Storm Forecast
Valid: Wed 29 Dec 2010 06:00 to Thu 30 Dec 2010 06:00 UTC
Issued: Tue 28 Dec 2010 23:19
Forecaster: PUCIK

SYNOPSIS

As a complex synoptic setup evolves over Europe during the day, dominant features will be two cyclonic vortices. The first one will be placed to the west of Iberia, slowly amplifying towards east. The second one will stagnate over Eastern Europe, its center filled with arctic airmass characterised by temperatures below -10°C at 850 hPa level. Its frontal system will travel across Southern Russia northwards. Later into the forecast period, short-wave trough and attendant surface cyclone with frontal system will affect mostly Northwestern Scandinavia. A high pressure system at the surface mostly deliniates the regions which are under the artic airmass.

The only area of interest will be Southwestern Iberia. Warm temperatures over the ocean along with cooling mid-levels and modest synoptic-scale upward motion should contribute to the development of conditional instability. GFS predicts MLCAPE values in range approximately from 500-100 J/kg, ECMWF being the more pessimistic one with values generally below 500 J/kg. With strong southwesterly flow enhancing bulk wind shear values mostly displaced to the east of the instability area, mostly weakly organised convection is forecast. With strong southerly flow at 850 to 700 hPa advecting moisture northward along with several vorticity maxima crossing the region (the most prominent one during the night hours), several rounds of showers or thunderstorms are possible with possible cell training as they move northwards. Nevertheless, overal threat of excessive precipitation, albeit existing, should not meet the criteria for Level 1.