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    Model Output Discussion 1200 hrs 15/11/14

    in Forecast Model Discussion

    Posted

    http://meteocentre.com/analyses/map.php?lang=en&map=eur_full&area=eur&size=large

     

    Things seem to happen by stealth with an easterly feed as eyes are normally fixed on the atlantic. However at 11Z there is an upper high over Scandinavia of 564 DM. Colder air is flooding out of Russia and across Poland. The easterly feed is modelled to last a few days so it is to be expected that northern Europe will cool down somewhat this week and perhaps provide a source of cold that could with time affect the UK.   

    • Like 4

    Model Output Discussion 1200 hrs 15/11/14

    in Forecast Model Discussion

    Posted

    well this is what the upper air pattern is probably going to look like

    EC-GFS

    http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

    NOAA

    http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

    similarities?

    All 3 show a fairly marked trough, (EC-GFS)=close to/over UK, NOAA further west, Two out of 3 a ridge from northern Europe/Russia out towards Greenland, with EC dropping that idea this morning.

    So not totally clear but the trough over or west of the UK looks odds on which would suggest that the upper flow is going to come from s of west much of the time out to 15 days. Beyond that who knows.

    Perhaps noteworthy that a closed circulation is predicted on both EC and GFS 500 mb heights charts close to N Scandivavia. This appears to be the only warm closed circulation at high latitudes in the northern hemisphere and if correct and if maintained could be the start of a decent block.  

    • Like 1

    Model Output Discussion 1200 hrs 15/11/14

    in Forecast Model Discussion

    Posted

    With an upper cold pool sitting close to the south, 850 mb temperatures around 2 C and surface temps of 8 - 9 C we are currently in a colder interlude before  models predict a surge of tropical continental air to move north from north Africa over the next few days. The warm ridge to the east which has been such a persistent feature over recent weeks giving the UK a warm autumn looks likely to persist and there are hints that this warm ridge may result in a dominant Russian high taking hold. A resurgent  Atlantic will at times inevitably erode the block to the east as shown by this mornings output but at times when the Atlantic flow weakens the Russian high may well extend westwards producing drier, chillier spells.  

    • Like 2

    Model Output Discussion - 31/10/2014 and Beyond

    in Forecast Model Discussion

    Posted

    I just feel that the majority on here are interpreting this so wrongly (and very recent events support this). With a lobe of the PV over N.America bringing cold weather there this is the ideal set up for a conveyor of low systems to develop over NW Atlantic and head for the NE Atlantic where the temperature differential across the N.Atlantic is accelerating the Jet Stream and this will deepen any lows. Something the models proved last December / January that they cannot see very well. There is a slight blocking pattern; but this will be overwhelmed by the low altitude effect of the heat of the N.Atlantic (where SST are anomalously 5C higher than average over Nova Scotia) driving the creation of low pressure systems under the anomalously low temps at high altitude. Its stormy weather not snowy!

    Yes this will eventually likely happen as it normally does but for the next week or so high pressure over Europe and Scandinavis looks more likely to be influential. 

    Model Output Discussion - 31/10/2014 and Beyond

    in Forecast Model Discussion

    Posted

    Generally the trend over the last few days has been for the models to strengthen the block to the NE in the timeframe T+96 to T+144. Beyond 144 models have generally eroded the block, some quite dramatically but each day the back track has continued and it is now looking likely that we will end up with an anticyclonic spell. Warm air aloft being sucked up from the SE could lead to a low level inversion with chilly misty conditions at the surface in an east or southeasterly drift from cooling continent.       

    • Like 1

    Model Output Discussion - 31/10/2014 and Beyond

    in Forecast Model Discussion

    Posted

    sorry what is a closed circulation or is it a shortwave or something?

    http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html%C2'> At any given height level, 500mb in this case, it is where a cut off low or high forms in the normally smooth running contour lines around the hemisphere. It can sometimes indicate a weaker circulation in all or part of the hemisphere and may be more prone to blocking.

    • Like 2

    Model Output Discussion - 31/10/2014 and Beyond

    in Forecast Model Discussion

    Posted

    Picking up from the post by Nick F above and the anomaly charts have been pretty consistent in predicting the pattern shown in the links below. About 4-5 days ago when they began to show the idea of this extended trough into Europe with +ve heights and ridging north of this, see below

    http://www.cpc.noaa.gov/products/predictions/610day/500mb.php

    http://mp1.met.psu.edu/~fxg1/ECMWF_0z/hgtcomp.html

     

    Monday/Tuesday for EC-GFS and the following day for NOAA, so good consistency here which gives a high probability of it actually developing. Just what detail will transpire from this basic upper air pattern is yet to be decided but perhaps not the deep cold some hope for and a few try to make out will happen in the 7-10 day time range?

    ECMWF 6-10 day 500 MB chart is showing a closed circulation to the north of Scotland which is pretty rare and would help to cement the block. Whether it is still there in a day or two remains to be seen but this is significant. 

    Model output discussion 25th Jan onwards

    in Forecast Model Discussion

    Posted

    So despite the 0Z being wildly an outlier the 06Z does produce a cold E,ly in the end.

     

    Shall explain later why I feel an E,ly is on its way and the key period is much earlier around +96 to +120.

    There does seem to have been a subtle trend to a quieter colder spell around this timeframe which has been a recurring feature over the last few days. Are we gradually entering into a change of type 'beneath the radar'. Is the recent short but significant strat warming playing its hand.  

    • Like 1

    Model output discussion 25th Jan onwards

    in Forecast Model Discussion

    Posted

    In 1956, a winter of little promise right up to the end of January - very wet with the occasional tornado making an appearance - we went from this

    Posted Image

    to this

    Posted Image

    From the end of Jan to mid Feb.

    Of course the models now are showing nothing like that on the horizon.....but maybe if they'd be around then they wouldn't have shown that transformation either

    I live in hope that the Fat Lady has only just started on her main course and still has desert to look forward to before she's ready to do anything else.....

     

    A bit like this then;

     

    http://meteocentre.com/analyses/map.php?lang=en&map=eur_full&area=eur&size=large

    • Like 1

    Model Output Discussion 19th January 2014-18z onwards.

    in Forecast Model Discussion

    Posted

    Events do seem to be unusual again this year with weeks and weeks of exceptional storminess and now an apparently immovable trough over the UK and a block of high pressure sitting over Northern Scandianvia of no great intensity but of unusual persistence when compared to the last 25 years or so. The presence of this pattern has caused the cold over Scandinavia and NW Russia to intensify and expand in all directions e.g -15C in Poland this morning. So far the UK has remained on the edge of the cold but as the cold intensifies over Europe there must be at least a worry that this intense cold will very gradually expand further and further west eventually engulfing the UK.   

    • Like 7
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