantic lows instead swings further NE through central Europe and misses the UK, keeping it cooler for longer and if anything dragging down a bit more cold air:

    http://www.wetterzentrale.de/pics/Rgem1561.gif

    There are also suggestions this morning of weak pressure rises over Scandinavia in FI. Tentative, but there on ECM, UKMO and GEM to varying extents - I don't know how this fits in with the teleconnections?

    For example on the UKMO we see a cold pool underneath a HP cell moving SW towards Europe:

    http://www.wetterzentrale.de/pics/Rukm1441.gif

    Model Output General Discussion

    in Forecast Model Discussion

    Posted

    Now if that isn't a snow dome over Bonn I don't know what it is!! :drinks:

    http://www.wetterzentrale.de/pics/Rmgfs72sum.gif

    So disappointing really that despite absolutely bitter temps here, everything is so dry.

    It's encouraging to see the ECM want to maintain heights to our N - the GFS has hinted at this at times as well. That would make it a lot harder for the col air to budge and would delay any breakdown until after Christmas.

    Meanwhile, the UK looks like getting pasted starting Thursday night - so enjoy and let's hope some people see some really deep snow this weekend.

    Model Output General Discussion

    in Forecast Model Discussion

    Posted

    Personally if we're looking for detail over this weekend then to be honest at the moment its a waste of time. Very diffcult to predict what disturbances will develop within this polar flow.

    As for the breakdown thats being discussed. Again personally I feel its a waste of time but I do respect members if they want to look this far. I just can't be bothered at the moment due to the potential over the next few days plus the models will really struggle beyond +120.

    Looks like the cold air is winning on this run?!

    http://www.wetterzentrale.de/pics/Rtavn1501.png

    There is less energy in the Atlantic so the GL HP can ridge S more; there is also more energy in the northern arm of the jet helping the low to dig down S:

    http://www.wetterzentrale.de/pics/Rtavn16216.png

    This in turn though would probably be the death sentence for the block...

    Model Output General Discussion

    in Forecast Model Discussion

    Posted

    Im only discussing what there showing.

    but that is surely in your opinion.i'm all for respecting peoples opinions,but at times this is becomming tedious.

    an ignore poster option would be very handy at times like this.

    There is an ignore poster function, it's somewhere in settings.

    Jed - I think all people are saying is fair enough if it's what the models are showing but if you're going to comment on them then post the relevant charts/data. Posts without given evidence are difficult to follow, look rather too like opinion and are often less convincing as a result.

    Model Output General Discussion

    in Forecast Model Discussion

    Posted

    There is look at the yellow colours, that highlights it well. But notice as soon as thats gone the atlantic starts to make inrodes through the block.

    The colours represent the geopotential heights though at 500hPa so that's not WAA; the yellow would indicate very strong heights whereas the blues show troughs and lows higher in the atmosphere than can be detected at sea level. But yes as you say later on the heights crumble and move west to give a -ve NAO that sets up too far W (current pattern subject to change).

    Model Output General Discussion

    in Forecast Model Discussion

    Posted

    Mate, finding a run that shows no sign of a breakdown early next week is like trying to find a needle in a haystack.. :pardon: The trend has been quickly growing over the last few days for a breakdown, but I do think most models are being a little progressive.

    http://www.wetterzentrale.de/pics/Rtavn1921.png This chart illistrates nicely what would go wrong.

    1. WAA across greenland GONE

    2. Our greeny high slipped too far north west/loosing its grip over the uk.

    3.The strength of the atlantic is unleashed, with no real block in the way there is nothing to stop it bursting through. If we had heights to our north, maybe it could undercut and cause a new block to re-establish itself or pull in a n eastery.

    Chances of a breakdown tue to fri Id put at about 90%, there is still a small amount of time for a change but we need to start seeing that now..

    What's all this about WAA? As I understand it stands for Warm Air Advection - now that happened a few days ago up the Eastern Seaboard as the block was carved out, but for example by the time we reach 120 there's no warm air advection anywhere near GL...

    http://www.wetterzentrale.de/pics/Rtavn1201.png

    Model Output General Discussion

    in Forecast Model Discussion

    Posted · Edited by Yeti

    Just recapping on this post, overnight 2nd/3rd March 2001 the temperature at Cleadon dropped to -10.2C (the only time since I began recording that it dropped below -10C, although 28/29 December 1995 came close). I certainly agree that a sharp frost helps to preserve a snow cover- without a frost there is always the chance of it thawing from underneath in marginal setups for example. That will also be a factor in the upcoming spell of weather because there are sure to be some sharp frosts. Many places that see lying snow on Friday or the weekend may well keep some snow on the ground right through until the breakdown, whenever it occurs.

    I don't think Tyne & Wear/Durham are likely to see much rain or high dewpoints but from the Midlands southwards there would be a risk of that happening on the evidence of the GFS 06Z run. However, having surveyed the evidence I don't think people should worry too much about that run. It's an outlier in the truest sense of the word, and I find it hard to believe that any airflow could spawn that number of shortwaves.

    It's funny you should mention melting from underneath - I'll never forget the disaster of March 10th 2006:

    http://www.wetterzentrale.de/pics/archive/ra/2006/Rrea00120060310.gif

    Heavy snow was forecast for the North for most of the day - however the reality was moderate snow falling all day, settling on the ground for a few minutes before the sludge beneath it engulfed the fresh whiteness. DPs remained just above 0 all day in Harrogate and humidity was high due to the Atlantic air sweeping in on top of the embedded cold. The day was an all-time disappointment and the memory of it has haunted me ever since.

    Those sorts of setups can go either way...

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