CONVECTIVE FORECAST
VALID Fri 12 Aug 06:00 - Sat 13 Aug 06:00 2005 (UTC)
ISSUED: 11 Aug 16:46 (UTC)
FORECASTER: TUSCHY

There is a slight risk of severe thunderstorms forecast across Parts of Serbia and Montenegro,Bulgaria and Romania

SYNOPSIS

Major upper-level low placed over Sweden and Norway and controls the weather pattern over most parts of Europe, where a split-flow regime was established during the past few days. Weak troughs and short waves, embedded in this flow regime will be the main convective players....During the night hours, a depression will reach Ireland and parts of Great Britain...Most areas around the Mediterranean area will see hot, dry and stable conditions.

DISCUSSION

...parts of Serbia and Montenegro,Bulgaria and Romania...
Well developed short wave, centered over the central Mediterranean area, will lift out northeastward, caused by downstream-dominant jet stream distribution and will fan out over the SLGT risk region...Despite the weakening forcing trend, conditions will be favorable for supercells to form in the risk area...Infiltrated cooler mid-level airmass and forecasted steep low level lapse rates should be conducive for about 500J/kg of instability. The northeastward propagating jet streak is forecasted to chop up into peaces, moving through the risk area...15-20m/s deep layer shear will be available, combined with low level shear of 5-10m/s and enhanced SRH values...Current thinking is that infiltrated dry airmass downstream of eastward propagating cold front should suppress widespread preliminary TSTM development, although each storm will pose a risk for large hail and damaging wind gusts ( forecasted inverted-V soundings ).
Eastward propagating cold front should pose a risk for isolated severe wind gusts and large hail during the night hours ...weakening background flow should be a reason for a decreasing severe weather risk trend during the night hours, but clustering of storms should pose a risk for locally heavy downpurs.

...Belgium,the Netherlands,Germany and the western Czech Republic...
Weakening short wave trough forecasted to shift eastward, accompanied by a cold front...Downstream of this system, a tongue of higher Theta-E values will be advected over most parts of Germany with an increase in humidity....Best kinematic values with up to about 20m/s of deep layer shear can be expected in the base of the short wave trough [ southern Germany ]...weak instability values forecasted in this area, so only isolated to scattered TSTM initiation expected... Main risk will be isolated severe wind gusts, but low LCLS and forecasted enhanced low level shear values ( 4km NMM )could also pose a marginal risk for an isolated tornado.
Further to the north, over parts of central Germany, Belgium and Netherlands, an environment, with forecasted steep low level lapse rates [Meiningen,Germany], enhanced low level CAPE values and about 10-15m/s deep layer shear should be conducive for an slightly enhanced chance for tornado development....otherwise, main risk will be marginal hail ( advection of cooler mid-level airmass ) and isolated severe wind gusts.
Under the base of the mid-level cold pool ( northern Germany),release of 200-500 J/kg of instability possible and isolated storms could develop with main risk being marginal hail.

...Estonia and the area east of the Gulf of Finland...
Deep layer shear of about 15m/s present southeast of major upper level trough, but low instability values forecasted...isolated storm development possible with main risk being strong to isolated severe wind gusts.

#