Storm Forecast
Valid: Mon 26 Jun 2006 06:00 to Tue 27 Jun 2006 06:00 UTC
Issued: Sun 25 Jun 2006 19:11
Forecaster: DAHL

SYNOPSIS

Quasi-stationary upper long-wave trough is present over W Europe ... providing deep and rather intense SWLY flow extending from western across central into northeastern portions of Europe. Rather weak but large upper low is expected to persist across the E Mediterranean. Vort max at the E periphery of the W European long-wave trough has induced cyclogenesis over Germany/Benelux ... which should spread northward across N Germany into the North Sea until late Monday night ... and strengthen in the late evening hours ahead of another vort max.

DISCUSSION

E Germany ... Poland

Sunday's 12Z ascents revealed predominantly shallow moisture throughout the warm sector ... though locally about 13 g/kg mean BL mixing ratios are realized as revealed by Sunday's LFSN 12 Z ascent. Potential problem on Monday may be extensive convective debris from overnight's convection ... that may limit insolation ... but on the other hand should increase LL moisture.
Indications are that MLCAPEs in the 1000 to 2000 J/kg range should be common across E-central Europe in the afternoon hours on Monday.

Deep shear should be on the order of 15 m/s ... but low-level flow should increase in response to the cyclogenesis ... and favorable shear profiles for severe evolution should exist across E Germany and Poland.

Main convergence should exist somewhat E of the main cold front ... and should be the primary focus for initiation. However ... multiple outflow boundaries and the cold front itself ... which should stretch across E Germany by Monday 12Z ... may also be a location where initiation occurs. Given rather weak capping owing to the absence of an EML ... rather widespread TSTMS are expected again. Primary mode should be linear/bowing storms capable of producing severe wind gusts ... though low-level wind profiles suggests that supercells are possible as well ... which will pose a threat for large hail ... damaging winds and a few tornadoes.

Convective scenario will strongly depend on the evolution and position of the SFC low ... which happens to be simulated rather incoherently. Large-scale forcing for ascent will be rather weak ... and shear somewhat marginal ... hence a level two is not introduced across Poland ATTM ... but an upgrade may be warranted later on.

S Balkans

Isolated TSTMS may form over the S Balkans ... and strong low-level flow and rather dry CBLs may support isolated severe outflow winds. Thinking is that coverage will be too low for a categorical threat level.