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iapennell

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    Alston, Cumbria
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    Weather observing and prediction, Likes extreme weather prediction. Currently studying Accountancy for more money/weekends off!
    Likes walking, photography and visiting friends and family in spare time. A committed Christian with moderate Conservative values.

    Also likes walking, photography, politics and spending time with family.
  • Weather Preferences
    Proper Seasons,lots of frost and snow October to April, hot summers!

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  1. iapennell

    Meto Uk Further Outlook

    @Ice Man 85 In my seasonal prediction I predict unsettled and colder than normal conditions early and mid-May but later in the month a Scandinavian High set-up lasting for a week is predicted to bring some sunny very warm days, but also some chilly clear nights.
  2. Apologies, did you want the rainfall prediction in mm? 85 mm E&W Mean total rainfall for May, please.
  3. I would like to go for a CET of 10.8C for May 2018 with mean total E&W Rainfall of 8.5 cm, if that is OK please. Ian Pennell
  4. iapennell

    Meto Uk Further Outlook

    Looking at the synoptics predicted for the next half-month shows that there is going to be plenty of chilly weather still to come: https://www.metcheck.com/WEATHER/gfscharts.asp
  5. Further snowfalls in the Scottish mountains are likely during the remainder of this month and well into May with chilly showery airstreams looking set to predominate over Scotland for the next fortnight!
  6. Here in the North Pennines we have had four sunless foggy and chilly days in a row, none of the last three days got above 4-5C, today we reach 7C. Still foggy! There are still quite big snow-drifts (i.e. over five foot depth) from last month's blizzards on the higher fells. Fields finally starting to turn a pale green having been pale-brown since the snow-cover thawed on 22nd March.
  7. (continued from above) May is likely to be quite unsettled at times: High-pressure will never be far from the south-west but an upper trough is likely to be over or to the east of the United Kingdom much of the time. This translates into depressions moving south-eastwards from north of Scotland towards Denmark and Germany; this means chilly showery (but not strong) north-westerly winds. Showers will occur widely across the United Kingdom on most days, though the main consolation will be stronger sunshine between showers. Thus maxima of 15 to 17˚C could be expected in the Midlands and South of England but nearer 13˚C in the North East and Scotland. However, showers will be driven by stronger convection currents due to the strong sunshine and will often be heavy, particularly just inland and on the windward side of upland areas: This means that places like Manchester, inland Cumbria, parts of North Wales, around Glasgow and Edinburgh will be at risk of especially heavy showers accompanied by hail and thunder. In Scotland, even in the lowlands sleet and hail will accompany the heavier showers and snow will fall in the mountains. At night, skies are likely to clear inland and thus night frost will remain a continuing threat for gardeners and horticulturalists alike even in the South. At some time during early or mid-May, high-pressure is likely to build over Iceland and Greenland leading to a few days with colder northerly winds following the passage of a depression towards Denmark. During these days, winds will be fresher, and colder and daytime temperatures will drop to 12˚C in the Midlands and South but nearer 9˚C in lowland Scotland and the North East of England. This will bring the focus of showers to the east of Scotland, Yorkshire and North East England and it will be drier and brighter in the Midlands and North West of England, though the odd heavy shower will still occur in those regions. These northerly winds will turn the showers wintry in Scotland and the North East, though hail is likely to accompany showers further south. Uplands in Cumbria, North Yorkshire, Northumberland and Scotland (above about 600 metres) will see fresh snow-falls establishing a snow-cover and Snowdonia on North Wales will also have snow falling and lying on the very tops. Clear skies at night during the few days with cold northerly winds falling light inland will lead to air-frost from the Midlands northwards and widespread ground-frost even in southern counties of England and in South Wales. Parts of Scotland will have minima below -4˚C. During the last fortnight of May, the slack circulation and cool seas around and to the west of Britain is liable to result in another fine spell with high-pressure across the country. Often high-pressure forms near Scandinavia at some time during