Apr 5, 2012

Battle of the Cold Front and Spring ET

Word is on Friday we could see a front.

The result could be some coveted spring rain.

Foreground: In the foreground is actual weekly rainfall (blue bars), average weekly rainfall (dotted black line) and median weekly rainfall (solid black line).  The dotted line nicely shows that on any given dry season week, i.e from Columbus Day to Memorial Day, seeing no rain is actually the norm.  Compare that to the summer when the median weekly rainfall expectancy, i.e. 7-day running summation, is consistently at or over 1 inch.   Background: The background color coding shows the typical wet season (light blue) and dry season (red). The wet season is more than just rain, however. It is better described as “high rain and high evapotranspiration (ET) season.” In the same way, the dry season is more than just lack of rain. The winter months of the dry season can be described as “low rain and low ET” whereas the spring months, and in particularly April and May’s first half, can be described as “low rain and increasing ET.” Synthesis: This year’s heaviest rains came at the end of the wet season (October), just as ET was starting to slow down. Now that ET is heating back up, periodic rains become more and more vital for keeping the water table up and low areas wet.


But will it be enough to matter?

Evaporation, not rainfall, plays the biggest role in April. Thus, lack of rainfall, only impartially at best tells where April fits in south Florida's seasonal water cycle. It’s the incessant sun and greening out tree foliage and ground cover, i.e. output of water to the atmosphere, that -- not until the regular summer rains -- can the input of wet season atmospheric water, i.e. afternoon thunderstorms, ever hope to keep up.

Could one of these be on the way?

That being said,

We are not in the business of turning down rain.


At this point, the swamp will take whatever water it gets!

1 comment:

Robert Sobczak said...

Note: The chart above does not yet include Thursday's or Friday's rain.