Storm Forecast
Valid: Sat 29 Jul 2006 06:00 to Sun 30 Jul 2006 06:00 UTC
Issued: Fri 28 Jul 2006 16:09
Forecaster: DAHL

SYNOPSIS

Weak northern branch of upper frontal zone is covering the northern and central portions of Europe ... with a weak trough slowly crossing S Scandinavia ... N Germany and Poland during the forecast period. Nearly as weak SRN branch of upper frontal zone will be covering the Mediterranean Sea ... with a weak trough ... phasing with the NRN-stream vort max ... crossing the central regions of the Mediterranean. Towards the end of the forecast period ... quite intense/large Atlantic upper low will plow into the westernmost parts of Europe ... with a well defined cold front trailing from the associated Atlantic SFC low across the E British Isles ... NW France into N Spain by Sunday 06Z. Otherwise ... except a few weak mesoscale SFC lows ... quiescent SFC conditions prevail.

DISCUSSION

Germany ... S Scandinavia

Despite the rich BL moisture across France and Germany on Friday ... the CAPE was rather modest owing to weak lapse rates per Friday's 12Z ascents. This will likely not change until Saturday ... and MLCAPEs are generally expected to be around or below 1000 J/kg. Deep-layer and low-level shear should remain quite weak as well ... and organized severe TSTM threat should be accordingly low. However ... given minimal capping ... TSTM coverage should again be quite high ... and one or two of the cells could become mesocyclonic upon favorably interacting with outflow boundaries or other mesoscale features ... and produce severe wind gusts and large hail. The majority of the storms however should be rather blobular ... the strongest of which may briefly produce gusty winds and hail ... but mostly below severe levels. Expect local flash flooding given quite moist BL and slow motion of the storms.

E-central Europe ... N Balkans

Towards the east over the Czech Republic ... Poland and the N Balkans ... low-level lapse rates should be somewhat stronger owing to weaker LL moisture ... resulting in higher LCL's. This suggests that the severe wind and hail threat should be somewhat enhanced compared to regions farther west ... but absence of vertical shear suggests that organized severe threat should be rather low. Nonetheless ... the strongest cells could produce hail/wind approaching severe limits.

Italy ... S France

Strongest thermodynamic fields should exist over Italy and possibly also over S France on Saturday ... with abundant BL moisture and rather steep low-/mid-level lapse rates ... which may locally boost the MLCAPEs into the 1500 to 2000 J/kg range. 10 to 15 m/s deep shear should be sufficient for some multicellular storms ... capable of producing large hail and severe wind gusts. The hail threat may locally be augmented by isolated mesocyclones.