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Model Output Discussion 31/05/14 onwards.


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Posted
  • Location: Camborne
  • Location: Camborne

    The ECM ens anomaly building a stronger ridge mid Atlantic giving a more settled, quite cool,  surface synopsis.

    post-12275-0-39069500-1403470567_thumb.p

    post-12275-0-55550500-1403470574_thumb.p

    post-12275-0-72865000-1403470581_thumb.p

    post-12275-0-66063400-1403470588_thumb.p

    Edited by knocker
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    Posted
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet
  • Location: Leeds/Bradford border, 185 metres above sea level, around 600 feet

    A loose consensus between the GFS and Euro at day 8 with the UK in a slack pattern.

     

    Posted Image

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    Posted
  • Location: Weston-S-Mare North Somerset
  • Weather Preferences: Hot sunny , cold and snowy, thunderstorms
  • Location: Weston-S-Mare North Somerset

    GFS shows the weather turning unsettled towards the end of the week in the form of showers

     

    Temps will range between high teens and low twenties.

     

    Posted Image

     

    Posted Image

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    Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

    The GFS continues with an unsettled start to the new Month, With Low Pressure over the UK giving very wet/cool conditions through-out, The Jet also diving South of the UK.

     

    Posted ImagePosted ImagePosted Image

    Edited by Polar Maritime
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    Posted
  • Location: Camborne
  • Location: Camborne

    The GFS continues with an unsettled start to the new Month, With Low Pressure over the UK giving very wet/cool conditions through-out, The Jet also diving South of the UK.

     

     

     

    A sign maybe that the Bermuda-Azores high is not making significant inroads north PM. :whistling:

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    Posted
  • Location: Camborne
  • Location: Camborne

    A quick glance at the anomaly charts for beginning of next month. Singing from the same hymn sheet is still elusive.

    post-12275-0-51442400-1403504508_thumb.g

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    post-12275-0-62993800-1403504530_thumb.p

    Edited by knocker
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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    1015 millibars... it may give some thunderstorms but that sort of air pressure is still regarded as higher pressure, even though it may seem to be a trough. 1010 millibars or below is better for thundery spells.

     

    not 'seem' it IS a trough

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    Posted
  • Location: st albans
  • Location: st albans

    Knocks - that NOAA anomolys at weekends is pure naefs which will mean it's more like gefs.

    Tonight's will have some ECM adjustment.

    The recent runs are certainly showing us how the higher heights are fighting back against the upper trough. Gfs looks a bit isolated this morning but it's likely they will all ebb and flow a little longer on this one.

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    Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

    ECMWF this morning is showing the Low Pressure to the West much stronger than the GFS, And on a more Southerly track for the turn of the Month, With very strong Heights over Iceland.

     

    GFSPosted ImagePosted Image

    Edited by Polar Maritime
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    Posted
  • Location: Peterborough
  • Weather Preferences: Snow and frost in the winter. Hot and sunny, thunderstorms in the summer.
  • Location: Peterborough

    ECMWF this morning is showing the Low Pressure to the West much stronger than the GFS, And on a more Southerly track for the turn of the Month, With very strong Heights over Iceland.

     

    GFSPosted ImagePosted Image

     

    On the other hand, if that were to verify (ECM), then that low will struggle to push into the UK from there, all the hallmarks of it stalling and sinking southwards. Days 9/10 are warm/very warm for the UK under southerly winds with heights building strongly over Europe.

     

    On the other hand it will be completely different this evening as the models have been hopeless at 56 days out, let alone anything in week 2.

    For example

    Day 5 chart from yesterdays 00z run

    Posted Image

    Low pressure pushing through the UK, pretty wet with showers or longer spells of rain.

     

    Today

    Posted Image

    Low pressure much slower and weaker. Going into northern France and mostly missing the UK, rainfall pretty minimal away from the south.

     

    Both those charts reflect the major model guidance from yesterday and today. Frankly, the models have been very poor recently.

    Edited by Captain shortwave
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    Posted
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.
  • Location: Derbyshire Peak District South Pennines Middleton & Smerrill Tops 305m (1001ft) asl.

    I understand that at the range im looking at, Detail will change Cap't. 

     

    My interest lies in how the Models handle the up-coming projected unsettled weather at the turn of the Month.

     

    Lots to be resolved with interest over the coming days, But this morning to my eye's, The pattern is slowly firming up, And the trend looks to be ever growing stronger..

