CONVECTIVE FORECAST
VALID Sun 19 Jun 06:00 - Mon 20 Jun 06:00 2005 (UTC)
ISSUED: 18 Jun 19:25 (UTC)
FORECASTER: Dahl

SYNOPSIS

Not too of a change expected ... E European/Russian upper low will remain in place trough Sunday ... as will be central European upper ridge and the Atlantic upper low. Peripheral vort maxima are progged to affect the NW parts of the British Isles and may be one focus for convective development. At low levels ... quiescent conditions persist across the SRN parts of Europe ... with two SFC lows present over W Russia and the east Atlantic ... and a weakening SFC high in between over central Europe.

DISCUSSION

...United Kingdom...
It seems that weak instability will form again across the UK ... conditional on degree of SFC heating occurring in the prefrontal environment. Weak large scale forcing for ascent and continued advection of steep mid-level lapse rates across the UK should also act to improve instability ... though capping may increase some.

Deep shear is expected to increase from about 5 m/s to 20 m/s from the SW UK towards the extreme north. Low-level shear should be rather weak with less than 10 m/s.

Main concern is that convection fails to initiate given that vort maxima are expected to remain well W of the SFC boundary ... so that large-scale ascent is expected to remain quite weak across the central UK. Mesoscale lift along and ahead of the front ... or orographic features may initiate isolated TSTMS in the afternoon/early evening hours, though.

Early Monday morning ... GFS advertises some stronger DCVA-related ascent ... which may aid in re-development of the TSTMS along the front ... though the bad timing may turn out to limit convective threat.

Those storms that form should have some potential to become severe ... main threats being marginally severe wind gusts and some hail. Marginal setup and uncertainty regarding the TSTM coverage preclude a SLGT ATTM.

...Iberian Peninsula...
Another round of mainly diurnally driven high-based TSTMS is expected over Iberia. Especially the WRN portions of the Peninsula may be affected by weak/ill-defined vort maxima ... and trend of increasing TSTM coverage during the last days is expected to continue. Storms should be capable of producing severe outflow winds given deep/dry CBLs. Given minimal shear and minimal CAPE ... degree of TSTM organization should be limited ... though storms may merge into one or more larger clusters in the evening hours.

...E Poland ... Belarus ... WRN Ukraine...
In the wake of the cold front associated with the E-European SFC low ... showers and TSTMS are expected to develop in rather strong and increasinly dry NWLY flow once insolation removes SFC-based stable layer. Expect gusty winds with the convection given strong low-level shear ... but CAPE should be minimal and confidence in organized severe is rather low.

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