Storm Forecast
Valid: Fri 07 Jul 2006 06:00 to Sat 08 Jul 2006 06:00 UTC
Issued: Thu 06 Jul 2006 20:25
Forecaster: TUSCHY

SYNOPSIS

Strengthening trough, tilted in a more negatively direction, will continue its slow eastward movement... Broad area of geopotential height falls will accompany this development over most parts of central Europe and this should set the stage for widespread TSTM development.
Weak pressure differences prevail over most parts of eastern and northern Europe and this,combined with a humid and warm airmass, will be conducive for scattered TSTM development.
Most areas of the Mediterranean ( exluded the central part) will see hot and dry conditions.

DISCUSSION

...Italy and surrounding areas...

Marginal developed open wave/upper-level disturbance will cross Italy from NW towards the SE during the next 24 hours... A slight cool down in the mid-levels and a warm/humid boundary layer will support the models, which show moderately well developd mid-level lapse rates.... Instability release of ~ 1000 J/kg looks reasonable and this,combined with 10-15m/s DLS, will be enough for a few organized cells to develop ( even an isolated supercell in the level-1 area can't be ruled out )... Main threat will be a large hail and isolated severe wind gust risk.

....NE/E Germany and western Poland....

There should be an area of enhanced organized TSTM possibility in the highlighted region and therefore a level 1 was issued for E/NE Germany and western Poland.

Strong diabatic heating should take place during the day hours and scattered TSTM development can be expected.... Conditions will continue to improve for TSTM development, because of strengthening lift ( right entrance region of an upper-level streak)... This should support a broad area of a marginal pressure drop in the level-1 region and there are signals in the moisture advection charts, that a smaller-scale eddy could develop over eastern Germany, moving slowly towards the north during the evening / night hours.
DLS ( ~10m/s) will be rather weak, but a line of storms could form and attendant momentum should be enough for some kind of organization...I went with a far eastward extension of the level-1 area, because new cell growth towards the area with higher instability looks reasonable.
There will be an isolated large hail risk mainly with any afternoon/early evening storm and a possibly increasing lower-end severe wind gust threat later on.

The rest of central Europe will see an high instability - weak shear environment and main risk looks like to be a marginal hail threat and torrential rain ( isolated flash flooding possible).

Lower instability values, but DLS of 15m/s will be enough for a few organized storms over northern Europe with an attendant, sporadic severe wind gust risk.

...Extreme NE Algeria/NW Tunisia...

Conditions will again become favorable for a well defined sea breeze front, to move inland... Strengthening thermal circulation along the front and intense prefrontal heating ( up to 40°C ) should help a few storms to penetrate the cap.
Strong shear ( up to 20m/s ) and high SRH values will be fine for each developing storm to produce large hail and an isolated severe wind gust.
For now, a level-1 will not be issued , because of the difficult handling of see-breeze fronts ( exact position ) and a very constricted area of strong moisture convergence.