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knocker

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Everything posted by knocker

  1. After another frosty and foggy start, most of England and Wales will enjoy another sunny day tomorrow but approaching fronts will bring cloud/rain to the NW during the afternoon and these will track south east overnight and through Weds, tending to weaken as they reach the retreating high ptessure. Some wintry showers over northern Scotland in their wake and perhaps down eastern coastal regions And once the fronts are out of the way high pressure will rebuild from the west over the rest of the week and through the weekend
  2. And in the ext period there is nothing in the clusters to contradict the impressions given by the means
  3. The medium term anomalies are very amplified upstream with a strong westerly upper flow exiting the eastern seaboard across the Atlantic where it runs around the ever present high pressure in the east. There are still some differences on the orientation of this, , allied to the Euro trough, but generally we are looking at a pretty dry period over much of western europe
  4. Further fronts track south east down the country late Tues through Weds before high pressure rebuilds from the west
  5. The weakening band of rain associated with the cold front is currently over the north of England and will continue to track south through the day, finally clearing the south coast late this evening. Behind the front front clearer and cooler weather resulting in quite a widespread frost Sunday morning. And then once any fog patches have cleared a sunny day in most areas but with more cloud and some patchy rain/drizzle in the north
  6. In the ext period the clusters tend to support the trend indicated by the mean anomalies of a weakening and retrogression of the Azore HP resulting in an Atlantic which is a tad more mobile
  7. The medium term anomalies are still about the structure and orientation of the high pressure and position of the Euro trough which dictates the variation of the detail vis the surface analysis. Likely generally remaining very dry with any unsettled weather running around the northern periphery if the ridge
  8. To quote Chris Jones from Met Office Hadley Centre "the key thing - to affect climate - is that it gets ash/dust up into the stratosphere. Otherwise it's not long-lived enough in the atmosphere. As I understand it this one was underwater, so probably unlikely to do so". Of course this is early days
  9. After the high pressure biefly reasserts itself on Monday it starts to slip south east Tues/Weds as another front tracks down the country
  10. I have been reading post after post that give the distinct impression that if you take 'chasing cold' out of the equation there is nowt interesting about meteorology/weather. Quite depressing and frankly very boring.
  11. Much cloudier day today, particularly over England and Wales, where the early low cloud/fog could well persist resulting in quite a chilly day. But tonight the cold front, mentioned in previous posts, is starting to move south over Scotland and through the night and tomorrow will continue it's travels accompanied by cloud and some patchy rain/drizzle as it slowly weakens. But behind the front much fresher air and more sunshine, albeit the odd shower in the NW. Note some rain/showers from a trough in the SW/S in the early hours tomorrow
  12. A weakening cold front tracking south down the country on Sunday, eventually becoming just a c;loud feature, as high pressure beats a tempory retreat. And as there ls not much to be said about the rest of the output that hasn't been said before, a quick glance at the second week of Feb. from the latest gfs ext/ec weeklies. But actually they indicate a not unfamiliar picture with the tpv lobe northern Canada; relatively strong westerly upper flow across the Atlantic to perhaps some influence from the Azores HP and temps around average. Now what's that quote I'm looking for. Ah yes "They think it's all over - it is now"
  13. Some dense fog around over England and Wales at the moment but if and once this clears through the morning another sunny day beckons. But more cloud over Scotland, particularly the north where it might hang around all day with some patchy drizzle. Frost and fog developing again tonight and tomorrow likely cloudier day than today
  14. Sorry RabbitEars, I should have included this in the original post. Hope it helps Tropopause fold is the extrusion of stratospheric air within an upper-tropospheric baroclinic zone which slopes downward from a normal tropopause level ( ~200--300 hPa) to the middle troposphere ( ~500--700 hPa). The tropopause fold is a mesoscale feature which forms in response to strong descent at the tropopause level. It constitutes an intense phase of upper tropospheric frontal development in which the tropopause undulation collapses. In regions of confluent flow the tropopause may be deformed such that it will form a fold (as shown in Fig. 1.9) which will decay after 1 or 2 days. During the build up phase of a fold the flow is generally conservative, whereas the decay phase is characterized through nonconservative flow, e.g., diabatic heating and turbulent mixing. It is these nonconservative processes which achieve the stratosphere-troposphere exchange. The most vigorous tropopause folds occur during the winter and spring and are less frequent than cyclone development. They are usually observed downstream from a ridge, where there is large-scale descent in the entrance region of an upperlevel jet streak. Ozone-rich air originates in the lower stratosphere, west of the trough axis on the cyclonic side of the upper-level jet streak. This airstream then descends anticyclonically to the lower troposphere east of the surface high-pressure system or crosses the trough axis and ascends. Two major types of tropopause folds are noted. One is associated with the polar front jet (PFJ), which may extend deep into the troposphere along the polar front. In some PFJ tropopause folds, significant intrusion of stratospheric air deep into the troposphere occurs. The other one is associated with the subtropical jet stream (STJ) and subtropical front, which is confined in the upper troposphere only and rarely extends downward below 500 hPa. The positions of the tropical tropopause and the polar tropopause along with the formation of subtropical jet stream over the rnidlatitude region are schematically shown in Fig. 1.10. Vertical intrusions of the dynamical tropopause into the troposphere, which are folded due to differential isentropic advection, are also known as tropopause folds. Source: Stratosphere Troposphere Interactions K Mohanahumar
  15. No significant changes with the NH profile this evening. Some slight differences with the structure/alignment of the tpv which impacts to some extent on the position of the surface high cell in relation to the UK and thus some variation vis the detail, Likely very dry and temps around average but perhaps a tad above over the northern half of the country
  16. And a quick preempt of this evening's gfs ext/ec weeklies outputs with a glance at this morning's extended. The salient ppoints: Aleutian low/Alaskan ridge > Siberia adjacent to the tpv lobe northern Canada > northern Russia; strong westerly upper flow exiting the eastern seaboard around the subtropical high, amplifying to some extent in mid Atlantic, to the east European trough. Likely pretty dry with temps around average
  17. After a cloudless morning a fair amount of Cu build up in the last hour quickly flattening out to Sc satellite image from METOP-C overhead at 2022/01/13 11:15 UTC
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