Storm Forecast
Valid: Sun 24 Jul 2011 06:00 to Mon 25 Jul 2011 06:00 UTC
Issued: Sun 24 Jul 2011 05:37
Forecaster: SCHLENCZEK
A level 1 was issued for the W Mediterranean and E Spain mainly for large hail.
A level 1 was issued for N Algeria and NW Tunisia mainly for large hail and severe wind gusts.
A level 1 was issued for most parts of E / SE Europe mainly for large hail and severe wind gusts and to a lesser extent for excessive precipitation and tornadoes.
A level 1 was issued for S Finland and N-central Sweden for excessive precipitation.
A level 1 was issued for W Russia mainly for large hail.
SYNOPSIS
An upper cut-off low, centered over NE Germany, moves northwards during the forecast period. Several shortwave troughs are embedded in the upper level flow which surrounds the large cyclonic vortex, the strongest upper jet streak is found over the W / central Mediterranean and S Italy. Another shortwave trough is found over western Russia.
DISCUSSION
...W Mediterranean, Balearic Islands, N Algeria...
Some 1000 - 1500 J/kg CAPE are forecast by GFS and ECMWF for E Iberia and the W Mediterranean. Deep layer shear should be in order of 15 - 25 m/s which is supportive for well-organised multicells and supercells. Isolated large hail should be the most likely severe weather event for this area and a level 1 is issued. Later in the afternoon, the plume of unstable air moves southeastwards and affects N Algeria and NW Tunisia as well. A steeper vertical gradient of Theta-E should lead to some severe wind gusts there as well.
...Romania, Bulgaria, W Black Sea and Aegean Sea / Bosporus region...
Ahead of the upper low pressure system, hot and moist air is advected towards Romania. ECMWF predicts CAPE in order of 1000 - 2000 J/kg for some places in Romania and the W Black Sea / Aegean Sea. 0-6 km deep layer shear in order of 15 m/s is forecast and the development of well-organized storm systems with large hail and severe wind gusts can be expected. High CIN should preclude widespread initiation, but a few isolated storms could produce severe weather. Tornadoes are not completely ruled out but less likely than any other type of severe weather in the whole LVL1 region.
...E Poland and surrounding areas...
Some 500 - 1000 J/kg MLCAPE in place with 10 - 15 m/s of deep layer shear in the mountaneous regions of SE Poland may allow a few organised multicells with isolated large hail. Peak activity is expected around the early afternoon and storms will tend to weaken rapidly after sunset.
...Other parts of E / SE Europe...
All other parts of E / SE Europe which are included in the LVL1 region may get isolated large hail and excessive precipitation as main threat. The precip maximum predicted by GFS is centered around Croatia.
...Ionian Sea, C Mediterranean...
Some 1000 - 1500 J/kg CAPE and 15 - 20 m/s of 0-6 km deep layer shear overlap in a narrow band from Sicily and S Italy towards Crete. Even though CIN is rather high, the QG forcing from the upper trough could be sufficient to initiate some multicells or supercells which tend to merge into one or two MCSes. This scenario is quite conditional but a low-end LVL1 was issued for large hail and severe wind gusts.
...W Russia, Finland, N Norway and N-central Sweden...
Some hundred J/kg CAPE are forecast along the cold front of the low pressure system which stretches from N Ukraine via S Finland towards S Norway. 15 - 20 m/s of deep layer shear parallel to the front are in place which will increase the probability of storm systems with heavy precipitation as main threat, such as storm trains. Most of the precipitation is expected to fall in N Sweden. For this region, a marginal level 1 is issued.
The threat of heavy precipitation is somewhat reduced in W Russia. A few marginally severe hail events are possible and a marginal level 1 is also issued for this area.
