Risk & Forecast Explanation

CESTOF forecasts show where thunderstorms and severe-weather hazards are possible in Central Europe. The risk category combines expected coverage, intensity, organization, and forecast confidence.

A higher risk does not mean every location inside the polygon will be hit. It means the environment is more supportive of severe storms and the chance of impactful weather is higher.

Back to forecast map

Quick reading guide

Color: main overall thunderstorm/severe-weather risk.

Hatching: highlighted area where a more significant hazard is possible.

Hazard maps: separate tornado, hail, and severe-wind probabilities.

Discussion: explains the reasoning behind the polygons.

Main CESTOF risk levels

The main risk polygon is the general forecast category. It is based on the expected storm coverage, storm intensity, possible hazards, and confidence.

TSTM

Thunderstorms possible

TSTM means that thunderstorms are possible, but severe weather is not currently expected to be widespread or organized.

Brief heavy rain, small hail, gusty winds, or occasional lightning may occur.
Severe weather is unlikely, but a very isolated stronger storm cannot be fully ruled out.

GNRL

Low-end severe chance

GNRL means that thunderstorms are expected or likely, with a low-end chance of isolated severe weather.

Storms may be scattered and locally stronger.
Severe hazards should remain isolated and mostly short-lived.
A few storms may produce small to marginally large hail, strong wind gusts, heavy rainfall, or frequent lightning.

SLGT

Isolated to scattered severe storms

SLGT means that isolated to scattered severe thunderstorms are possible.

A few storms may become organized enough to produce severe hail, damaging wind gusts, excessive rainfall, or a low tornado threat.
Severe weather is not expected everywhere, but some areas inside the risk zone may experience impactful storms.

ENHD

Scattered severe storms likely

ENHD means that scattered severe thunderstorms are likely, with a greater chance of organized and impactful severe weather.

Storms may become strong supercells, bowing segments, or organized clusters.
Hazards may include large hail, damaging winds, intense rainfall, frequent lightning, and an increased tornado risk depending on low-level shear and storm mode.

MDRT

Numerous or significant severe storms

MDRT means that numerous or significant severe thunderstorms are possible or likely.

This level is used when confidence is higher that severe weather will be widespread, intense, or potentially dangerous.
Storms may produce very large hail, widespread damaging winds, flash flooding, or tornadoes.
Organized systems such as supercells, MCSs, or QLCS/bow echoes are possible.

SEVR

Highest CESTOF risk level

SEVR means that a major severe-weather event is possible or likely.

This risk is reserved for high-end setups where significant, widespread, or dangerous severe weather may occur.
Hazards may include destructive hail, widespread damaging winds, strong tornadoes, or major flash flooding.
Public impact and forecast confidence are both high enough to justify the top category.

Hatched areas

Hatched

A hatched area can be used inside SLGT risk or higher.

A hatched area means that a more significant severe-weather threat is possible within the risk zone. This may be used when the environment supports stronger or more organized hazards, even if the overall coverage does not justify a higher main risk level.

Hatching may be used for threats such as large hail, damaging wind gusts, excessive rainfall, or a locally increased tornado potential.

Double hatched

A double hatched area can be used inside ENHD risk or higher.

A double hatched area means that a high-end or potentially dangerous severe-weather threat is possible within the risk zone. It should be used only when the environment supports more significant hazards and confidence is high enough to highlight the area separately.

Double hatching may be used for threats such as very large hail, widespread damaging winds, intense rainfall, or a stronger tornado threat.

Hazard forecast maps

The forecast map can show the overall risk or a specific hazard. The hazard layers help explain what type of severe weather is driving the forecast.

General

Main thunderstorm and severe-weather risk. This is the headline category.

Tornado

Areas where low-level shear, storm mode, boundaries, and instability may support tornado potential.

Hail

Areas where storm structure, instability, lapse rates, and shear may support severe hail.

Severe wind

Areas where storms may produce damaging straight-line winds, bowing segments, or organized wind swaths.

Hazard probabilities are not a promise that a hazard will happen at one exact point. They highlight where the environment and storm mode make that hazard more possible.

Forecast matrix explanation

CESTOF uses a simple matrix to help translate storm intensity and probability/confidence into the main risk category. The final polygon can still be adjusted by the forecaster based on storm mode, timing, uncertainty, public impact, and local details.

Intensity scale

1: weak thunderstorms.
2: normal thunderstorms.
3-4: moderate thunderstorms.
5: strong thunderstorms.
6: very strong/severe thunderstorms.
6 with 30% or higher probability/confidence: severe thunderstorms are strongly highlighted in the matrix.

Probability / confidence scale

<5-5%: low chance or low confidence.
15-30%: moderate chance or moderate confidence.
45->50%: high chance or high confidence.

Probability / confidence Intensity →	1Weak thunderstorms	2Normal thunderstorms	3Moderate thunderstorms	4Moderate thunderstorms	5Strong thunderstorms	6Very strong/severe thunderstorms
>50%High chance / confidence	GNRLGeneral Risk	GNRLGeneral Risk	SLGTSlight Risk	ENHDEnhanced Risk	MDRTModerate Risk	SEVRSevere Risk
45%High chance / confidence	GNRLGeneral Risk	GNRLGeneral Risk	SLGTSlight Risk	ENHDEnhanced Risk	MDRTModerate Risk	SEVRSevere Risk
30%Moderate chance / confidence	GNRLGeneral Risk	GNRLGeneral Risk	SLGTSlight Risk	ENHDEnhanced Risk	MDRTModerate Risk	SEVRSevere Risk
15%Moderate chance / confidence	TSTMThunderstorms	GNRLGeneral Risk	SLGTSlight Risk	SLGTSlight Risk	ENHDEnhanced Risk	MDRTModerate Risk
5%Low chance / confidence	TSTMThunderstorms	TSTMThunderstorms	GNRLGeneral Risk	SLGTSlight Risk	ENHDEnhanced Risk	MDRTModerate Risk
<5%Low chance / confidence	TSTMThunderstorms	TSTMThunderstorms	TSTMThunderstorms	GNRLGeneral Risk	SLGTSlight Risk	ENHDEnhanced Risk

How CESTOF forecasts should be used

1Check the risk color

Start with the overall risk level to understand the expected severity and coverage.

2Check hatching and hazards

Look for hatched areas and the tornado, hail, and severe-wind layers to see the main threats.

3Read the discussion

The discussion explains the reasoning, uncertainty, storm mode, and most likely timing or region.

CESTOF forecasts are unofficial amateur forecasts for awareness. They are not official warnings. Always follow official warnings and instructions from national meteorological services and emergency authorities.

Risk color summary

Code	Meaning	Typical wording
TSTM	Thunderstorms possible	Severe weather not expected to be widespread or organized.
GNRL	Thunderstorms likely with isolated severe chance	Low-end, isolated, mostly short-lived severe hazards.
SLGT	Isolated to scattered severe storms possible	A few organized storms may produce impactful hazards.
ENHD	Scattered severe storms likely	More organized and impactful severe weather possible.
MDRT	Numerous or significant severe storms possible/likely	Higher confidence in widespread, intense, or dangerous severe weather.
SEVR	Major severe-weather event possible/likely	Highest CESTOF risk level for high-end setups.