Extended Forecast
Valid: Fri 17 Jun 2016 06:00 to Sat 18 Jun 2016 06:00 UTC
Issued: Wed 15 Jun 2016 20:39
Forecaster: PUCIK

A level 2 was issued for NE Poland, NW Belarus and Baltic states mainly for damaging wind gusts, tornadoes and large hail and excessive precipitation.

A level 2 was issued for SE Poland, SW Belarus, W Ukraine, E Hungary, W Romania and N Serbia mainly for very large hail and severe wind gusts.

A level 1 surrounds a level 2 over parts of central Europe and Balkans mainly for large hail and severe wind gusts.


SYNOPSIS

The most important macro-synoptic feature will remain to be a highly amplified trough over W Europe with its base extending towards S Iberia. Embedded in a very strong S-ly to SW-ly mid to upper tropospheric flow, a short-wave trough will eject from Germany through Poland towards the Baltic states. Closer to the surface, deepening surface low will move from W Poland towards the Baltic Sea with its surface pressure falling below 990 hPa. Both GFS and ECMWF are quite consistent about the deepening and the approximate track of the low. At the same time, a plume of steep lapse rates will have advected from Sahara all the way to Ukraine. Low-level moisture will deepen ahead of the advancing cold-front and wrap around the advancing low.

Over the parts of central and E Europe, extensive overlap of CAPE and strong vertical wind shear points to another active day with potential for severe, well organised convection.

DISCUSSION

... NE Poland towards N Belarus and Baltic states ...

Strong forcing from the sharp short-wave trough and cold front will ensure widespread convective initiation over the area. Convection may be actually be ongoing already in the morning hours and will likely have a profound influence on the later development. Nevertheless, models agree on an overlap of moderate CAPE values (500 - 1500 J/kg) and strong vertical wind shear in the warm sector. As DLS reaches 20 - 30 m/s, convection will likely be very well-organised, either into broken line of supercells or a squall line with bowing segments. More isolated convection will be possible over the southern parts of the region and near the warm front. Enhanced low-level shear and curved hodographs (with around 300 m2/s2 of SRH0-3 km especially near the warm front) point to the risk of damaging wind gusts and/or tornadoes. Large, or even perhaps very large hail may occur with any more isolated supercell. Northwestern part of the area will also likely see an excessive rainfall threat.


... S Belarus to N Serbia ...

More isolated convection is forecast in this belt. Primary reasons are the lack of forcing from the short-wave and also high CIN values in the warm sector due to very high temperatures in the 850 to 700 hPa layer. Initiation will be most likely just along the cold front or over the mountain ranges, such as Carpathians. Any storm that develops will profit from moderate to high CAPE values (that may well exceed 2000 J/kg locally), steep lapse rates (7 - 8 K/km in the 800 - 600 hPa layer) and strong vertical wind shear (DLS 20 to 30 m/s). Very large hail will be likely from any supercell that develops. Severe wind gusts will be possible as well, especially if a cluster of cells develops into a bow-echo.