29 December 2012

Second Rainiest Year for Miami

This is a little off-topic from the usual hurricane updates, but I thought it was an interesting tidbit from the hurricane hotspot of Miami.  I hope you find it interesting too!

When you think of southern Florida, you think of a tropical climate... with year-round warm weather, exotic flora and fauna, beautiful beaches that seem to go on forever, and copious amounts of rain. So when a tropical location like Miami nearly breaks its all-time record annual rainfall total, that's really a LOT of rain.

There are essentially just two seasons in Miami: the drier cooler winter (approximately November through April) and the humid hot summer (approximately May through October). Climatologically, about 75% of the city's rainfall comes during the summer, and the average annual total rainfall is 61.9”. This map shows the average precipitation across the country so you can find your favorite city (the averages used throughout the post are the standard 1981-2010 “climate normals”, and the rainfall amounts listed for Miami are from the Miami International Airport).

This year, while a huge portion of the country suffered from extreme drought conditions, Miami got off to a wet start, and it just kept coming. By the beginning of April, Miami was at 125% of average rainfall, and by the beginning of July, up to 174% and the second wettest year on record for the January through June period. For the January through September period, Miami's 2012 total rainfall was 79.5”, the wettest such period on record by a healthy margin. At year's end, it's at 86.94”, or 140% of average... very close to breaking the record of 89.33” set in 1959.  By the way, 87" is 7'3" for those who think better in feet.

The chart below shows these periods and annual totals graphically going back to 1949*. The annual total is shown in cumulative quarterly increments. The first three months are denoted by the purple bars, the first six months by the green bars, the first nine months by the yellow bars, and finally, the full year by the top of the red bars.
Zooming in to just 2012 and plotting the daily cumulative rainfall amounts against the climate normal clearly shows that from May onward, Miami remained well above average, and frequent events maintained and grew the gap.

* 1949 is used as the start of the data period due to availability and station relocation.  See the first data source below. 
Data sources: