CONVECTIVE FORECAST
VALID Sat 18 Jun 06:00 - Sun 19 Jun 06:00 2005 (UTC)
ISSUED: 17 Jun 17:01 (UTC)
FORECASTER: Dahl

There is a slight risk of severe thunderstorms forecast across NE Romania ... Moldova ... Ukraine.

SYNOPSIS

Vort max over S Sweden/the Baltic Sea on Friday evening ... will dig SEWD ... and reach the central Ukraine late in the period ... phasing with weakening central-Mediterranean upper cut-off low. Meanwhile ... upper ridge over W and central Europe will build northwards. At low levels ... SFC low will deepen over E Europe in association with the digging trough ... Atlantic SFC low expected to remain in place ... advecting increasingly warm/moist air across the British Isles. Between these cyclones ... weakening SFC high is covering central portions of Europe ... with quiescent conditions persisting across SRN Europe.

DISCUSSION

...NE Romania ... Moldova ... Ukraine...
Weakly unstable and virtually uncapped air mass is present over much of E Europe. Diurnally driven TSTMS should develop along orographic features again ... but should become focused along SEWD moving cold front trailing from the strengthening low. Strong forcing for UVM and minimal capping should favor numerous cells ... likely to coagulate into one or more larger MCSs. Moderately strong deep shear is likely to be in place ... supportive of short lines/bow echoes and mesocyclones imbedded in the convective systems ... with an attendant wind/hail threat. Weak capping and partly low LCL heights ... along with increasing low-level shear may also favor a few tornadoes. Though widespread convective development/cell interaction may to some extent limit organized severe threat ... SLGT seems to be marginally warranted. Some uncertainty exists of the eastward extent of the unstable air mass ... as plume of somewhat drier/stable air seems to be entrained into the prefrontal environment.

...Iberian Peninsula ... S France...
Isolated high-bayed TSTMS will likely form over Iberia in the late afternoon hours again. CAPE should be minimal ... but deeply mixed subcloud layer will likely promote strong outflow winds ... which may briefly attain severe levels. TSTM coverage is expected to be low ... and severe threat very local/brief ... so that a SLGT does not appear to be necessary ATTM. Convective activity may spread as far northwards as into S France.

...British Isles...
Much of the air spreading across the UK will have had a history of subsidence ... thus exhibiting fairly meager lapse rates. GFS and NMM are generating substantial CAPE towards midday over the Isles ... which seems to be rather unrealistic. Expect not much of a convective threat across the UK during Saturday until late evening.

It seems that a plume of Spanish EML will advect across the very W portions of the British Isles towards early Sunday morning ... However ... it seems that the EML will remain well S of DCVA-related UVV regime ... and confidence in TSTM development remains limited ATTM.

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