Severe weather outlook – forecast across Europe. This forecast features areas of organized severe weather with risk levels and severe weather threats across the European continent.
SEVERE WEATHER OUTLOOK – DAY 1
Valid: 06/08/2020 06 UTC – 07/08/2020 06 UTC
Issued by: Severe Weather Europe
Forecaster: Marko Korošec
SUMMARY
Isolated to scattered severe storms with a threat for severe winds, large hail, and torrential rainfall are possible across the southern Balkan peninsula and northern Morocco on Thursday.
Overview of the risk areas across Europe
SYNOPTIC OVERVIEW
The upper-level ridge is strengthening across much of Europe while an upper low over the central Mediterranean finally weakens. A large trough remains over the North Atlantic, pushing a front into Ireland and the UK. A high-pressure system is expanding across much of the European continent.
FORECAST DISCUSSION
+++ Greece, Albania and North Macedonia +++
SLGT risk has been issued for north-central Greece, south-central Albania, and west-central North Macedonia with a threat for isolated severe storms, capable of producing severe winds, large hail, and torrential rainfall.
MRGL risk has been issued for areas surrounding the SLGT risk area including southern Italy, south Croatia, south Serbia into southwest Bulgaria with a limited threat for strong winds, marginal hail, and heavy rainfall.
A marginally unstable air mass remains across the Ionian Sea and southern Balkan peninsula, beneath a weakening upper low. The deep-layer shear is also in weakening trend and is mostly placed to the east of the instability maximum.
Therefore, some organized storms are possible to develop and could mainly bring severe winds, large hail, and torrential rainfall. Some storms are also likely across southern Italy, the south Adriatic Sea and the Ionian sea. With still quite cold mid-levels, waterspouts are likely to develop over the seas.
+++ north Morocco +++
SLGT risk has been issued for northern Morocco with a threat for severe storms, capable of producing severe winds, large hail, and torrential rainfall.
The environment will be conducive for organized storms, fueled by moderate instability and shear. A few supercells are possible.
+++ other areas +++
TSTM risk areas have been placed across the Alps, western Russia and Georgia where some storms are likely to occur but should remain sub-severe.
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Understanding Severe Weather Outlook
Severe Weather Outlook features areas of organized severe weather with risk levels and severe weather threats. Risk levels are divided into seven categories:
TSTM – Thunderstorms
MRGL – Marginal risk
SLGT – Slight risk
ENH – Enhanced risk
MDT – Moderate risk
HIGH – High risk
SIG – Significant risk
WNTR – Winter risk
Risk categories stand for the coverage and intensity of organized severe weather. Those could include supercells, squall lines, mesoscale convective systems, wind storms, flooding, snowstorms, or ice storms.
Severe weather threats include:
- large hail (of at least 2 cm in diameter)
- Tornadoes (including waterspouts)
- Wind gusts (convective or non-convective) above 25 m/s (or above 90 km/h)
- Torrential convective precipitation / Flash floods
- Excessive rainfall (100 mm within 12 hours) / snowfall (50 cm within 12 hours)
Extremely severe weather threats include:
- Large hail (of at least 5 cm in diameter)
- Tornadoes of F2 intensity or stronger
- Wind gusts (convective or non-convective) above 33 m/s (or above 119 km/h) or 12 Bft
- Torrential convective precipitation / Flash floods
- Excessive rainfall (150 mm within 12 hours or above ) / snowfall (above 100 cm within 24 hours)
Categories in the forecast represent the chance of severe weather occurring within a 40 km radius from a location. The used level is based on the conversion table of probabilistic risk into the outlook categories. A threat level is upgraded into a higher category if probabilities meet the threshold criteria for the specific threat (e.g. tornado, wind, hail, or rainfall threat).
Each individual threat area includes a detailed forecast map and discussion on the potential of severe weather threats.
Read more: Explanations for abbreviations (TSTM, SLGT, ENH, etc.)