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The IR sequence shows, perhaps unsurprisingly, all the hallmarks of an extreme extra-tropical cyclone, including evidence of a SJ event. Notably, fingers of cold top cloud continue to emerge forwards from the tip of the cloud head, but evaporate as they descend (the 'smoking gun' effect). This happens first across S England, then on across the N Sea, and finally over S Denmark; thereafter there is more evidence of cold top cloud surrounding the cyclone, as the cold conveyor phase of the maturing cyclone takes over. The cyclone seems to fit the model proposed by Keith Browning in his October 1987 sting jet (QJRMS) paper very well, and also the model of related 'damage swathes' shown on the final panel. As well as the evaporating cloud fingers note the evidence on IR of curved slabs of slantwise upward motion extending NW from the low centre, with dry gap(s) inbetween. A new 'slab' develops at the start of the IR sequence, and relates also to a propogating band of intense rain at the surface - note the narrow band of bright echoes in the northern portion of all the radar sequences. In the SJ conceptual model this equates to one of the dark-shaded arrows on the top panel. The lighter shaded arrows, meanwhile, denoting evaporating descending branches, correspond to the dry gaps on the radar sting jet sequence, two of which are highlighted on the 'Reading max SJ gust' panel. It is expected from modelling studies performed by Pete Clark, that these descending branches will be the source of the main SJ gusts at the surface, and so it proves for this case, at least at the Reading university site, as the traces and radar show. Detailed analysis of the storm of October 30th 2000 has shown a similar correspondance. The temperature trace for Reading shows falling temperatures during the SJ phase, related perhaps to the mini cold fronts shown in the SJ conceptual model, though, perhaps significantly (?), there is a mini plateau at the time of maximum gust, which could conceivably relate to warming during a relatively dry stage of descent. Note also that the SJ conceptual model diagram corresponds to a more mature sting jet; at Reading we are just looking at the very beginning, wherein the tips of the lighter grey arrows (and mini cold fronts) would be much further back relative to the low centre position.
The maximum Reading gust for this case came in the warm sector, in WCB flow. It would appear from radar sequence that this may have been convectively enhanced. The sudden nature of the gust and the corresponding lack of increase in mean winds suggests that this was perhaps a finely balanced situation, where stability was, for the most part, just inhibiting the downward propogation of momentum needed for strong gusts.
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