Storm Forecast
Valid: Sun 29 Oct 2006 06:00 to Mon 30 Oct 2006 06:00 UTC
Issued: Sat 28 Oct 2006 18:07
Forecaster: DAHL

SYNOPSIS

Seasonably strong upper zonal flow is extending across central Europe ... with small/unstable perturbation N of the British Isles on Saturday evening progged to dig SEWD ... reaching the S Balkans late in the period. This feature is FCST to induce cyclogenesis over the Skagerrak/Kattegat region late Saturday evening. The resultant SFC low is expected to track eastward across Poland into the Ukraine during the period. W of this feature ... cold polar air will advect southward across the Balkans and the central Mediterranean regions. Much stronger cyclogenesis will take place over the Atlantic on Sunday ... affecting the NW European portions late in the period.

DISCUSSION

... Poland ...

GFS simulates weak CAPE over N Germany and Poland in the warm sector S of the developing low center. The only soundings available from this air mass ... which will undergo some vertical stretching however ... does not reveal much convective potential owing to stable lapse rates. Only chance that significant convective activity unfolds appears to be tied to upper-level dry slot. Development and position of such a feature should thus be monitored. If convection develops ... which is also supported by LME solutions ... presence of strong LLS and DLS will likely support severe evolution including tornadoes ... severe wind gusts and hail. Given strong signals in the models with respect to developing positive CAPE ... a level one is well warranted ATTM.

... S Portugal ... extreme SW Spain ...

Sufficient CAPE for convective activity is expected to exist over Portugal and extreme S Spain on Sunday ... also ... strong shear profiles should remain in place and some severe TSTM threat seems to exist. However ... forcing for UVVs is progged to be quite weak at the E periphery of weakening upper low ... and TSTM coverage should be quite low. Strong storm-relative LLS and DLS should support some threat for a tornado or two as well as for some hail with any cell that forms.

... Ionian Sea ...

GFS advertises weak CAPE over the Ionian Sea to develop on Sunday. However ... Saturday's soundings reveal a lack of LL moisture in this region ... and some doubt exists that substantial CAPE will develop until Sunday. Also ... there are only minimal signals in the QPFs ... and will thus refrain from a TSTM forecast for the Ionian Sea ATTM.