Red sky at night, Shepherd’s delight. Red sky in the morning, Sailor’s warning. I'm not going to argue about shepherds and sailors; that’s not important here. The questions are: “Is it a useful saying? Does is work? If it works, why?” And, “Why is the sky blue?”

Written by Bob McDavitt, Meteorologist

Today’s weather map shows how this cold southerly is being produced by a combination of a HIGH or anticyclone in the Tasman Sea, and a LOW or depression between Canterbury and the Chatham Islands. For want of a better phrase, we could call this an eggbeater southerly.

May 4th/5th 2009

I work as a public forecaster and my main tasks include writing regional, urban and mountain forecasts. I either work mornings (which start at 5:50AM and finish mid afternoon), or afternoons (which commence mid afternoon and run until 10:45PM).

Several years ago, while on a trip to the UK, I noticed something of meteorological interest that was not in the sky. I was outside Westminster Abbey, one of the worlds greatest landmarks, and the burial place of many famous people. Sir Isaac Newton, a man who had a profound influence on all branches of science (including atmospheric science) being one such esteemed individual. As I walked around the Abbey, I noticed a plaque that nicely describes what mariners might call "variable 10 knots"...

With clear skies over most of Canterbury on Monday May 11th 2009, there was  a good look at the fresh snow that fell the previous day, Sunday (10th May).  Here's the view late Monday morning  (around 10:30am) from NASA's Earth Observing System Terra Satellite,

Fresh snow on the Alps and Canterbury foothills - as @ Monday 11 May 2009. (Image courtesy of MODIS Rapid Response Project at NASA/GSFC.)

Cumulonimbus cloud is not a common part of the Wellington cloudscape ...

With rainfall well above normal this winter, it has been a great time for slips: big ones cutting major road and rail links in Kaikoura and other places and thousands of little ones making small mischief on roads and properties all over the country. Houses in Auckland have been threatened for days by slow moving slips, while, in Milford Sound, tourists watching waterfalls had to sprint to safety when the sound of the rain took on a deeper rumble and tonnes of rocks and trees crashed down on the spot where they had been standing.

Clouds

This change-of-colour amongst the trees moves from south to north in tune with decreasing day-length. The intensity and duration of "autumn colour" depends on the weather as we slide slowly into the darker months.

March 23 is WORLD METEOROLOGICAL DAY.