Storm Forecast
Valid: Fri 30 Jun 2006 06:00 to Sat 01 Jul 2006 06:00 UTC
Issued: Thu 29 Jun 2006 20:02
Forecaster: TUSCHY

SYNOPSIS

A weakening, but still active branch of SW-ly upper-level flow will continue to affect parts of Europe, although the whole streamline pattern will be very disturbed... South of a strengthening Scandinavian high pressure area, a smaller-scale disturbance will affect parts of central and SE-Europe...the main focus for TSTM activity this time.
The Mediterranean will stay dry and hot .
A well developed baroclinic zone , placed over eastern/northeastern Europe, will continue its eastward movement, but TSTMs should stay mostly sub-severe.
Strong insolation/diabtaic heating over the mountainous area of NE Spain / extreme SW France should produce a few storms ... forecast soundings show the chance for maturing storms to produce marginal hail or an isolated severe wind gust, but threat and coverage do not justify higher probabilities....
Parts of United Kingdom and Ireland will see marginal instability release and forcing along a SW-NE-ward placed frontal boundary and a few storms should develop with an isolated severe wind gust risk.

DISCUSSION

...Parts of CNTRL-SE Europe....

Conditions will become fine for a few organized storms to develop with a large to extremely large hail risk !

Despite the ingredients, pointing towards a few organized storms, there will be some small uncertainties, which finally could have affects on the exact TSTM development/ distribution.

During the first part of the forecast period,
the upper-level disturbance will be drawn into a more negatively tilted position, while attendant mid-/upper-level wind field starts to relax on the downstream side of this system... At the same time, strengthening baroclinic zone on its upstream side helps to re-intensify upper-level wind field again..with a final result that the trough axis looks like to shift back towards the west during the afternoon/evening hours...This should produce a more diffuse area of forcing on its downstream side,affecting the level areas.

A pool of pretty warm airmass will be advected from northern Italy towards the east, causing weakening lapse rates and instability release from the west ( over Croatia, Bosnia and Herzegovina and parts of Hungary ).

Finally...models like GFS indicate a SE-ward propagating convergence zone, but model pool has some problems in exact timing and placement of this zone ( warming of the midlevels ( talked about this one paragraph above) could restrict coverage of storms along this zone ).

All this favors the development of TSTMs at various places in an environment of localized better wind shear and forcing conditions, mainly in the level 1 and 2 areas.

Main concern will be in the level 2 area, where steep lapse rates, instability release of up to 1000 J/kg SBCAPE and DLS in the order of 15-20m/s should cause scattered TSTMs to develop with an attendant large hail and severe wind gust risk.

Extended the level-1 area far northward ( up to S-Poland ), because LL shear will be enhanced and don't want to exlude an isolated tornado development in this area.
A downgrade for this area could become necesarry later on, if it verifies, that this area of wrap-around moisture will be a stratified instead of a convective precipitation field.