Finally an autumn period has adjusted across central Europe as large deep upper-level trough took place. Its somehow blocked between two large ridges, ones over Atlantic sea and another one over extreme Eastern Europe and Russia. This makes a perfect zonal flow pattern towards Alpine region and numerous disturbances are pushed into our regions. As it usually happens in such pattern, the main large trough occasionally pushes cold airmass towards the Alps and secondary lows (e.g. Genoa low) form. As interesting as it seems, we experienced one last night, another will be tomorrow’s night and a new Lee surface depression will likely come over weekend.
About 40-80mm rainfalls has been observed during the previous night, with some peaks exceeding 130mm especially along the N-ern Adriatic sea coast where strong near-surface surface convergence took place. (Cyclonic) Bora winds up to 50km/h were blowing across Friuli region while coastal areas experienced quite strong Scirocco (SSE) winds gusting up to 20m/s! This created a strong convergence and additionally intense rainfalls resulted in strong lifting mechanism. The minimum central pressure was near 990hPa when the center was just west of Istria in the morning hours. Strong cyclonic Bora then overspread the region (locally gusting up to 35m/s) and snowfalls has been observed in many places, locally reaching the lowlands especially in east-central Slovenia while W-ern Slovenia got snow on the ground down to about 450m ASL.
Anyway, a new strong cold front is rapidly approaching from W-ern Europe and can be perfectly seen on the current satellite and radar images. At about 20UTC it was located in NW France where a thick convective line formed along the main frontal boundary. This front is expected to cross the Alps the next night when Lee cyclone will form as well. Again, the pressure will be below 1000hPa, likely near 995hPa over Adriatic sea. Strong WAA will take place tomorrow by day and additional few tens of mm are likely due to strong ascent in the left-exit jet region with strong divergence in the upper levels overnight. Cold advection behind the low and front will rapidly cool the air and snow should arrive close to the lowlands again, but likely less intense than the last one.
However, here are few satellite, radar images and 18UTC surface analysis for pressure and front positions across Europe.
Image copyright: © EUMETSAT (2009)