    Edited by Polar Maritime
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    Posted
  • Location: Romford, Essex
  • Location: Romford, Essex

    Watching this breakdown with interest. GFS rainfall charts changing every model run (as you would expect!). Is there a chance the lows for the weekend will dive south too CS? Need it to be dry for Chelmsford area Saturday and Sunday due to golf!

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    Posted
  • Location: Reigate Hill
  • Weather Preferences: Anything
  • Location: Reigate Hill

    The trigger for early July appears to be the packet of lower heights situated at D6 over the Greenland/NE Canada area:

     

    post-14819-0-21108800-1403507567_thumb.p  All models agree on this and all develop this feature and send it SE towards the Atlantic.

     

    GEM, ECM and GFS all deal with it differently.

     

    So by D9 ECM has it as a cut off upper low to the west of the UK:  post-14819-0-46160200-1403507679_thumb.g

     

    GEM pumps up this low as it fights off the higher pressure but it remains to our NW (Iceland): post-14819-0-46297500-1403507743_thumb.p

     

    GFS op slower than yesterdays 12z but the lower heights are sign posted UK and it establishes a feed from the NE Canadian area:

     

    post-14819-0-68937800-1403507929_thumb.p  Yesterday at same time: post-14819-0-70044200-1403507949_thumb.p

     

    That system is causing mischief inter and cross model. The ECM solution of an Atlantic trough would be the best scenario but as expected the models edged slightly closer together compared to yesterday's 12z's. Taking a continuation of that trend the trough/LP may be Ireland based?

     

    In the short term the south has a couple more warm days before temps return closer to average or just below for 4-5 days:

     

    post-14819-0-96941600-1403508370_thumb.g  and wetter (8 days totals): post-14819-0-42851200-1403508390_thumb.g

     

     

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Just looking for this week and the Fax charts are interesting. Met are keeping a surface ridge to the north with frontal activity confined to further south. The change predicted by the anomaly charts and picked up for Wednesday on the Fax charts seems reasonably reliable in the surface pattern now being suggested.

     

    Further ahead, month end and onwards and none of the anomaly charts show great consistency. EC-GFS have changed 3 times in the last 4 days. NOAA 6-10 is less so but even that keeps shifting the main trough 8-15 degrees east/west. So until the anomaly charts settled down then the synoptic models are also going to struggle. My advice is keep an open mind and stop looking for surface detail beyond about Friday. The overall trend from today on is for the weather to become more unsettled, initially from the north (as per the showery band shown on BBC tv charts) but more generally from the west later. The far north may end up the week more settled than further south.

    Edited by johnholmes
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    I too am watching this breakdown with vested interest.

     

    The models don't look good for those in the South West who would love to see a continuation of dry weather (especially those at Glastonbury)

     

    It'll be interesting to see if the GFS pushes the low further South so the UK gets away with a near miss rather than feeling the full force.

     

    Is it likely that the rainfall will be heavy? or are we talking mm's rather than cm's?

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    Posted
  • Location: Darlington
  • Weather Preferences: Warm dry summers
  • Location: Darlington

    UKMO following on from its 12z run yesterday by slowly building pressure over the UK maybe a few showers on the Sunday but for most it would be dry and fairly bright though temperatures would be down compared to late but still pleasant enough given the strong sunshine

     

    Posted ImagePosted ImagePosted Image

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    Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

    I too am watching this breakdown with vested interest.

     

    The models don't look good for those in the South West who would love to see a continuation of dry weather (especially those at Glastonbury)

     

    It'll be interesting to see if the GFS pushes the low further South so the UK gets away with a near miss rather than feeling the full force.

     

    Is it likely that the rainfall will be heavy? or are we talking mm's rather than cm's?

     

    Depends which model you look at. Pressure is never very low, between 1012mb and 1016mb so a very weak area of low pressure. The problem would probably be more that whatever rain is around may take a while to shift. Both the GFS and ECM show the most substantial rain coming late Friday / early Saturday before becoming more confined to the English Channel thereafter. So certainly some rain during the Glastonbury period but nothing too serious at the moment.It's beyond that where some more substantial areas of low pressure arrive off the Atlantic, the first of which shows its hand around 4th July according to the GFS. Just a reminder, we've had an Atlantic low arriving on the 28th June, then the 30th, then the 2nd July and now not until the 4th with the north bearing the brunt. I see a trend emerging here...

