Storm Forecast
Valid: Sun 23 Jul 2006 09:00 to Mon 24 Jul 2006 06:00 UTC
Issued: Sun 23 Jul 2006 08:46
Forecaster: DAHL

SYNOPSIS

Meandering westerly upper flow is extending across northern Europe and the northern parts of central Europe ahead of broad upper trough over the Atlantic ... which is making slow eastward progress ... thereby somewhat backing the upper flow over western Europe. Qiescent conditons prevailing at the surface except the weakening low N of the British Isels and a weak heat low to develop late this afternoon over the Iberian Peninsula.

DISCUSSION

Cnetral Europe

Mesoscale setup across central Europe is somewhat complicated by the presence of several weak mesoscale lows ... and by outflow boundaries/convective debris from Saturday's convection. One such mesolow ... which apparently is in a process of slight strengthening ... should linger over NE Germany ... and may favorably augment the low-level wind fields there ... especially in terms of low-level veering ... which even seems to be supported by the latest GFS run. Given poor handling by the models of the shear profiles in the past days ... thinking is that models may underestimate shear magnitudes as well today.

CAPE should not be extraordinarily high ... with common values in the 500 to 1000 J/kg range ... but indications are that a few multicellular storms and weak/short-lived mesocyclones may develop ... capable of producing large hail and damaging wind gusts. Tornadoes apparently have occurred during the past days ... but except weak capping ... the soundings still do not reveal an enhanced tornado threat.

Though slightly enhanced severe TSTM threat appears to exist across most of central Europe ... will introduce only one level-one threat ahead of the N-German mesolow where SFC winds should be backed most strongly.

Northern Spain

An isolated severe wind gust/large-hail event or two could occur with high-based convection that may develop over N Spain late in the day given increasing SRH and dry/deep sub-cloud layers. Coverage should be too low for a categorical threat however.

Italy

MLCAPEs in the 1500 to 2000 J/kg range should develop over Italy again ... and despite shear being negligible ... storms may briefly produce severe wind gusts and marginally severe hail. However ... indications are that TSTM coverage will be very low ... and a level-one threat does not seem to be warranted ATTM.