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Satellite images from yr.no valid 9,12 and 18 UTC on the 28 October.
The figure above shows the maximum reported wind gusts (coloured numbers) for the 28 October and the MSLP for every 6th hour (contours).
This figure shows the same as the figure above but zoomed in over Denmark.
3. Mesoscale Structure of the Storm
Animation - IR |
Reading wind trace |
Reading temp/humidity trace |
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Animation - Reading WCB phase |
Animation - Reading SJ phase |
Animation - time of Reading max SJ gust |
Part of Sting Jet conceptual model |
Damage Swathe conceptual model |
The 8 panels above relate to the mesoscale structure of the storm as it passed over the UK (and beyond). We refer here to the warm conveyor belt (WCB), sting jet (SJ) and cold conveyor belt (CCB).
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A key point for ECMWF is whether or not the IFS can capture the strength of gusts observed, be it in the WCB or SJ phases (and indeed CCB, though that is not really looked at here).
The figure above shows the maximum reported wind gusts (coloured numbers) for the 28 October and the MSLP for every 6th hour (contours).
This figure shows the same as the figure above but zoomed in over Denmark.
Observations of wind speeds from University of Reading, valid for the 28 October.
The figures above show the maximum mean (10 minutes) wind speed (left) and wind gusts (right) for Denmark (from DMI). Here we see that the highest wind speeds occurred in the south.
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For hour by hour plots of MSLP and wind gusts from SMHI surface analysis (MESAN), see http://www.smhi.se/klimatdata/meteorologi/vind/storm-okt-2013 .
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4. Predictability (including 40r1 E-suite evaluation)
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4.1 HRES
The figures below shows forecasts of MSLP valid for 28 Oct 12 UTC and maximum wind gust during the 28 October. The o-suite is plotted in the left column and the e-suite in the right.
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The figure above shows forecasts initialised 25 Oct 0 UTC (+84h).
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4.2 ENS
The sequence of figures above shows the strike probability of cyclone with maximum wind speed (mean) over 60 kt (31 m/s) at 1 km height. The plots are valid for the 28 October (24-hours). The first forecast is from 28 Oct 0 UTC and one day is added for each plot. With longer lead time the feature is delayed (too slow) in the model, but the path of the cyclone seems very consistent up to 6 days before the landfall.
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CDF for wind gusts (left) and maximum mean wind speed (right) for Reading valid on the 28 October. Different colour represents different initial times and the o-suite (38r2, solid) and e-suite (40r1, dotted). Comparing different initial times, the forecast from 26 October (green and black), were the most severe. For the forecasts from the 27 October the wind speed was less. This is partly because the development of the cyclone occurred later and therefore had not reached such a deep stage when it passed over Reading. Comparing e-suite and o-suite, we see that the winds (both mean and gusts) are less in the e-suite and o-suite.
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4.3 Monthly forecasts
We cannot expect to see a strong signal for extreme cyclones in the monthly forecast. However, we can investigate whether the environment was favourable for windy conditions. The figures above show the weekly MSLP anomaly for the week starting on the 28 October. The first figure shows the forecast from the 28 October (Monday of the verifying week), followed by 24 Oct, 21 Oct, 17 Oct, 14 Oct and 10 Oct. At least for the 5 first forecasts a positive NAO signal (negative MSLP anomaly in the northern Atlantic and positive further south) is present. A positive NAO is usually leading to stronger winds over western Europe.
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4.4 Comparison with other centres
CDF for 10-metre mean wind for Reading (left) and a point (55N, 9E) in western Denmark(right). The data is of the maximum for 4 time step valid 28 Oct 0, 6,12 ,18 UTC and 29 Oct 0 UTC. The different colours represents different centres in the TIGGE archive. Two different initial times are plotted, 24 Oct 00 UTC (dotted) and 26 Oct 00 UTC (solid). For Reading the maximum mean wind was 10 m/s and the point in Denmark lies within the area of 25-30 m/s. The results for ECMWF is not convincing, especially for the Danish point; the ECMWF forecast has the lowest wind speeds for both initial times. However, there could be a mixture of land points and sea point between the difference centres. The figure below shows therefore the mean wind on 850 hPa for the same point. Here, at least for the 26 October, ECMWF shows the highest wind speeds. For the 24 October it could be the case that the timing error led to that the cyclone had not reached this point within the window for the diagnostics.
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5. Experience from general performance/other cases
- The sting jet of the 4 January storm over Scotland 2012. See attached poster from Tim Hewson.
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6. Good and bad aspects of the forecasts for the event
- The early signal of the storm in the forecasts (from ~6 days before the event).
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- The difference in wind speeds between e-suite and o-suite.
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7. Additional material