late May, and I am confident with cooler than normal seas in the Baltic and around the UK and with global-scale factors favouring a very weak upper-Westerly pattern by late May high-pressure will form a wide ridge extending north-east from the Azores across the UK to Scandinavia whilst the trough associated with the four-wave upper-air pattern is pushed into Central Europe (where it will bring showery thundery conditions). This fine spell is likely to last a week with clear sunny skies and light easterly winds across the country (the centre of the high-pressure will probably be across the northern half of the UK). Unlike the late April fine warm spell this late May fine spell will be across the entire country, only the Orkney and Shetland Isles liable to see some cloud and rain during this period. Some low cloud and sea-fog is liable to plague the East Coasts of Scotland, North East England, Yorkshire and East Anglia at times and this will keep temperatures at around 14˚C by day along the East Coast whilst maxima will be similar across the Orkney and Shetland Isles. Inland and near the West Coasts of Scotland, England and Wales, along with Northern Ireland fine sunny and very warm conditions can be expected by day with maximum temperatures reaching a hot 25˚C in the Midlands but temperatures over 20˚C will be experienced in most locations. Clear skies at night, particularly with drier ground in the Midlands and South of England will lead to rapidly falling temperatures with minimum temperatures dropping to the region of 5˚C or colder over a wide area. Ground-frost will still occur widely and even air-temperatures are likely to fall below 0˚C in some of the Scottish glens and frost-hollows in northern England. Eastern coastal areas of England and Scotland will have cloud and sea-fog at times and this will prevent any frost in these locations. Coastal areas of Wales and South West England will also escape night frosts during the late May fine spell. Following this late May fine spell, high-pressure is likely to collapse over Scandinavia and retreat to the west of Britain to allow a return of cool showery north-westerlies across the country; however the Midlands and Southern England along with South Wales will continue to experience a good deal of bright dry weather and showers will be lighter. Temperatures will continue to reach 18 to 20˚C by day in these areas. Further north the winds will be fresher, the cloud-cover greater and showers heavier, maxima in lowland Scotland will be around the 14˚C mark. Snow will still be possible in the Scottish mountains. However a bit more cloud cover and north-westerly breeze overnight will prevent temperatures falling much below 7˚C across most of the country and this will bring an end to night frosts in most areas. Average daily temperatures for May 2018 will be near 11˚C in the South and South-East, 10˚C in lowlands parts of North West England and 8˚C in the lowlands of northern Scotland. It will be a colder than usual month everywhere except in the far south with departures from the average being 2˚C in northern Scotland. Rainfall will be near average in the Midlands and South of England with 6 to 8 cm rainfall during the month; above average rainfall can be expected in the northern Regions of England and in Scotland with rainfall totals likely to be over 10 cm over a wide area. The incidence of late frosts at night will be well above the normal for May and they will be a serious problem for gardeners in Scotland and the North of England. June will continue with some of the features of the weather during May, at least until mid-month. In meteorological circles, there is a weather-related feature of the climate of this country called the “Return of the Westerlies”, which is related to the large-scale circulation changes that happen over the Indian sub-continent as the Monsoon circulation sets in. Strong westerlies that impact the high Himalayas and Pamirs (removing excess Westerly momentum from the Northern Hemisphere atmospheric circulation) ease during late May and early June- by mid-June these Westerlies over the Himalayas have gone altogether. The air over the Tibetan Plateau becomes very warm for the elevation under the impact of almost-overhead sunshine by this time- leading to the creation of high-pressure aloft and the nudging of the Circumpolar Vortex more onto the Canada/ North Atlantic side of the Arctic. This in turn encourages low-pressure in the North Atlantic which move eastwards towards the UK and this process will be helped by a reduction of sea-ice and warmer waters than usual around the Bering Strait and cooler than normal waters in the North Atlantic and in parts of the Norwegian Sea. The first half of June is likely to see high-pressure to the southwest of Britain nudge north-eastwards over the UK for a few days to bring some fine warm