Storm Forecast
Valid: Wed 12 Nov 2008 06:00 to Thu 13 Nov 2008 06:00 UTC
Issued: Wed 12 Nov 2008 01:52
Forecaster: PUCIK

SYNOPSIS

A deep trough will slowly progress eastwards across Europe. Its southern part should split and a separate cut-off low will form by the end of forecast period. On the surface, insignificant cold front will influence the weather across Western and Middle Europe. Frontal trough, associated with the surface low, which is now decaying over N Scandinavia, will slowly fill. However, over the NW Mediterranean, surface low is predicted to form, providing favourable environment for thunderstorms. Otherwise, most of Europe should experience stable conditions, unfavourable for deep, moist convection.

DISCUSSION

No risk level is issued at the moment as no sufficient instability / wind shear overlap is expected to sustain organised convection. There are a few areas of interest, where thunderstorms should form and some of these will be discussed more thoroughly below.

...Northern sea/Denmark....

LLS values over 10 m/s with SREH 0-1 km locally over 160 J/kg are expected over Denmark in the morning and noon hours. However, unstable conditions are predicted over the sea, where cold mid-level temperatures overlaying warm SST lead to high lapse rates. Going inland, instability is predicted to rapidly decline. Therefore, thunderstorms are expected over the coastal areas, where the strongest convergence signals are shown by GFS model. As no obvious overlap of low level shear and instability is shown in several consequent model runs, LVL 1 for tornadoes is not warranted.


...Mediterranean Sea...

Cool mid level air mass will be advected over the warm sea surface, leading to conditional instability as a trough progresses eastwards. Moreover, surface low is predicted to form over the northern parts, so further convergence of low level wind field and destabilization will occur. Instability will however stay only marginal, MLCAPEs may climb above 500 J/kg, especially in the second half of forecast periods, on the forward side of surface low. Low level convergence and positive vorticity advection ahead of the trough suggest that thunderstorms will be easily initiated over the region. DLS should stay in order of 10 - 15 m/s, so storms should stay mostly in multicellular mode. With meager instability / shear, no severe weather is expected. Some sub-severe hail might occur, as well as one or two waterspouts, especially near the Italian coast, where the strongest convergence signals and significant LL instability release should overlap.