Storm Forecast
Valid: Wed 22 Oct 2008 06:00 to Thu 23 Oct 2008 06:00 UTC
Issued: Tue 21 Oct 2008 21:36
Forecaster: PUCIK

SYNOPSIS

The most prominent feature on 500 hPa maps will be a significant short-wave trough, which will progress NEwards during the forecast period. An interesting development will take place, as a cut off low will be separated from it . Its center should remain over SE parts of the Iberian coast. A belt of very strong mid level flow will have its delta on the rear side of the trough. On the contrary, Eastern Europe and most of the Mediterranean will be under the influence of ridge, which stretches from Italy to Russia. On the surface, strong pressure gradients will exist between Azorian high and a string of deep lows, which continue to affect NE Europe.
Another high will be centered over Ukraine/W Russia , guaranteeing stable conditions for most of Eastern Europe. Cold front will steadily move eastwards with its position by the end of forecast period from N Spain to W Russia.

DISCUSSION

Most of Europe should be under stable conditions, unfavourable for development of deep, moist convection. There will be few areas, however, where initiation of TSTMS is expected. Those will be discussed more thoroughly below. At the moment, we are not issuing any risk level, because conditions seem to be too hostile to support the possibility of severe weather occurence in storms.


....Northern Sea, Denmark, Baltic coast....

CAA regime will dominate the region with cool airmass overspreading the warm surface layer, influenced by higher SSTs. This should lead to high lapse rates at both low and mid levels ( Lapse rates btw 2 and 4 km should be over 7K/1000 m). Therefore, airmass should be conditionally unstable. MLCAPE values will be quite low - mostly between 200 and 400 J/kg. However, favourable synoptic setup and simulated ELs below -20°C suggest that lightning should occur with stronger cells. Significant low level buoyancy and convergence should be available, especially on the western coasts of Denmark and Norway. Therefore, few waterspout reports are possible. Weak deep level shear and only marginal instability preclude severe weather threat.

... W Mediterranean...

Shallow low pressure system has developed over the Balearic sea. A tongue of instability has spread in the region experiencing WAA. Highest MLCAPE values will be observed off the coast of Tunisia, possibly reaching 1500 J/kg. Widespread initiation is expected and TSTM development should gradually shift SE - wards with time, as cooler airmass will spread over the northern regions. DLS is predicted to stay in order of 10 - 15 m/s, so TSTMS should be organised into multicells. A belt of stronger flow will be observed on the western fringe of highlighted area ( enhanced flow around cold-core low), however weak instability will preclude any severe weather risk. Generally speaking, no sufficient overlap of instability, upper level support and shear will exist in the area, so no risk level is issued. One or two waterspouts might occur, as LL instability and surface convergence seem to be quite favourable for this type of weather.