and sunny weather. Temperatures are again likely to be hot inland with maxima reaching 26˚C locally over the Midlands and the South; elsewhere it will still be very warm with maxima widely above 22˚C across northern England Wales and Scotland. Clear skies at night will lead to temperatures falling below 10˚C but frost should not be an issue anywhere except possibly in some Scottish glens or upland valleys in northern England. The fine spell is not likely to last and most of the first fortnight of June will, in the main, be dominated by a chilly north-westerly airstream that will bring showers, some thundery, to most places. The south of England will escape the worst of the showers and here long spells of strong sunshine will nudge maximum temperatures towards 20˚C. Further north it will be cooler with maxima around 16˚C in lowland Scotland and North East England. Eastern inland locations will be closer to the European trough with frontal influences pushing down the North Sea so heavier showers with hail and thunder will be likely to occur in the Forth-Clyde Valley of Scotland, North East England, around Leeds and Sheffield and the Lincolnshire Wolds and thundery conditions with heavy showers may also get as far south as the South Downs of Kent. On the whole southern counties of England will escape the worst showers. Heavy showers are also likely to affect inland parts of the North West of England, such as around Manchester and in the Lake District. Again, night skies will tend to clear inland and this will lead to temperatures falling to about 7˚C in the South, but 5˚C in Scotland and the North where very localised ground-frost will still be possible. However the likelihood of any frost in the south of England will be almost non-existent by early June. During the first half of June, there will be a few occasions with more general cloud and rain associated with depressions pushing south-east into the North Sea. The rain will be heaviest in Scotland and northern areas of England but lighter in the Midlands, the South West, Wales and southern England. Even so, at such times temperatures by day will not exceed 15˚C anywhere and maxima will be nearer 10˚C in Scotland- where June snowfalls are possible in the mountains! During the second half of June, with any high-pressure near Iceland likely to vanish whilst the subtropical high-pressure belt strengthens over the Iberian Peninsula and the Azores, the weak depressions are likely to pass from south of Iceland more towards Norway than south-east towards Germany. Less cool but wetter Westerlies will affect the United Kingdom, with frontal passages affecting the whole country. There will be spells of rain, which will once more be heaviest in western Scotland, North West England, Northern Ireland and North Wales although even the South West of England and South Wales will also get drenched at times. The Midlands, Yorkshire, coastal North East England and South and South East England will escape the worst of the rain: Any rain in the Midlands and South will be welcomed by farmers and gardeners because we may well be looking at water shortages in some of these locations by late June! Brighter and warmer conditions will be frequent in the South and Eastern counties of England where temperatures may reach 24˚C on some of the warmest days. That said, for Scotland and the North West of England daytime temperatures will struggle to top 18˚C on most days. The only real positive is that increased cloud cover at night, especially across the northern half of the UK, and with a less cool westerly airstream will spell the end of any possibility of frost at all during the second half of June. Nighttime temperatures will be unlikely to fall below 10˚C anywhere, even in the lowlands of the North of England and in Scotland. High pressure over the western Mediterranean will nudge northwards to bring a spell of warmer brighter weather to the southern half of England for a couple of days during late June. This will bring daytime temperatures up to 25˚C over parts of the Midlands and southern England and some humid nights. However this spell of weather will not last and Scotland and northern England will remain cloudy damp and cool with a south-westerly wind whilst the South enjoys this brief spell of humid warmth. For June as a whole, temperatures will average about 15˚C in southern England but nearer 12˚C in the lowlands of Scotland. Average temperatures will be close to the seasonal normal for June in the Midlands and southern England but around 1˚C below normal in Scotland and northern parts of England. Wales and Northern Ireland will have a slightly cooler June than normal. Rainfall will range from near-normal in the Midlands and southern England but June will be a little wetter than usual in almost all northern England, Scotland, North Wales and Northern Ireland.
