Storm Forecast
Valid: Sun 28 May 2006 06:00 to Mon 29 May 2006 06:00 UTC
Issued: Sat 27 May 2006 21:58
Forecaster: DAHL

SYNOPSIS

Strong upper westerly flow ... exhibiting several imbedded vort maxima ... persists across Europe. Associated low-level frontal zone ... stretching from N France across central Germany into E central Europe at the beginning of the period ... is expected to make some southward progress in response to amplifification of the upper disturbances. SFC-low complex should exist over NE portions of Europe ... providing N-central Europe with cool polar air mass. S of the frontal zone ... weakly unstable subtropical air is present.

DISCUSSION

Poland

Models advertise weak CAPE across Poland ... and later in the day across Belarus/extreme W Ukraine ahead/underneath of strong vort max. Current thinking is that the CAPE is associated with well and deeply mixed polar air ... though chances seem to exist that TSTMS will also form within weak warm sector ahead of the upper trough. Kinematic fields will be quite favorable for severe evolution ahead of the front where strong SRH is expected. In its wake ... shear should still be sufficient for strong wind gusts and some hail that may locally attain severe levels despite weaker low-level kinematic fields.

Initiation along/ahead of the front is quite uncertain ATTM ... but recent cases suggest that models tend to underestimate the convective development along weak baroclinic zones ahead of vigorous vort maxima. If convection forms indeed ... threat for rather widespread strong/severe wind gusts ... and a couple of tornadoes seems to exist. Despite the uncertainty ... a level ine seems to be warranted.

NE Italy ... N Balkans

Weakly unstable air mass is revealed by 12Z ascents across the N Balkans ... and scattered TSTMS should fromt along and S of the SFC front over NE Italy and the N Balkans. Deep shear should rapidly decrease towards the south ... but especially those TSTMS near the frontal boundary should become organized ... with a threat for large hail and severe wind gusts. LL shear is expected to be minimal ... and tornado threat does not appear to be particularly enhanced.

Iberian Peninsula

Saharan EML is currently overspreading the SRN Iberian Peninsula ... which should result in weakly unstable and capped inverted-V profiles. A few isolated TSTMS may develop in the late afternoon hours ... and could produce very strong/severe outflow winds. Weak shear and weak forcing for UVVs should limit allover extent of severe threat ... and a categorical risk is not necessary ATTM.