dimanche 5 octobre 2014

European Storm Forecast Experiment

Storm Forecast
Storm Forecast
Valid: Sun 05 Oct 2014 06:00 to Mon 06 Oct 2014 06:00 UTC
Issued: Sat 04 Oct 2014 21:05
Forecaster: PUCIK
A level 1 was issued for SE / E Spain and the Balearic Sea mainly for the excessive precipitation and marginally large hail.

A level 1 was issued for E Tunisia, Sicily, S Italy and parts of the Ionian Sea mainly for excessive precipitation and large hail.

A level 2 was issued for SW Albania and W Greece mainly for excessive precipitation, large hail, tornadoes and severe wind gusts.


A large high pressure system centered on the border of Finnland and Russia causes cooler and dry airmass advection over much of eastern and central Europe. At the same time a cold front will affect France and W Germany during the day, slowly decaying as it detaches from the upper level forcing. Generally inconspicuous situation remains at the mid to upper troposphere, where lower geopotentials cover much of Europe. As sharp mid-tropospheric trough ejects towards Norway, France and the central Mediterranean will remain under broad trough.

Most of continetal Europe will be devoid of any DMC, perhaps apart from parts of France, Switzerland and a possibility of weakly electrified Cbs over N Hungary / S Slovakia. More interesting situation can be found to the south - over the Mediterranean Sea.


... SE / E Spain ...

In the prevailing mid to upper tropospheric NW-ly flow aloft, onshore flow from the sea will enhance DLS values, which may reach around 15 m/s, already sufficient for some well organised DMC. Some marginal to moderate CAPE will build-up as steeper lapse rates are advected from the interior of Spain. With cool mid-level temperatures, marginally large hail may occur with the stronger updrafts. In case of the cell training near the coastline, local excessive precipitation event may occur as well.

... E Tunisia, Sicily towards Ionian sea ...

With EML advecting over the moist boundary layer, moderate to high CAPE values are simulated by both GFS and ECMWF, reaching 2000 - 4000 J/kg over the sea, decreasing towards the north. No significant mid to upper tropospheric forcing is forecast, but low level convergence along the coastal areas will likely serve as the trigger for initiation. Regarding wind shear, 15 to 20 m/s of DLS is simulated over the western coastline of Greece and Albania, with smaller values elsewhere. Current thinking is that with southwesterly low level flow impinging on the coastline, several clusters may already be ongoing in the beggining of the forecast period. The highest threat will likely be during the overnight hours from Sunday to Monday over the Greece coastline. A large MCS is forecast to form, fed by very moist and highly unstable airmass. Due to the favourable setup, all kinds of severe will be possible, including large hail, severe wind gusts and tornadoes. The dominant one though should be excessive precipitation with high likelyhood of cell training as low level flow strengthens and thanks to the very moist airmass.

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