  8. SPRING/ EARLY SUMMER 2018 WEATHER PREDICTION Apologies that this is a bit late, I have been busy during the worst blizzards to hit northern England in the last 39 years: However, I now have my seasonal prediction for Spring, covering late March, April and May 2018. Given this is so late I will add a prediction for June! At the time of writing the Circumpolar Vortex and Stratospheric Westerlies around the Arctic are much weaker than normal and are predicted to remain so for the next three weeks. Almost all (20 of 21 modellers) predict the Stratospheric Westerlies to remain weaker than usual for the next three weeks (https://www.weatheriscool.com). The predictions on some days for the Stratospheric Westerlies at 60N, both at the 10 mb and 30 mb level, show a negative speed, in other words mean easterly winds. This has implications for the weather for up to a month beyond the end of the forecast period for weather-patterns in the lower atmosphere. In other words, we are looking at a situation whereby there is likely to be frequent high-pressure over northern Scandinavia and over Greenland through the remainder of March and for much of April. The pattern of sea-surface temperatures is also interesting. After a cold February and early march sea-surface temperatures around the UK are about 1C below normal for the time of year. There are colder than usual waters in the southern Norwegian Sea and in the North Atlantic around 50 to 60N and to the west and NW of the UK. Meanwhile warmer-than-usual waters (with anomalies over 3˚C above normal) are found off the east coast of the USA. Significantly warmer than normal waters (anomaly up to 2˚C), are also found in the Bering Strait and Barents Sea. The Mediterranean Sea overall was about 1˚C warmer than normal for mid-March. Arctic sea-ice has been at record lows for early March in the Bering Strait around Alaska and in the Barents Sea and around Spitzbergen, but sea-ice extent has been close to the mid-March norm off eastern Canada, around Greenland and just north of most of northern Russia. There was more sea-ice than usual for mid-March in the Baltic Sea between Sweden, Finland and the Baltic States. The Quasi Biennial Oscillation is strongly easterly at the 30 mb level over the Equator and it has also turned easterly at the 50 mb level. The Sun is now very quiet, with few solar flares and sun-spots predicted over the next thirty days. Both these factors signify weaker Westerlies in higher latitudes than normal. In the eastern equatorial Pacific sea-surface temperatures are locally more than 1˚C below the long-term norm so we have La Niña conditions and sea-surface temperatures over all equatorial ocean surfaces are (on average) fractionally below the seasonal normal. The impact of the Madden Julian Oscillation, a convective large-scale weather-pattern that encircles the globe is diminished by La Niña. The Madden Julian Oscillation leads to large-scale convective waves that penetrate the Stratosphere and which can often disrupt the Stratospheric Circumpolar Vortex in high latitudes, La Niña often (but not always) prevents this happening. However, by May the Stratospheric Westerlies at high latitudes tend to break down and reverse due to the 24 hour solar- heating effect on the Polar Stratosphere so the workings of the Madden Julian Oscillation and the effects of La Nina become much less important. For earlier in the Spring, the starting point is very weak Westerlies both aloft in the Stratosphere and in the troposphere at higher northern latitudes. In late Spring the Circumpolar Vortex weakens anyway, though factors such as a quiet Sun and easterly QBO high over the Equator would, if anything, point to even weaker Westerlies aloft but the impact is not as great as during winter and early Spring. The patterns of sea-surface temperature, sea-ice cover and less thick ice than normal over the Central Arctic Ocean (https://www.nsidc.com/arctic-sea-ice) would suggest weaker baroclinicity in the troposphere around the Arctic but with the Vortex shifted a hundred miles or so in the direction of Europe. This will be important later in the season when other global influences, such as La Niña or the easterly QBO have less of an importance. Most of the equatorial waters being slightly cooler than normal, would hint at a weaker global circulation (though the impact on the winter hemisphere would be greater), with a predisposition towards blocking in high latitudes. We can now use the above information to make a forecast: Starting with the second half of March the above analysis indicates further periods with strong blocking patterns over Scandinavia leading to further very cold easterly or north-easterly winds with the air originating over north-west Russia. These will bring snow-showers to the North East, Yorkshire, East