An atmospheric river brought a surge of high precipitable water (PW) air into Ireland and the United Kingdom on 18-20 November 2009 (Fig. 1). Preliminary reports suggest record rainfall was observed over Ireland, northwestern England and southwestern Scotland from 18-20 November 2009. The United Kingdom Meteorological Office (UKMO) indicated a storm on 13-14 November and 19-20 November impacted Britain. The focus here is on the event of 19-20 November. Initial reports suggest as much as 300 mm of rainfall may have fallen. The extreme heavy rainfall produced flooding in the Cumbria area of Britain. Similar atmospheric rivers (Ralph et al 2006 & 2005) have been observed along the West Coast of the United States. When these plumes of high PW air impinge upon land, interact with sloped frontal boundaries or interact with elevated terrain, they often produced heavy rainfall. The impact of moisture laden air and above normal PW standardized anomalies (Grumm and Hart 2001) into the West Coast of North America was documented by Junker et al (2008). They demonstrated the value of standardized anomalies of fields such as PW, winds, and moisture flux (MF) in defining areas where heavy rainfall would fall. Stuart and Grumm (2007) showed the value of standardized anomalies in defining and identifying heavy snow events in the eastern United States. Ensembles..PW...anomalies...Heavy rainfall