Storm Forecast
Valid: Wed 26 Jan 2011 06:00 to Thu 27 Jan 2011 06:00 UTC
Issued: Wed 26 Jan 2011 08:16
Forecaster: PUCIK

SYNOPSIS and DISCUSSION

The blocking situation is expected to persist with the main player being a large high at mid-levels of troposphere over the Atlantic, stretching to Western Scandinavia and during the day further to the east. At its forward flank, swift north-easterly flow is forecast, advecting colder airmass over most of Europe. A large trough is forecast over the remaining Europe. Three distinct short-waves are simulated - one undergoing a cut-off process over the Iberia, another one crossing Central Europe during the day and the last one crossing one in the northeasterly direction. The whole trough is filled with a cold airmass, especially the core of the Central European short-wave.

Closer towards the surface, situation is similar with zonally elongated high pressure system centered over the British Isles and progressively stretching to the east during the day. To the south, a shallow low will cover Southwestern Europe, centered just off the coasts of Southwest Portugal. This is also the only region where the airmass has a higher moisture content (observed dew points over 10°C) and along with an upward motion induced by a PVA at mid-levels can result in the marginal destabilisation. Both GFS and ECMWF agree on the CAPE being generally under 500 J/kg but as EL temperatures should stay well below -20°C, scattered thunderstorms can be observed. Heavy rainfall is simulated over the Northern Morocco and around the Strait of Gibraltar especially during the late evening and night hours, but convection is not expected to contribute significantly to it. Taking this into accout, as well as the marginal instability and weak wind shear, severe threat should be too low to warrant a Level 1.