Anglia and the South East of England whilst frontal influences bring some heavier rain or snow to the South-West. Eastern Scotland will also get snow-showers, however amounts will be nothing like we saw at the start of March. Western Scotland, NorthWest England and the English Midlands along with much of Wales will be drier and brighter during the cold easterly/north-east spells but still cold. Daytime maxima will range from near 7˚C in the south of England to 2 to 3˚C in North East England and Scotland though upland areas in Scotland will remain below freezing-point by day during these cold spells. Frost will be widespread at night during these cold north-easterly spells as skies clear inland, minima will be locally -5˚C or colder from the Midlands northward. A brief milder spell with south-westerly winds will occur around the 25th March. This will bring rain (and mountain snow) to Scotland and NorthWest England along with parts of upland Yorkshire and Northumberland and North Wales. Coastal and upland gales are possible in all these regions. Northern Ireland can expect similar weather. Daytime maxima will be near 10C in the lowlands in these more northerly areas. For the Midlands, the North East lowlands, lowland Yorkshire along with eastern and southern England and South Wales brighter warmer weather is likely with less rain, temperatures of 14 to 15˚C can be expected quite widely and nights will be frost-free for a time. The very end of March will see a return to icy north-easterly winds with snowfalls in the North East, Yorkshire and eastern Scotland, drier brighter conditions elsewhere and the return of air-frosts at night. March looks set to be the coldest for five years with mean daily temperatures around 3.5 to 4˚C over much of England, averaging over 2˚C colder than average. The departures from normal look set to be about 2˚C below in eastern Scotland; but nearer 1˚C below in western Scotland. Rainfall looks set to be above normal in East and North East England, South West England and in Eastern Scotland but a little below normal in the West Midlands, North West England and western Scotland. As we head into April we can expect the alternation between icy north-easterlies and milder showery westerlies to continue. About half of early and mid-April will be dominated by westerlies with depressions taking a track just to the north of Scotland and moving east into the North Sea. A good deal of cold wet showery weather will affect the northern half of the British Isles, with showers in Scotland and northern England likely to be accompanied by sleet or even hail at low levels but with snow in the mountains above about 600 metres. Strong westerly winds will affect coastal areas of the NorthWest, North Wales and Scotland with gales possible in some places. Daytime temperatures will be near 10˚C in the northern and Scottish lowlands, possibly a bit more where the Sun comes out. There will still be the possibility of frost at night as the generally cool showery Maritime Polar airstream will lend itself to frequent clear skies inland with winds falling light. The Midlands, South Wales and the South and East of England won’t escape showers during the showery cool Westerlies of early-mid April, but they will be lighter than further north and there will be more in the way of sunshine. Daytime temperatures of near 14˚C can be expected to occur quite widely, so it will feel like Spring at such times. Clear skies at night will lead to temperatures falling close to freezing point and sharp ground-frost will occur. During the first three weeks of April, quite possibly as an extension of the cold north-easterlies expected to set in at the end of March, there will be a spell of five or more days when strong high-pressure over northern Scandinavia and/or near Iceland will lead to much colder drier east or north-easterly winds affecting the country. This will bring what is widely known as a “Blackthorn Winter” as it coincides with the time when blackthorn trees normally blossom, at least in the lowlands of the Midlands and South of England! The North Sea will be near its coldest by this point and with the air bring slightly less frigid coming across from northern Russia convective snowfalls near the East Coasts of Scotland, North East England, Yorkshire and East Anglia will be less (and less intense). Alas, there will still be snow-showers in most of these locations but except on higher ground in the North and Scotland will be unlikely to lead to significant snow-cover. Coastal Kent and around London is likely to see any showers fall as rain or sleet as the north-easterly winds will just not quite be cold enough to bring snow. On the western side of Scotland, to the west of the Pennines in North West England and across the Midlands, Wales and southern