Storm Forecast
Valid: Thu 11 May 2006 06:00 to Fri 12 May 2006 06:00 UTC
Issued: Wed 10 May 2006 23:30
Forecaster: GATZEN/GROENEMEIJER
SYNOPSIS
A weak omega flow pattern is present over western Europe ... with a ridge from western Iberian Peninsula to southern Scandinavia and troughs over eastern Atlantic and eastern/southeastern Europe. During the period ... the eastern trough weakens and propagates eastward into Black Sea region ... while European ridge weakens and upper southwesterly flow expands to Iberian Peninsula and France/North Sea. At lower levels ... warm and relatively unstable airmass remains over British Isles, northern France, and northern Germany, where vertical wind shear will be weak. Warm airmass spreads into Iberian Peninsula and southern France. To the southeast ... relatively cool airmass is present over Balkans and northern Meditarrenean in the range and west of the upper trough.
DISCUSSION
...Iberian Peninsula...
A rather weak southwesterly upper flow is present over Iberian Peninsula during the forecast period ... and an embedded vort-maximum is expected to travel northeastwards during the day.
At lower levels, a warm airmass will present over the Iberian Peninsula. In the north, it is characterized by relatively rich low-level moisture. Some CAPE should form in response to diurnal heating, that creates a thermal low/convergent flow over centre of the country. Thunderstorms are are likely to form as a result.
A few organized convective cells are not ruled out ... in particular where easterly winds prevail, east of the thermal low. Such storms could be capable of producing large hail. The presence of a dry and well-mixed airmass, in particular over the southern half of the Iberian Peninsula, should create some chance for downbursts. In the north, a few slow-moving storms may lead to local flash flooding.
The overall threat appears to marginally warrant a level 1.
... Great Britain, Ireland...
Like England on Wednesday around 500-1000 J/kg of CAPE will probably form, this time over large parts of the British Isles. Some rather strong gusts and small hail are likely with the storms.
