Storm Forecast
Valid: Mon 15 Aug 2011 06:00 to Tue 16 Aug 2011 06:00 UTC
Issued: Sun 14 Aug 2011 21:48
Forecaster: KOROSEC
A level 1 was issued for E-CNTRL Alpine region into W Hungary, E Czech Republic, W Slovakia and E-CNTRL Poland mainly for strong to severe wind gusts, large hail and excessive convective rainfall.
A level 1 was issued for N Ukraine, E Belarus, eastern Baltic states and W Russia mainly for excessive convective rainfall, large hail and strong winds locally.
SYNOPSIS
A large upper trough is centered over extreme NW Europe. A few short-wave troughs rotate around this main trough, one crossing CNTRL Europe and Alpine region. Another short-wave moves northwards across southern Scandinavia. A weak upper low still on going over eastern Europe. Towards the Tuesday morning, a short-wave trough/frontal system approaches UK from the eastern Atlantic sea. At surface, a weakening SFC cold front extending from southern Scandinavia crossing central Europe during the forecast period.
An upper ridging with developing SFC high pressure is slowly spreading into SW Europe.
DISCUSSION
... E-CNTRL Alpine region into W Hungary, E Czech Republic, W Slovakia and E-CNTRL Poland ...
An eastward progressing trough/SFC front will be the focus for today's convective activity across the Alpine region and towards Poland. Airmass ahead of the front becomes moderately unstable with MLCAPEs approaching 1000 J/kg while rather marginal shear will be in place. GFS simulates a broad area of 10-15 m/s of deep layer shear across the level 1 area. Storms are expected to form mainly along the front and gain organization while progressing eastwards. Some severe storms are expected, capable of producing mainly large hail and strong to severe wind gusts. It is becoming likely that an MCS will form over NE Alps and moving across Czech Republic/Slovakia later on. Rather slow moving storm cells might bring excessive rainfall threat as well.
Areas further SW across the eastern Alpine region could expect a few pre-frontal storms with multicellular or even supercellular characteristics. But the main activity will again be aligned to the SFC front. A formation of the squall-line with embedded severe cells seems possible, racing ESE-wards from E Austria into western Hungary during the late afternoon/early evening hours. There, some strong to near severe wind gusts could be possible.
... N Ukraine, E Belarus, eastern Baltic states and W Russia ...
A weak upper cold-core low still affecting eastern Europe, but slowly diminishing on Monday. BL moisture is quite high across the region also further north towards the Baltic states, resulting in moderately high instability. As there is rather limited wind field/shear, organized severe convection is unlikely. However, slightly better shear seem to be found across the northern half of the level 1 area. Overall, mainly large hail, strong winds and excessive convective rainfall threat exists given the high CAPE and slow storm motion vectors.
... southern Scandinavia ...
A short-wave trough moves across this area today. Some convective activity is expected, but with quite limited instability and moderate shear in place. Some uncertainities for severe storms exist and a threat level is not warranted attm. However, area will be closely monitored for a possible upgrade into level 1 if conditions improve. Therefore, some threat for strong wind, brief funnel/tornado could not be ruled out.
