The Caribbean Synoptic Chart shows that yesterday’s low pressure system has moved west and into the Pacific.
However, that double red line, upon which the low pressure system is sitting, moves right through our area.
I first noticed this double red line at the beginning of the month, when I was paying attention to rain. That day, it was labeled monsoon trof and I made note of that and just left it there. I made a mental note, though, that the double red lines were similar to the symbol for the Intertropical Convergence Zone – the difference is that the ITCZ has hatched lines between the solid red lines.
So today I looked up monsoon trof and found it is a standard meteorological abbreviation for monsoon trough. It is “that portion of the Intertropical Convergence Zone (ITCZ) which extends into or through a monsoon circulation.” (wikipedia) I found the following remark particularly interesting:
The term “monsoon trough” is most commonly used in monsoonal regions of the Western Pacific such as Asia and Australia. The migration of the ITCZ/monsoon trough into a landmass heralds the beginning of the annual rainy season during summer months. Depressions and tropical cyclones often form in the vicinity of the monsoon trough, with each capable of producing a year’s worth of rainfall in a relatively short time frame.
So, here we are. The beginning of the rainy season. It’s official.
Related articles
- Flight 447 and the ITCZ [Greg Laden's Blog] (scienceblogs.com)
- 2,300-year climate record suggests severe tropical droughts as northern temperatures rise (eurekalert.org)
