Periods of heavy rain, and amounts may approach warning criteria. If warning amounts of rain do accumulate they are most likely from late Wednesday morning. Also note there is a risk of downpours bringing hourly rainfall intensities of 25 to 40 mm about Great Barrier Island and Auckland north of the Harbour Bridge from Wednesday afternoon. Impact: Streams and rivers may rise rapidly. Surface flooding, slips, and difficult driving conditions possible. Chance of upgrading to a Warning: High. Changes: Note that the chance of upgrade to an Orange Warning for Great Barrier Island and areas north of the Harbour Bridge is high but moderate elsewhere.