    Edited by MP-R
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    Posted
  • Location: Royston, Herts 76m asl
  • Location: Royston, Herts 76m asl

    Depends which model you look at. Pressure is never very low, between 1012mb and 1016mb so a very weak area of low pressure. The problem would probably be more that whatever rain is around may take a while to shift. Both the GFS and ECM show the most substantial rain coming late Friday / early Saturday before becoming more confined to the English Channel thereafter. So certainly some rain during the Glastonbury period but nothing too serious at the moment.It's beyond that where some more substantial areas of low pressure arrive off the Atlantic, the first of which shows its hand around 4th July according to the GFS. Just a reminder, we've had an Atlantic low arriving on the 28th June, then the 30th, then the 2nd July and now not until the 4th with the north bearing the brunt. I see a trend emerging here...

     

    But one of the things I get very confused about in weather forecasting is that sometimes shallow flabby slow-moving areas of LP deliver copious amounts of rain (and not just because they are slow moving - sometimes heavy rain) and sometimes (perhaps more often) they don't.

     

    I have never really understood how a forecaster is supposed to know which scenario occurs, but for this reason, I am not sure that you are right to conclulde that what's coming is "nothing too serious" although it is more probable than not that you are right.

     

    The rainfall prediction models are, at that kind of range, not very reliable in foreseeing this either, I think.

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Any attempt to quantify rainfall totals beyond 48 and even 24 hours is fraught with accuracy issues.

    As to flabby pressure systems that is no guide to whether heavy rainfall may occur or not. Nor is the presence of apparently high pressure. Think back a week or two and the storms that occurred then.

    How does a forecaster assess? Well by looking at every available output, in a 3 dimensional aspect,and using his/her knowledge and experience, even then ending up less right than wrong at times. 

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    Posted
  • Location: Romford, Essex
  • Location: Romford, Essex

    Just desperate for this weekend not to be a washout. Typical the breakdown is occurring this week and couldn't wait a few more days but that's the weather I guess. Models keep pushing things back as suggested a few posts back so here's hoping any rain will be in the form of showers. Question: leading on from what John said about rainfall totals, how reliable are the GFS ones from weather online? Good indication or to be taken with a pinch of salt? Changes every run, obviously.

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    Posted
  • Location: just south of Doncaster, Sth Yorks
  • Location: just south of Doncaster, Sth Yorks

    Just desperate for this weekend not to be a washout. Typical the breakdown is occurring this week and couldn't wait a few more days but that's the weather I guess. Models keep pushing things back as suggested a few posts back so here's hoping any rain will be in the form of showers. Question: leading on from what John said about rainfall totals, how reliable are the GFS ones from weather online? Good indication or to be taken with a pinch of salt? Changes every run, obviously.

     

     

    You answered it yourself really, any outputs from GFS rainfall or indeed UK Met are liable to change quite a lot as the models zero in on T+00. Forecasting the flow at 500mb has always been easier than predicting the surface pattern, which is again easier than predicting accurately the surface temperature which again remains far easier than how much may fall from the sky, when/where/how much. And that is rainfall so imagine the huge issues with deciding will it be snow or rain in winter with another 7 or 8 variables.

    In summary, no, treat any rainfall prediction beyond 48 hours with caution but with increasing confidence as the T+06 time approaches. That is with frontal rainfall which tends to be easier to get the overall spread more correct than that from showers/storms.

    This is not excuses, simply the enormous difficulty in trying to predict moisture content and the precipitation amounts, where and when.

    Eventually I assume the models will be able to do this better than now but it is a hugely difficult task.

    Edited by johnholmes
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    Posted
  • Location: Cleeve, North Somerset
  • Weather Preferences: Continental winters & summers.
  • Location: Cleeve, North Somerset

    But one of the things I get very confused about in weather forecasting is that sometimes shallow flabby slow-moving areas of LP deliver copious amounts of rain (and not just because they are slow moving - sometimes heavy rain) and sometimes (perhaps more often) they don't.

     

    I have never really understood how a forecaster is supposed to know which scenario occurs, but for this reason, I am not sure that you are right to conclulde that what's coming is "nothing too serious" although it is more probable than not that you are right.

     

    The rainfall prediction models are, at that kind of range, not very reliable in foreseeing this either, I think.

     

    I see what you're saying. Needless to say it's these kinds of setups that cause some of the biggest headaches as a number of different scenarios are possible. Indeed, flabby lows, especially involving a warm front coming up from the south, can deliver large amounts of rain. This currently doesn't look likely for the weekend, though it would indeed be foolish to try and predict specifics. One key reason why flabby lows can bring such high rainfall totals is the room for convective rainfall, not just your simple front moving in off the Atlantic which blows through in a matter of hours. Another is when there is quite a stark temperature difference marked by two opposing airmasses, owing to more intense areas of rain where a front sets up shop. This doesn't look likely this weekend.John has pretty much laid everything out 100% there. 

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