Storm Forecast
Valid: Sun 03 Jul 2011 06:00 to Mon 04 Jul 2011 06:00 UTC
Issued: Sun 03 Jul 2011 07:01
Forecaster: SCHLENCZEK
A level 2 was issued for NE / E Iberia mainly for very large hail and damaging wind gusts.
A level 1 surrounding the level 2 was issued for E Iberia and the Balearic Islands mainly for large hail and severe wind gusts.
A level 1 was issued for N Algeria mainly for large hail and severe wind gusts.
A level 1 was issued for parts of Czech Republic, W Poland and E Germany mainly for excessive precipitation.
A level 1 was issued for S Norway, S Sweden and Denmark mainly for excessive precipitation.
A level 1 was issued for W Russia and parts of Estonia and Latvia mainly for large hail and severe wind gusts and to a lesser extent for tornadoes.
A level 1 was issued for the Bosporus region mainly for large hail and excessive precipitation.
SYNOPSIS
An occluding surface low over Poland moves slowly eastwards. Some showers and thunderstorms are expected along its cold front / occlusion and also in the warm sector over Russia.
Ahead of a shortwave trough over central Iberia, a developing surface low is found over NE Spain, moving to the northeast. Moderate to high instability is found over NE Spain with an overlap of strong 20 - 25 m/s deep layer shear which makes this region most favourable for severe weather on Sunday.
DISCUSSION
...E / NE Iberia...
Some 1000 J/kg MLCAPE are in place with strong deep layer shear and some 100 - 250 mē/sē SRH3. A deep EML, reaching from 850 hPa up to the 550 hPa level as seen in recent soundings from Barcelona and Murcia, provides some -100 to more than -200 J/kg CIN which should suppress widespread disorganised initiation. Current thinking is that an upper vort-max from the shortwave trough will trigger some isolated storms. Convection will tend to evolve into well-organised multicells and supercells, capable of producing large to very large hail and severe wind gusts due to evaporative cooling. Later in the period, discrete storms may merge into one or two MCSes with a pronounced severe wind gust threat. Continuous development of new storms further upstream may lead to excessive rainfall in some places but the hail / wind gust threat should be dominant. Although no high coverage of severe weather reports is expected, a level 2 was issued mainly for a few significant severe events as hail > 5 cm in diameter and wind gusts exceeding 33 m/s. Towards the east, CIN is strongly increasing and it is uncertain whether storms will develop over the Balearics or not. Isolated significant severe events are not ruled out when convection develops but the uncertainty w.r.t. initiation leads to a level 1.
For the same reasons as mentioned above, a level 1 is also issued for N Algeria.
...East-central Europe, S Scandinavia...
Continuous advection of warm and unstable air towards the Erz Mountains and other mountaneous areas within the discussed region may lead to a long-lasting period of intense convective and stratiform rainfall. Even though most of the storms are not very intense, a few flash flood events are expected.
Another region with a high potential of excessive rainfall is S Sweden and E Denmark where instability is a bit higher than in Germany and Czech Republic.
...W Russia and Baltics...
Near the cold front of the low pressure system over Poland, some 10 - 15 m/s deep layer shear overlap with approx. 1000 J/kg MLCAPE. A few isolated marginally severe hail events / isolated severe wind gusts could be expected with multicells and linear segments which are most likely to develop. Tornadoes are not very likely but an isolated event cannot be ruled out. A small low-end level 1 is introduced for the regions where isolated severe events may occur.
...Bosporus region...
Low-end instability and some 20 - 25 m/s of deep layer shear overlap over parts of Greece, Turkey and Bulgaria. SRH3 in order of 150 - 200 mē/sē may be sufficient for a few organised multicells and supercells which may produce isolated large hail and excessive precipitation due to high effective PWAT.
