Status: Finalised Material from: Tim, Joaquin, Linus


 



1. Impact


2. Description of the event

The plots below show IR animation of the long-lived slow-moving convective cell developing (09-16Z) - arrow is Valencia and a visible image at 16Z showing overshooting tops, still. V is Valencia.


The plot below shows the precipitation from 27 November 06z to 28 November 06z.



3. Predictability

  

3.1 Data assimilation

 

3.2 HRES

The plots below show t850 and z500 for the analysis (left) and the forecast 3.5 days before.The synoptic pattern was cool, and cyclonic at upper levels, with relatively slack flow, all of which can favour substantial convective activity focussed over the ocean in autumn. With a 3-4 day lead time this pattern was fairly well predicted by HRES (though details not).

The plot below shows the vertical profile from the analysis 27 November 12z. The sounding is moist with high CAPE if one uses an SST of 18C for triggering. In fact it seems slightly odd that the CAPESHEAR EFI (see below), did not give a more prominent signal, given that there is quite a lot of vertical shear also on the sounding (~15m/s, surface to 500mb). Indeed the sounding suggests to me potential for very vigorous convection.



The plots below show 24-hour precipitation from observations (first plot) and HRES starting from the last forecast before the event.



3.3 ENS

The plots below show EFI and SOT for CAPE(first figure) and CAPE/SHEAR (2nd figure) for the period 0-24 h and the 3rd figure for CAPE and range (48-72h).



The plot below shows CDFs for precipitation forecasts for 27 November.



3.4 Monthly forecasts


3.5 Comparison with other centres


4. Experience from general performance/other cases


5. Good and bad aspects of the forecasts for the event


6. Additional material