England the cold north-easterly winds are likely to lead to dry, bright conditions although the north-easterly wind will still feel cold. Again, the South West of England is likely to be affected by frontal systems moving into the Bay of Biscay whilst cold north-easterlies affect the rest of Britain which will lead to some rain and sleet locally, though snow will still fall on Dartmoor and Exmoor. It will be cold nationwide with maximum temperatures below 8˚C even in the South during the April spell with north-easterly winds. Daytime maxima in the lowlands of North East England and in Scotland will be near 5˚C and will remain below 0˚C in the Scottish mountains, where snow is liable to accumulate where it falls. Night skies will be clear during the spell of icy north-easterlies, except along the East Coast and in the far south-west so nighttime temperatures on the coldest nights will drop well below freezing point, particularly as the wind will fall light inland. Again minima below -5˚C will occur locally from the Midlands northwards, so gardeners beware! The cold snap will not last beyond a week and will be superseded by a return to milder showery west or south-west winds. During the last ten days of April there is confidence in high-pressure developing over the UK for a time, aided by the still cold seas around the country and the weakening of the Circumpolar Vortex as this retreats northwards. This high-pressure is likely to be centred over and to the west of the country extending as a ridge from the subtropical-high over the Azores. The vast bulk of England and Wales will enjoy fine sunny conditions for a few days; with temperatures reaching a very warm 20˚C or above inland, although coastal areas will be considerably cooler. Clear skies at night with light winds will still allow temperatures to plummet and frost is likely inland, even in the South. Scotland and the far North East of England is liable to miss out on this fine spell to some extent, chilly north-westerly winds will bring more cloud and a touch of rain to coastal areas. Temperatures in lowland Scotland will remain below 14˚C during the fine spell further south. Clear skies inland at night will still see temperatures fall below freezing-point locally. The end of April or the beginning of May will see a return to showery west or north-westerly winds across the whole country as a four-wave Circumpolar Vortex gets properly established. These winds will be lighter as the depressions responsible for them are likely to be weak and slow-moving. The air will be cooler than normal for the time of year, thanks in part to below normal sea-surface temperatures upwind so daytime maxima will be no more than 15˚C, even in the Midlands and South whilst maxima of 12˚C will be normal for Scotland and the North where hail and sleet is still likely to accompany showers. Again, the Polar Maritime airstream responsible will mean clear skies inland on most nights; this means widespread ground-frost and localised air-frost from the Midlands northwards. Average temperatures during April 2018 will be near-normal in the South of England but colder than normal elsewhere, with the departure from the seasonal normal over 1˚C below the April normal over a wide area. Mean daily temperatures will range from 9˚C along the South Coast to 7C in the lowlands of the North West and a chilly 5˚C in the north of Scotland. Rainfall totals will range from a little below normal for April in the Midlands and the South of England and in South Wales, to around the seasonal norm in South West and North West England and North Wales but a little wetter than normal for much of Scotland, North East England and Yorkshire. (CONTINUED BELOW)
  9. Unfortunately I do not have the powers to organise the weather, otherwise I would make sure we did have proper seasons. I will get round to posting a spring forecast by next week, so it will be in time for the second half of March, April and May. There are some indications of a few more days with blocking over Scandinavia leading to further cold easterlies during the second half of March, however I will be able to provide a clearer picture of this, and the weather going forward when I have done a thorough analysis of the global drivers. Rather Un weather-related, but still concerning the North West is this Site in which I start a Campaign to get North West Regional Television coverage for Cumbria and Lancashire improved: https://northwestisnorthwest.blog Ian Pennell
  10. And these are some of the conditions we had on higher ground above Nenthead:
  11. Still some big drifts in the North Pennines following last week when we had our most severe blizzard for years. Below is the view in our village of Nenthead, in the North Pennines on 28th February when the daytime maximum temperature was -5C!
