Storm Forecast
Valid: Sun 21 May 2006 06:00 to Mon 22 May 2006 06:00 UTC
Issued: Sat 20 May 2006 21:34
Forecaster: DAHL

SYNOPSIS

Intense broad upper WLY flow is progged to back significantly over W Europe as Atlantic trough digs eastwards ... with downstream vort max ... which has affected Germany on Saturday ... quickly moving across NE Europe into NW Russia. Several weak/ill-defined vort maxima imbedded in the SRN regions of the upper frontal zone will affect the SRN portions of Europe. Strong SFC low accompanying the digging Atlantic trough ... will promote advection of warm/moist air across the WRN parts of Europe. Quiescent SFC conditions persist across SRN Europe.

DISCUSSION

... southern UK ... central France ... western Benelux ...

Like for Saturday ... models advertise CAPE to develop in the postfrontal environment over the SRN UK only ... with abundant SRH just E of the cold-frontal boundary. Allover scenario does not seem to be too dissimilar from that over central Europe on Saturday ... and indications are that shallow/narrow bands of convection may be possible along the front in high-SRH environment. Thinking is that linear nature of the storms will primarily account for severe straight-line wind threat ... though any isolated storm will have the potential for becoming supercellular ... posing an additional threat for marginally severe hail as well as for tornadoes.

Later in the day ... additional storms may develop along the cold front over N France ... Benelux and W Germany ... which may also become severe given quite favorable shear profiles. Severe threat should gradually diminish with loss of daytime heating ... though kinematic setup remains benign for isolated severe TSTMS through the late evening hours. TSTMS may spread as far eastwards as into central Germany late Sunday night/early Monday morning.

... Belarus ... extreme western Russia ...

TSTMS should redevelop ahead of vigorous vort max moving across NE Europe on Sunday. Shear profiles don't seem to be quite as strong as on Saturday ... but some severe potential should persist ... main threat being severe straight-line winds though a brief tornado or two cannot be ruled out with any isolated cell.

... Ukraine ... Moldova ... Romania ... Bulgaria ...

MLCAPE on the order of 1000 J/kg should persist across SE Europe ... and coupled with diurnal heating and several vort maxima crossing the region during the day ... a couple of TSTMS should develop during the day. Low-level and deep-layer shear seem to be somewhat marginal ... and main convective mode should again be multicells with a threat of strong outflow winds and some hail ... which may briefly approach severe limits. However ... interaction of cells with outflow boundaries of previous convection ... or other local effects ... may promote a few mesocyclones which may augment the large-hail threat. Allover severe threat appears to be too weakly organized for a categorical outlook ATTM.