Storm Forecast
Valid: Wed 18 Jun 2008 06:00 to Thu 19 Jun 2008 06:00 UTC
Issued: Tue 17 Jun 2008 21:36
Forecaster: GATZEN

SYNOPSIS

A long-wave trough is present to the north-west of the European continent, yielding a south-westerly flow from
Bay of Biscay to southern Baltic Sea and north-western Russia. A short-wave trough embedded in the main flow is
expected to propagate north-eastward over Scandinavia and western Russia. Another trough is present from Poland
to Adriatic and will move eastward during the period. A weak surface pressure system is present in the wake of
both troughs from France to Poland und Ukraine.

In the range of the upper jet stream, a frontal boundary affects most of Europe. While the air is mostly stable
in the range of the weak high pressure, some instability is expected to develop from Adriatic Sea to the
Balkans, where weak low pressure is present. Over northern Europe, some instability will develop in the range of
cool polar air mass.

DISCUSSION

Central Adriatic to Balkans

Rather steep mid-level lapse rates are indicated by latest ascends over the Adriatic region that will likely
advect eastward into the Balkans with the main flow. Although low-level moisture is limited, CAPE is forecast to
develop. Rather warm mid-level air mass will also favour rather strong CIN initially. During the period, axis of
strong short-wave trough will enter the region. Given QG forcing and mid-level cooling, CIN will likely decrease
and convective initiation becomes likely especially over the mountains, where low-level lift may be strongest.
But numerous outflow-boundaries of overnights convection will also favour convection. Thunderstorms are forecast
to develop from Italy to Romania and Bulgaria during the period. Given strong south-westerly flow in mid-levels,
quite strong vertical wind shear exceeding 20 m/s in the lowest 3 km will result in rapidly developing
mesocyclones and bow echoes. Large or very large hail and severe wind gusts seem to be the main threat, although
tornadoes with more isolated supercells are not ruled out. Convection will likely merge into an MCS ahead of the
main vort-max moving into Romania during the night hours, while severe threat is expected to persist.

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