  12. There has been a fair bit of snow across Cumbria today, a good number of roads in the Lake District were closed or passable only with care. Despite this being a significant occurrence, which certainly would have affected a number of folk, none of this was covered on BBC North West Tonight nor Granada Reports, despite the fact that South Cumbria receive these programmes! On a slightly different subject, very relevant to much of North West England read this with regards Regional Television in Cumbria and northern Lancashire : https://northwestisnorthwest.blog Ian Pennell
  13. This is the 10mb level Stratospheric prediction on the Weatheriscool website with predicted 14 m/s easterlies on average at 60N. It is predicted for 15th February which is not too far off. Should give some folk some hope that the lower troposphere might follow suit :
  14. @karyo, It does look like the promised easterlies will be materialising over the next fortnight, although rather than being one continuous spell it looks like high-pressure over northern Europe will deliver two or three short spells with easterlies each lasting two or three days. The first of these looks set to occur around 5th/6th February. And this is the forecast chart for 14th February:
  15. @ BFTP, When I make my seasonal prediction I use the global patterns of Arctic ice-cover, Eurasian snow-cover, the ENSO Cycle and the Quasi Biennial Oscillation (the pattern of alternating easterly and westerly winds in the Equatorial Stratosphere) and sea-surface temperature anomalies at the time I make the predictions. Other factors such as Sunspot Activity (the Sun is entering a quiet phase) also have an influence on likely weather-patterns I use my understanding in meteorology (which I studied at university 25 years ago) to put these together to work out the likely trajectory of the prevailing weather-patterns. Conditions around the UK, such as sea-surface temperatures around and to the west of Britain also have a strong bearing on likely weather-patterns going forwards. I also make references to what other professional forecast companies are predicting, and if (say) a number of them predict something significantly different I modify the outlook; I am of the opinion that trusted forecasting companies might pick up something different, like variations in tropical convection- that I might miss in my assessment that could substantially alter the outlook. For the first month into a forecast, I use the 16-day forecast charts, Arctic Stratospheric outlook (which gives a strong indication of conditions for a further two to three weeks' ahead) and I make reference to the Met Office and Accu-Weather extended outlooks and I use that, as much as my own understanding of how all the factors are liable to play out. However, even the Met Office with their super-computers are only totally reliable out to about five days and if you are familiar with the concepts of Lorenz Theory you will understand that small perturbations, such as a depression forming over Newfoundland and racing eastwards can completely alter a weather-pattern over the medium term. However, certain macro-scale conditions do have a tendency to support certain prevailing weather conditions. A warmer than usual North Atlantic with very cold conditions over Canada and Greenland create stronger atmospheric temperature gradients and these would spawn deeper depressions and stronger westerlies coming into Western Europe and these conditions between the North Atlantic and Canada/Greenland were the basis of my prediction that December through mid-January would be Atlantic-dominated but with short cold snaps- which has largely come to pass. I did also predict two very cold easterly-dominated spells for late January and early February on the basis of the easterly QBO, weak Lá Niná, excessive snow-cover over Eurasia at the time of my forecast and a quiet Sun that would lead to a weakening of the Circumpolar Vortex and the strong (baroclinic-related) Westerlies coming across the North Atlantic being pushed back. I don't think this analysis is wrong as there is plenty of evidence that no Sunspots, greater snow-cover over Eurasia and easterlies high over the Equator along with cooler-than-normal Equatorial waters weakening the Intertropical Convergence Zone (and with it lessening the creation of Westerly AAM that fuels the Circumpolar Vortex)- lead to weaker Westerlies and a greater extent of blocking in higher latitudes. It takes a lot to convince me of the likelihood of high-latitude blocking and the occurrence of severe cold in Britain (indeed I did under-estimate the extent to which cold Arctic air would reach Britain during December, even though it was still an unsettled month with storms Caroline and Dylan). The stormy pattern I predicted for early January has merely continued longer than I originally predicted, however that will change as a big anticyclone appears in the pressure charts for ten days' time and the intensity of depressions over the North Atlantic look weaker! As to the reasons for the failure of the late-January frigid spell with easterlies there are a few candidates to blame: There has been a little more solar activity in the terms of Solar Flares that was not anticipated back in November, snow-cover over Eurasia has been pushed back to the Russian border by mild south-westerlies over the continent and the exceptionally cold conditions over Canada and the north-east USA during December and this month have led to a reduced predisposition towards blocking in high-latitudes and a stronger North Atlantic flow than was anticipated by this point in time. However, the Circumpolar Vortex does normally weaken in early February as the Sun returns to the Arctic Stratosphere: As the Arctic Stratosphere warms in consequence that does help tip the balance in favour of weaker Westerlies and high-latitude blocking. I am still confident that this, in addition to the factors highlighted above -snow-cover over Eurasia (which is increasing again), cooler than normal oceanic waters overall and the easterly QBO will be enough to tip the balance at some point in early-mid February. Note too that the Met Office is now predicting " drier spells", "that will be colder" by mid-February in their 16 to 30-day outlooks: See here- https://www.netweather.tv/forum/topic/75951-met-office-16-to-30-day-outlook/?page=70. I trust this helps clarify how I make my predictions and my own analysis of why the January bitter-cold spell -that I predicted back in November-has failed to materialise. Ian Pennell
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