CONVECTIVE FORECAST
VALID 06Z SUN 11/07 - 05Z MON 12/07 2004
ISSUED: 11/07 00:01Z
FORECASTER: DAHL

There is a slight risk of severe thunderstorms forecast across E Romania ... Moldavia ... S-central Ukraine.

General thunderstorms are forecast across E-central and E Europe ... Scandinavia.

SYNOPSIS

Fairly stationary high-amplitude upper flow pattern is in place over Europe ... with extensive upper low covering E-central Europe and Scandinavia. Several perturbations continue to pivot around the periphery of this feature ... affecting mainly the N Mediterranean regions and SE Europe ... where weakly to moderately unstable air mass is present. SFC low pressure area is progged to persist across central Europe and Scandinavia ... centered over S Sweden.

DISCUSSION

...E Romania ... Moldavia ... S-central Ukraine...
Focus for potentially severe evolution remain the regions E and N of the Black Sea. However ... it looks that most unstable air will be moving across the Black Sea during the day ... and that E Romania and the S Ukraine won't see as much CAPE as on Saturday. GFS 18Z produces CAPEs on the order of 1500 J/kg over E Romania/S Ukraine though. Based on the limited model fields available ... it appears that 12Z and later model runs favor the slow removal of the unstable air mass ... and chances exist that it will be present over E Romania on Sunday. If the air mass recovers early enough during the day ... another round of widespread severe would be possible. However ... will await Sunday morning OBS and possibly the 12Z radiosonde data before issuing more emphatic outlook.

...N Adriatic Sea...
Models advertise weak CAPE over the N Adriatic which appears to be rather realistic based on modified Saturday 12Z ascents from N Italy. Storms will likely develop downstream from vort max crossing the central Mediterranean regions during the day. Deep shear should be on the order of 25+ m/s ... and a few rotating updrafts and short lines/bow echoes may occur ... posing a threat of severe wind gusts and large hail. Also ... a tornado or two could occur over the waters where LCL heights should be rather low. Current thinking is that TSTM coverage will be quite low ... and a SLGT is not necessary ATTM.

Farther S ... at the NRN edge of the EML ... chance for a few TSTMS appears to exist. However ... strength of thermodynamic profiles is quite uncertain ATTM ... and it is questionable whether TSTMS will initiate. Shear profiles would be supportive to severe evolution but confidence in TSTM development remains too low for TSTM outlook.

...central Europe ... UK...
Widespread shallow convection will likely develop with diurnal heating over large parts of central Europe and the UK in the polar air mass. This activity will likely produce occasional lightning ... but TSTM coverage should generally be quite low. Will place a TSTM area underneath the thermal-trough axis where convection should be deepest ... though weakly electrified convection may occur also outside this area.

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