Storm Forecast
Valid: Wed 21 Jun 2006 07:00 to Thu 22 Jun 2006 06:00 UTC
Issued: Wed 21 Jun 2006 06:42
Forecaster: GATZEN/GROENEMEIJER

+ + + MISSING TEXT ADDED 1001 UTC + + +

SYNOPSIS

Low geopotential is present over western Europe ... with a long-wave trough over France/Iberian Peninsula and intense polar trough moving into North Sea region. At the southern flank of the polar trough, Iberian low geopotential cuts off during the period, while remaining short-wave trough accelerates eastward ... affecting western Mediterranean, and central Europe. To the east ... upper ridge stretches from central Mediterranean to Poland and further to northern Russia, while relatively low geopotential covers Black Sea region. At lower levels ... a frontal boundary is present from Bay of Biscay to central France ... northeastern Germany ... Baltic states. While cool and stable airmass is expected northwest of this boundary ... airmass to the southeast is quite unstable.

DISCUSSION

Czech Republic, eastern Germany, Poland, southern Baltic Sea, Slovakia, Austria, Hungary

Rich boundary layer moisture is present over most of Germany, Poland, Czech Republic, and Austria ... where 0-1 avergae mixing ratios reach 12-14 g/kg. Aloft ... quite steep lapse rates are present as indicated by latest soundings over southern and central Germany. Today ... steep lapse rates should advect northeastward ahead of western European trough ... and given insolation during the morning hours ... MLCAPE50 on the order of 1000 J/kg, locally 1500 J/kg should be able to develop. Given quite weak CIN ... showers and thunderstorms will likely form during the day along old outflow boundaries. This may happen quite early in the day ... especially over eastern Germany. Thunderstorms should increase in coverage as weak vort-max and some WAA is expected in the southwesterly upper flow ... and QG forcing may lead to weak convergence/frontogenesis over central/eastern Germany. This development is uncertain, but weak capping suggests that scattered storms will initiate. As deep-layer shear is expected to be in the 15-20 m/s range, some supercells should be able to form. Main threats of these storms will be large, possibly very large, hail and damaging gusts. The focus of the development should shift eastward during the day into western Poland, the Czech Republic and Austria and into central Poland, Slovakia and possibly northern Hungary overnight. At that point, the severe threat should diminish as the convection becomes elevated.

southwestern, south-central Germany, Switzerland

Some storms may initiate over this area as well, although forcing should be rather weak. Nevertheless, given moderate shear and instability, a few isolated severe events appear possible, primarily large hail and possible some strong gusts.