Storm Forecast
Valid: Thu 22 May 2008 06:00 to Fri 23 May 2008 06:00 UTC
Issued: Wed 21 May 2008 21:27
Forecaster: GATZEN

SYNOPSIS

European trough expands westward into eastern Atlantic during the period. To the east, main axis of the upper trough continues to turn north-eastward over Balkans. It is expected to reach Romania late in the period. Ahead of the trough axis, a strong upper jet streak enters Ukraine in the evening/night hours, leading to QG forcing.

DISCUSSION

Eastern Romania, western Ukraine, southern Belarus, parts of western Russia

Another period with widespread convection is forecast over this region, where quite strong instability will likely develop given steep mid-level lapse rates and rather rich low-level moisture. Latest models indicate CAPE in the range of 1000 J/kg during the day. Additionally, QG forcing is expected in the range of approaching jet streak and associated trough axis. Numerous outflow-boundaries from overnights convection as well as a broad frontal boundary will also lead to forcing to break the cap during the day. Thunderstorms that form may organize into multicells given quite strong vertical speed shear. Weak veering profiles may be present in the range of the frontal boundary and associated low-pressure-centers, and splitting storms may also be possible initially. Best potential for supercells exist near the northern edge of the warm air mass from northern Ukraine to Belarus and western Russia, where easterly surface winds are expected. A level 2 may be warranted over southern Belarus region, where best vertical wind shear and forcing due to a coupled jet will overlap with instability. Given quite rich low-level moisture and locally strong low-level buoyancy, supercells may be capable of producing tornadoes near the warm front, while most significant threat my turn to hail and wind gusts further south. Convection is expected to merge into another MCS during the afternoon and evening hours over Belarus, while severe threat is expected to weaken due to low-level stabilization.

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