11/13 - 11/16 Potential Storm Threat

[jm1220]

This case should serve as a valuable lesson about how important it is for the operational to share the support of the ensembles

as was the case with Sandy. There is no other piece of guidance that can beat the Euro ensembles for 5-10 day forecasts.

 

http://www.ecmwf.int/publications/newsletters/pdf/133.pdf

 

strike probability’ maps to identify risk – as on the upper right inset, which denotes forecasts from 12 UTC on the 21st (‘D­8.5’). Even this far in advance, before the HRES had shown anything noteworthy, the ENS was flagging up a region centred on New York as being at risk (~25% probabil­ ity), from a system yet to form!

Once a cyclone has formed one can use track and plume diagrams to follow its predicted evolution more precisely. Figure 2 includes two fore­ cast products specifically for Sandy: the main panel shows tracks in the ENS and the HRES, whilst the lower inset shows the central pressure evo­ lution along those forecast tracks (red dots are verifying data). These are all forecasts from 12 UTC on the 23rd (‘D­6.5’, which is 15 hours after Sandy was named). The products show the ENS providing strong support for the HRES, the vast majority of members showing landfall, along the coasts of the north­eastern USA or south­ eastern Canada, many at about the right time. Only a handful of members show a ‘right turn’ in the track, and miss land. Moreover most members show substantial deepening, and minimum pressure values, of the right order, at about the time of la

The evolution also made sense because of the pattern. Without the mega block being depicted across the model suite, Sandy would have been a typical weakening, transitioning hurricane ripping NE out to sea.

[Storm At Sea]

Historically, from the 90s to the mid-2000s, the Euro was remarkable for its accuracy from 96 hrs thru 144 hrs. I think the upgrades did it in much like the Nam. I prefer the Eta still to this day.