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: 02/08/2020 06 UTC – 03/08/2020 06 UTC
Issued by: Severe Weather Europe
Forecaster: Marko Korošec
 

SUMMARY

 
Organized severe storms with threat for severe winds, tornadoes, large hail and torrential rainfall are possible across the Alpine region and central Europe. Additional storms are possible across eastern Turkey and Georgia.
 

Overview of the risk areas across Europe

 

weather forecast

Explanations for abbreviations (TSTM, SLGT, ENH, etc.)

SYNOPTIC OVERVIEW

 
The North Atlantic depression moves towards western Europe, causing the upper-level ridge across central Europe to colapse. A large upper low rotates over northwestern Russia. At the surface, a frontal system moves towards the Alps with a pronounced frontal boundary moving east.

FORECAST DISCUSSION

 

+++ Switzerland, Germany, Czechia, Poland, Austria, Italy and Slovenia +++

 

weather forecast

 

MDT risk has been issued for the Alpine region, including Switzerland, extreme south Germany, western Austria and northern Italy with threat for severe storms, capable of producing severe winds, tornadoes, large hail and torrential/excessive rainfall with flash floods.

ENH/SLGT risks have been issued for areas surrounding the MDT risk area including south and east Germany, west-central Czechia into west Poland and north Austria. A threat for severe winds, large hail, and torrential rainfall will develop.

A rather widespread organized storms are expected to develop along the moving front from the western Alps and further north over central Germany. Conditions are likely to support quite a rapid evolution of the storms by mid-afternoon.

A moderately to locally strongly unstable and the sheared environment is present in the forecast MDT/ENH risk areas, especially over northern Italy. Conditions will be conducive for rotating storms to develop as well. A few intense supercells with large hail and severe winds are possible. Easterly low-level flow across the Po valley plains should enhance helicity and tornado threat as well. Flash floods are locally quite likely given the complex topography and huge amounts of rainfall forecasted.

Storms will likely merge into MCS in the evening hours while traveling towards east-northeast across the Alps, Austria, and southeast Germany towards Czechia. Severe winds and torrential rainfall will remain the primary threat. Activity will continue overnight.

+++ east Turkey, Georgia into southwest Russia +++

 

outlook
 

SLGT risk has been issued for eastern Turkey into Georgia and southwest Russia with threat for isolated to scaterred severe storms, capable of producing severe winds, large hail and torrential rainfall.

A moderate deep-layer shear with relatively low instability limits strongly organized storms. But a few supercells will be possible.

MRGL risk has been issued around the SLGT risk area, covering southwest Russia, eastern Black Sea and east-central Turkey. Here, a marginal threat for isolated severe storms with severe winds, large hail, and torrential rainfall is present.

+++ other areas +++

 

TSTM risk areas have been placed across the southern Norway, central Sweden, south Finland, extreme south Balkan and Atlas mountains in Morocco where convective 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 – Thundestorms
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 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.)