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Fig8.1.9.7-12: EFI and SOT chart  VT 22-23 July 2012 (T+156-180) from ensemble DT 00UTC 15 July 2012, with associated Cumulative Distribution Function (CDF) and meteogram with M-climate for the marked position.  The uncertainty is clear on the meteograms.  The CDF shows some ensemble members indicating temperature values above M-climate maximum and some below M-climate minimum and thus the SOT will show values for both the warm and cold tails.  This is shown on the chart where the SOT lines (black) overlap.  The airmasses are clearly very different as there is a large positive EFI indicative of high temperatures over eastern Europe and a large negative EFI indicative of low temperatures over western Europe.


An example of high probability of an extreme event.  Rainfall in the desert.

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Fig8.1.9.17-13:  Extreme Forecast Index for total precipitation during the 10 day period 00UTC 10 Apr 2023 to 00UTC 20 Apr 2023.   The forecast cumulative distribution function (CDF) suggests that during the period there is less than 10% probability of below 35mm precipitation, 90% probability of below 80mm precipitation, and 10% probability of greater than 80mm.  The forecast CDF (red) is well above the M-climate CDF (black) and shift of tails values are quite high.  For a desert region, quite moderate precipitation values can be devastating.


An example of high probability of an unusual event.  Very calm sea in the Mediterranean.

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Fig8.1.9.17-14: An example of a forecast of exceptionally calm conditions in the Mediterranean.  The chart shows extreme forecast index (EFI) for wave height during the 24 hour period 00UTC 10 Apr 2023 to 00UTC 11 Apr 2023.  The colours on the cumulative frequency diagram show the results from the most recent ensemble runs; red is the latest.  The forecast cumulative distribution functions (CDF) of the last few runs suggest strongly that wave heights will be only just a few cm.  The forecast CDF (red) is well below the M-climate CDF (black) and EFI values are strongly negative. 


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