Storm Forecast
Valid: Mon 07 Aug 2006 06:00 to Tue 08 Aug 2006 06:00 UTC
Issued: Sun 06 Aug 2006 17:34
Forecaster: TUSCHY

SYNOPSIS

A broad and well developed upper-level trough is still placed over most parts of Europe.... While a strengthening trough-axis continues to lift out on its downstream side, another impulse on its upstream side supports a new upper-level trough development over W -Europe.
This configuration will affect most parts of Europe.
An approaching disturbance could locally support a few TSTMs over Norway and NW Sweden with an isolated severe wind gust risk, but currently expected coverage will be too low for warranting higher probabilities.

DISCUSSION

...W - coastal areas of the Black Sea, N-Bulgaria, Moldova and parts of the Ukraine...

Models like GFS indicate a well developed trough axis over Greece, shifting towards the NNE during the forecast period.... Adjacent increase in baroclinity supports the development of a strengthening jet core.
An aging frontal boundary is forecast to reach the areas of E-Romania , which has to be monitored ( concerning its exact position ) due to the containment of the region of TSTM evolution.
Current thinking is that the frontal boundary will be that far east, to suppress any significant moisture return ( which will be confined to the level -1 area ).... Main exception will be the Ukraine, where a few facts could support dewpoints in the range of 15-20°C.
This area will be placed in the developing and strengthening upper-level jet and its left exit region..... Models like GFS indicate a broad, but only weak pressure-fall area, which should support an increasing onshore flow.
This return flow will also be enhanced due to the approaching frontal boundary and we finally could see a retreating warm front ( strength of this onshore flow will confine the sector of higher dewpoints ).
A pool of moderatly steepend mid-level lapse rates, the approaching trough axis and the frontal boundary will be fine enough for scattered to widespread TSTM development in a nearly uncapped environment.
One or tow lines of storms are forecast to develop in 15-15m/s DLS...hence the severe wind gust threat will be augmented, but also don't want to exluce isolated large hail due to the all-over environment.

I went with a broad level-1 area over E-Romania due to the uncertain placement of the frontal boundary.

....N-France, the Low Countries and NW Germany...

A broad, but still not well defined, developing upper-level trough will cross the area of interest .... Cool mid-levels should enhance the lape rates and an area of 200-400 J/kg instability should develop... That much instability, combined with low LCLs and weak background shear will pose a funnel / short tornado / waterspout threat in the highlighted areas.... Indications are, that temperatures in the 700hPa level will drop 5-8°C in some locations ( compared to yesterday ), which should confine the region of an instability maximum to the lower levels ( also supportive for possible cold-air funnels ).