Storm Forecast
Valid: Wed 06 Apr 2011 06:00 to Thu 07 Apr 2011 06:00 UTC
Issued: Tue 05 Apr 2011 21:58
Forecaster: PUCIK

No threat levels have been issued.

SYNOPSIS

The major macro-synoptic feature of the day at mid-levels of troposphere will be a large high, centered over France, amplifying towards west. To the north of the high, in the strong westerly flow, a short-wave trough is forecast to pass over the Norwegian Sea and affect Scandinavia in the night hours. To the east of high, a positively tilted trough will influence conditions over the Southeastern Mediterranean. Closer to the surface, a high will dominate over the Central Mediterranean, Central and Western Europe. Low pressure complex, on the other hand, will be concentrated in the Northern Europe.

Thanks to the large high, most of Europe will be under rather dry and stable conditions. There is no region which should experience widespread and/or severe thunderstorm activity during this forecast period, albeit few areas may experience some isolated thunderstorms during the day. These areas include Southwestern Turkey, Southern parts of the Ionian Sea, Northwestern Morroco and the western/northern part of Iberian penninsula, which will be discussed below.

DISCUSSION

... Western Iberia ...

In the prevailing south-easterly flow at mid and upper levels of troposphere, advection of elevated mixed-layer from Northern Africa is simulated by models, characterised by steep lapse rates. However, with easterly surface winds, rather dry conditions are forecast to prevail over the region and thanks to the very warm temperatures at 850 or 700 hPa, significant cap is forecast, as revaled by high CIN values (which were confirmed in Tuesday 12 UTC sounding from Southern Spain). Furthermore, no strong synoptic scale forcing is forecast either and despite the built-up of low to moderate degree of instability (WRF and ECMWF simulate well over 1000 J/kg of CAPE in the coastal areas of Northwestern Iberia), it is likely that no storms will manage to initialize with such strong cap. Along with the strenghtening southeasterly flow with height over the southwestern half of the region, a moderate wind-shear characterised by 15 m/s bulk shear in the 0-3 km layer is forecast, overlapping with instability. Especially this area will be monitored for signs of initiation, as well-organised convection with some severe threat could form in such conditions. As of now, however, initiation seems unlikely and no Level is introduced.