This text is part of the Weather Preparedness & Resilience Toolbox developed by the YOUROPE Event Safety (YES) Group within YOUROPE’s 3F project (Future-Fit Festivals). It is aimed at everyone involved in planning, building, and operating open-air events. It helps festivals and other outdoor events become truly weather-ready by offering both practical and research-based resources as well as background information on weather and climate. Learn how to design safer and more weather-resilient outdoor events.

Forecasting vs. Nowcasting

In practice, forecasting and nowcasting are complementary, not competing approaches:

• Forecasting sets the context: elevated risk, staffing levels, readiness.
• Nowcasting triggers decisions: hold, evacuate, resume, or stop operations.

Many weather-related incidents at events occur not because the forecast was wrong, but because nowcasting information was missing, misunderstood, or not acted upon in time.

In short:

• Forecasting tells you what might happen.
• Nowcasting tells you what is happening — and what will happen next, fast.

Forecasting refers to predicting future weather conditions hours to days (or longer) in advance, primarily using numerical weather prediction (NWP) models.

Core characteristics

• Time horizon: ~6 hours to several days (sometimes weeks)
• Primary data sources:
  • Global and regional NWP models
  • Initial conditions from satellites, radiosondes, surface stations
• Strengths:
  • Strategic planning and scenario development
  • Anticipating synoptic-scale systems (fronts, heatwaves, storms)
• Limitations:
  • Increasing uncertainty with lead time
  • Limited precision for local, short-lived phenomena (e.g. single thunderstorms)

Typical questions forecasting answers

• Will a storm system affect the region tomorrow?
• Is there an elevated risk of heat stress during the festival weekend?
• Should contingency plans be prepared for high winds?

Nowcasting

Nowcasting focuses on the very short term, describing what is happening now and what is likely to happen in the next minutes to ~2–6 hours, based on real-time observations.

Core characteristics

• Time horizon: Immediate to ~0–6 hours (often 0–2 hours)
• Primary data sources:
  • Weather radar (precipitation movement and intensity)
  • Lightning detection networks
  • Satellite rapid-scan imagery
  • On-site sensors (wind, temperature, rain)
• Strengths:
  • High spatial and temporal resolution
  • Excellent for fast-evolving, local hazards
• Limitations:
  • Little insight beyond the very short term
  • Not suitable for long-range planning

Typical questions nowcasting answers

• Will lightning reach the site within the next 30 minutes?
• Is this rain cell intensifying or weakening right now?
• Do we need to suspend stage operations immediately?

Learn more about Nowcasting: https://youtu.be/_ma7BpJC-AI?si=EaF2LbVeNavjrXbp