Tropical Cyclone Rainfall: Forecasting and Communication

Rainfall forecasting and Communications
    • Enrollment Information:


Tropical cyclones (TCs) can bring excessive rainfall and create large precipitation gradients within very short distances. The excessive rainfall can lead to long-term flooding well beyond the TC impact period. This requires forecasters to issue specific flood products to increase public awareness and initiate protective action.

When a TC threatens communities, National Weather Service (NWS) and Weather Prediction Center (WPC) forecasters share information with local decision-makers regarding plausible rainfall scenarios, uncertainties, potential threats and impacts.

This course will introduce forecasters, decision-makers, and others interested in TC rainfall to:

  • the challenges in predicting precipitation associated with TCs
  • the deterministic and probabilistic rainfall forecast products issued by the WPC to forecast TC-related precipitation
  • the different interpretations of probabilistic products from the WPC and National Hurricane Center
  • the need for collaboration between national centers to ensure a unified message

The lessons in the course provide practice in:

  • assessing the heavy rain potential and identifying the areas most likely to be affected
  • interpreting national center and local Weather Forecast Office (WFO) forecast guidance correctly and communicating the precipitation threat
  • identifying situations when a Flash Flood Emergency should be issued
  • collaborating with WPC and other WFOs in issuing TC rainfall forecasts

Goals and Objectives

The main goal of the course is to introduce forecasters, decision-makers, and others interested in tropical cyclone (TC) rainfall to the factors contributing to heavy TC rainfall, the deterministic and probabilistic forecast products used to predict it, and how to best communicate the forecast guidance.

Learners who complete the course will be able to:

      • Describe the unique challenges of TC quantitative precipitation forecasting.
      • Explain how TC characteristics (track, intensity, forward speed) and terrain can affect TC precipitation distribution and magnitude.
      • Differentiate between the way WPC and NHC use probabilities in their products.
      • Use WPC QPFs, PQPFs, and Excessive Rainfall Outlooks to determine the location and amount of greatest precipitation, and the confidence in these forecast parameters.
      • Determine the potential flood impacts of a TC upon a WFO’s local area of responsibility.
      • Craft clear and concise communications for decision support based on deterministic and probabilistic forecast guidance.

The knowledge and skills covered in the course will assist forecasters in providing better decision-support. Emergency managers and others will become familiar with the deterministic and probabilistic forecast products, and the uncertainty associated with TC rainfall forecasts.

In addition, all lessons offer their own specific objectives which can be found on their respective description pages.


This course has two lessons. The first lesson, “WPC Rainfall Guidance for Tropical Cyclones” introduces learners to the challenges in predicting precipitation associated with tropical cyclones (TCs). It also provides an overview of the deterministic and probabilistic rainfall forecast products issued by the Weather Prediction Center (WPC) to forecast TC-related precipitation. The second lesson, “Local Tropical Cyclone Precipitation Forecasting and Communication” introduces learners to the challenges in predicting and communicating localized TC rainfall threats. The lesson discusses the key ingredients conducive for heavy TC rainfall, and the tools used by the National Weather Service to forecast it.

Each lesson has an accompanying assessment that learners must pass in order to receive credit for the particular lesson.  The course includes between 1.5 and 2 hrs of instructional time (not including the assessments).

Course Outline

Additional Resources

Course Outline