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uk.sci.weather (UK Weather) (uk.sci.weather) For the discussion of daily weather events, chiefly affecting the UK and adjacent parts of Europe, both past and predicted. The discussion is open to all, but contributions on a practical scientific level are encouraged. |
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Weather Action published a rather dramatic forecast on the 16th
October. The full text can be read in a post by Steve Schulin on the 17th in this newsgroup entitled ... " Solar Weather Technique forecasts: massive storms to hit Britain and Europe (Oct 26-31, Nov 8-13 and Nov 24-28) ". I have monitored the day-to-day weather, particularly with respect to wind speeds, for the first 'phase' of this forecast, and the summary is below. Here is the Weather Action forecast relevant to that particular period:...... quote The three periods for which Weather Action are 90% confident there will be severe damaging storms: * October 26th to 31st or Nov 1st. Storm gusts of 80 to 100mph in places. This is likely to be a major storm period but probably only a 'warm-up' for what is to come in November. It is good there is now no election (eg on Nov 1st ) because the election period would have been severely disrupted (NB warning of the storms was passed on to the Labour leadership). The storm will track East and likely (80% confident) affect Holland, Denmark, South Norway, South Sweden and parts of North Germany. /quote And this is my view of the period:- .... Given the 'tone' of the forecast (above), which implied (from the general heading) a "severe damaging storm", then emergency planners and others tasked with forward planning for public safety would have felt let down - not only that, there would have been some considerable expense to provide the manpower & equipment necessary to cover such an event. Only one location recorded gusts in excess of 80 mph, and that was an uninhabited island off the far north of Scotland. All other wind reports were well within the 'normal envelope' of expectations for a late October, unsettled period. In particular, the mention of the 'possible' election being "severely disrupted" was grossly wide of the mark. There was nothing to suggest that the final week of such a campaign, or the election day itself would have been affected in any way. Two points to make:- (1): Anyone with any appropriate knowledge could have produced a forecast for this period on that date from *conventional* NWP output, e.g., GFS deterministic, GFES (ensemble), EC (ensemble & monthly anomaly forecasts) and MetO monthly anomaly forecasts. Solar techniques were not required, and indeed as the summary shows above, appear to lead to false conclusions. In particular, the GFS deterministic output 'flagged' the marked drive eastwards & southwards of a powerful jet 25/26 October very well at least 10 days in advance. (2): The 'disturbed' period is well within the change to potentially cyclonic / stormy conditions found by various workers for NW Europe (for example, Brooks & Lamb for the British Isles). http://www.booty.org.uk/booty.weathe...o/singular.htm Here is a day-by-day summary: 26th: This was the most 'active' day of this period, when a well-marked baroclinic zone, with associated surface cold front, crossed erratically from the WNW. The low-level flow was already strong to gale-force in the warm air ahead of the cold front north of about Galway Bay, and minor waves on the cold front enhanced the gradient as the front moved east. By far the strongest wind was recorded on the isolated island of North Rona (well away from the Scottish north coast), with a 'Storm 10' at both 00Z and 06Z. The highest gust I have available for this spot, and the highest *anywhere* in our immediate area of interest (limited data to me) is 74 knots (~85 mph) at 06Z. However, it is important to note that North Rona is NOT '10 m' representative; as a rough guide, the mean speeds should be reduced by a factor of 0.8. Elsewhere on this day, gales (defined either by mean speed or gusts, the latter as used in preparing a Shipping Forecast), affected exposed locations across the western & northern islands off Scotland, as well as coastal SW Norway. By 18Z, as far as I could tell, wind strengths were below gale-force over much of the area of NW maritime Europe south of 62N and between 20E and 10W, with the exception of the very exposed islands in North Utsire (sea area). 27th: By 06Z on this day, a rapidly moving wave depression was heading smartly ENE, crossing the Hebrides ~14Z/15Z, and ended up in the southern Norwegian Sea by 2359Z that day; another small 'hesitation' developed on the cold front during the evening. This was a 'classic' cold-frontal wave, beloved of text books, which markedly increased the gradient in the warm air over the British Isles and adjacent areas. No gales at first, but isolated gales observed by 06Z around SW Norway, and then more generally around northern and some western waters (of the British Isles) during the afternoon. From the limited data I have, the strongest gusts (excluding North Rona) were around 47 kn, for Lerwick & Belmullet at least. 28th: By 06Z, the cold front was now transitting Britain from the NW, introducing gale, or near-gale strengths to exposed SW coasts / islands of Britain as well as over coastal South & SW Norway; there was an isolated 'Severe Gale' using the gust criterion in the latter area, e.g. Bergen 18037G52. Also, the Shipping Forecaster's nightmare, a gale or near-gale (especially using the gust strength) through the Dover Strait and along exposed coasts of Belgium & the Netherlands. By midday, isolated gustiness would have 'verified' gales exposed headlands / islands central & eastern English Channel & the southern North Sea. Gales also around the exposed coasts & islands of Jutland, the far south of Norway and southern Sweden, though gusts were generally no worse than 52 kn, and for the most part 'windy' would have covered the story. By that evening, the gradient had eased sufficiently, and no gales were observed in our area. 29th: Classic cold-air (Polar Maritime) gustiness across northern waters (including coasts / islands of Northern Britain & SW Norway) - some close to gale (i.e. 43 kn), but generally just a decent blowy day. 30th: Although rain proved a problem to areas on the continent, no gales could be found this day. 31st: Strong westerly flow in the open warm sector affecting northern Britain & eventually Southern Norway. By 06Z, gales were setting in across sea areas off northern Scotland / around Northern Isles (but mainly because of the gust strength, e.g. Lerwick gusts = 43kn), extending to the exposed SW Norwegian coast / islands. (Once again North Rona stands out as anomalous: At 07Z, 240/43, gust 51kn, 08Z 240/42G50, 09Z 240/41G51. By midday, the situation had changed little, with gusts generally in these parts just into the 'gale' category, with Fair Isle (at 11Z) 230/34G48. Gales (by mean speeds or gusts) now more general along exposed Norwegian coasts north of roughly 61N. However, this was a short-lived blow (typical of autumn) and by early evening, gales were generally absent. 1st: No gales, though the low level flow was strong, slightly anticyclonically curved over northern Britain & northern Ireland, with and even stronger flow crossing southern Norway & south Sweden for a time. The wind eased through the afternoon fairly generally. General remarks: Apart from delay/cancellation to ferry traffic and possible cancellation of some inter-island flights during the windier periods, no 'significant' disruption was noted due to the wind. As regards the bit of the forecast relating to a 'General Election' in the UK, there was nothing in the weather type that would have had any adverse impact on campaign or voting, indeed it could be argued that over England and Wales, where the important seats would be fought for (for a Westminster parliament), then the weather was near ideal! My working notes can be seen at:- http://booty.org.uk/booty.weather/Ge...on_FxCheck.htm and much of the station data for these summaries has been taken from:- http://www.ogimet.com/index.phtml.en Martin. -- Martin Rowley E: W: booty.org.uk |
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