SYNOPSIS
A sharp and quite intense upper trough is present over western Europe, with a short-wave trough axis extending from west of the British Isles to central Algeria. To the east of this through, subtropical high over east central Mediterranean ridges into central Europe and North Sea. During the period, the southern part of the trough turns northward over west Mediterranean, while the geopotential over Central Europe slightly increases. At lower levels, a tongue of subtropical air spreads into Germany, and steep mid-level lapse rates indicated by latest ascends are expected from central Mediterranean to Balkans, and Germany. Models also indicate rich low-level moisture in the range of the warmest air from northern Balkans to Benelux, and diurnal heating will likely result in rather high CAPE. Low-level dry air mass remains in the range of surface high pressure from Scandinavia to Poland and Ukraine. Maritime air mass is present over western Europe.
Some uncertainties exist about initiation over most of the region, as quite strong capping inversion may be present. Latest models indicate that quite strong QG forcing will be present ahead of propagating jet streak from eastern France to Benelux. In the range of the frontal boundary, quite widespread convection is expected during the day spreading northwards over eastern France, western Germany, and Benelux. Given strong vertical wind shear, a MCS seems to be likely, and strong to severe wind gusts as well as intense precipitation are expected. More isolated convection at the eastern and southern flank of the MCS may also produce large hail and severe wind gusts. To the south, new convection will likely develop over western Alpine region spreading northward into south-western Germany. Convection may me embedded in a stratiform rain band initially and may be elevated over some places, but given strong DLS, a few mesocyclones are forecast to produce severe wind gusts and isolated severe hail. Further east, convective activity will be more isolated given quite large CIN and weaker forcing. Models indicate a convergence zone from central Germany to northern Austria and another north of the Alps over southern Germany. Along both convergence lines, low-level moisture flux convergence is expected to lead to high CAPE, but there are uncertainties about low-level moisture at this time. Current thinking is that some isolated storms will develop along the main convergence line from north-western Germany to western Czech Republic and maybe further south-east over Austria. Best potential for large hail is expected in the northern part of the convergence as DLS decreases to the south, but every isolated storm that form will have the potential of severe hail given high CAPE and at least moderate DLS. Local flash flooding is also not excluded. Tornadoes are not ruled out in the range of the convergence zone, although quite large CIN and relatively weak LLS will be limiting factors. Convective activity will spread north-eastwards during the night, while severe thread will likely decrease.
A sharp and quite intense upper trough is present over western Europe, with a short-wave trough axis extending from west of the British Isles to central Algeria. To the east of this through, subtropical high over east central Mediterranean ridges into central Europe and North Sea. During the period, the southern part of the trough turns northward over west Mediterranean, while the geopotential over Central Europe slightly increases. At lower levels, a tongue of subtropical air spreads into Germany, and steep mid-level lapse rates indicated by latest ascends are expected from central Mediterranean to Balkans, and Germany. Models also indicate rich low-level moisture in the range of the warmest air from northern Balkans to Benelux, and diurnal heating will likely result in rather high CAPE. Low-level dry air mass remains in the range of surface high pressure from Scandinavia to Poland and Ukraine. Maritime air mass is present over western Europe.
Some uncertainties exist about initiation over most of the region, as quite strong capping inversion may be present. Latest models indicate that quite strong QG forcing will be present ahead of propagating jet streak from eastern France to Benelux. In the range of the frontal boundary, quite widespread convection is expected during the day spreading northwards over eastern France, western Germany, and Benelux. Given strong vertical wind shear, a MCS seems to be likely, and strong to severe wind gusts as well as intense precipitation are expected. More isolated convection at the eastern and southern flank of the MCS may also produce large hail and severe wind gusts. To the south, new convection will likely develop over western Alpine region spreading northward into south-western Germany. Convection may me embedded in a stratiform rain band initially and may be elevated over some places, but given strong DLS, a few mesocyclones are forecast to produce severe wind gusts and isolated severe hail. Further east, convective activity will be more isolated given quite large CIN and weaker forcing. Models indicate a convergence zone from central Germany to northern Austria and another north of the Alps over southern Germany. Along both convergence lines, low-level moisture flux convergence is expected to lead to high CAPE, but there are uncertainties about low-level moisture at this time. Current thinking is that some isolated storms will develop along the main convergence line from north-western Germany to western Czech Republic and maybe further south-east over Austria. Best potential for large hail is expected in the northern part of the convergence as DLS decreases to the south, but every isolated storm that form will have the potential of severe hail given high CAPE and at least moderate DLS. Local flash flooding is also not excluded. Tornadoes are not ruled out in the range of the convergence zone, although quite large CIN and relatively weak LLS will be limiting factors. Convective activity will spread north-eastwards during the night, while severe thread will likely decrease.
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