# Silent Heavy Precipitation on Madeira on 1 October 2009

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## Chapter I: Introduction

### Table of Contents

- Chapter I: Introduction
- Introduction

### Introduction

On 1st October 2009 almost 60 mm of precipitation have fallen in 6 hours (16-22 UTC) on a mountain station in Madeira Island (Areeiro, with a height of 1510m), which fitted the orange warning criteria (40 to 60 mm in 6 hours) used at the time at the Portuguese Met. Service (Figure 1). In a 24 hour period (12UTC on 1/10/2009 to 12 UTC on 2/10/2009) a total amount of 101 mm was recorded at the same weather station. An old large-scale low-pressure system was located over the Azores, to which a clear convective activity was related. These convective events were taking place to the northwest of Madeira Island and no special signal could be detected in satellite imagery at a first look over the island (Figure 2). Therefore, this episode could be considered to be kind of "silent" for this mean of observation.

Figure 1: 1 hour precipitation at Areeiro AWS between 8 UTC on 01/10/2009 and 8 UTC on 02/10/2009.

Figure 2: Air Mass RGB on 01/10/2009 at 18 UTC. Red circle around Madeira Island.