The monsoon trof (meteorology-speak for trough) is now well north of us.
But the AVN color satellite shows lots of stormy activity in the Pacific.
Hidromet is predicting intervals of stormy rain this afternoon for Chiriqui. Looks like a safe bet.
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.
Today’s forecast is for pretty clear weather in Chiriqui.
The visible satellite image shows few clouds in our area. The big threatening ones are in the Caribbean and in the Pacific off eastern Panama.
But there’s that low pressure system hovering over the country in the Caribbean Synoptic Chart.
It’s a bit nasty-looking, but it does look from the forecast like it will affect eastern Panama and, fingers crossed, not us.
The results are in for May – roughly 25 inches of rain, above average but no maximum. The full report is found under the Reports menu.
Overcast and rainy days are continuing. It’s safe to say that the rainy season has begun and we’ll be ready for a break as soon as we can get it.
Yesterday’s low pressure system seems to be moving away from us, and although the Monsoon whatever is still there, conditions seem a little better this morning. I saw blue sky patches earlier and now the sun is shining.
Further encouragement from the satellite images. The AVN shows that the serious rain clouds are all the way across the Caribbean, near Hispanolia. The ones in the Pacific are few and are pretty far offshore for now. Later in the day they may move in, but for now we can enjoy what we have!
We had an aguacero yesterday afternoon, followed by almost continuous rain through the night until about 2:00 this morning. A total of nearly 3 inches.
I was too busy to look at the weather situation yesterday, but when I saw the Caribbean Synoptic Chart this morning, I fully understood why we had rain, and why it has returned as I write.
There’s that low pressure system moving north. I’d guess that it was over us yesterday. The low pressure system has a famous orange dashed line through it, suggesting a meteorological trough, and, naturally, rain.
Then there is that double red line labeled Monsoon Trof. Whatever that is looks pretty grim, although at the moment, thank goodness, it’s over northern Costa Rica, not Panama.
Finally, two Tropical Waves (solid orange lines) are approaching us. In some areas, tropical waves can generate tropical cyclones, but probably not here in Panama.
The satellite image shows just how cloudy the entire area is, and how unlikely it is that we’ll have a beautiful day today.
A neighbor called last night to ask about the dashed orange lines on the Caribbean Synoptic Chart. I didn’t know, but I did remember reading about Tropical Waves and I thought they might have something to do with that.
I was wrong, but I couldn’t look it up until just now because we were without internet all morning.
It turns out that orange dashed lines indicate a surface trough, which “…is an elongated region of relatively low atmospheric pressure, often associated with fronts.” (Definition of trough (meteorology) in Wikipedia.)
So we might expect some rain along those orange dashed lines, and indeed, today, we’ve already had some.
The Intertropical Convergence Zone is not showing up this morning on the Caribbean Synoptic Chart.
However, just before sunrise, there were clouds in the area where one would expect the ITCZ. An interesting streak of clouds is running NE-SW across Puerto Rico and the Caribbean, possibly associated with the edge of the stationary front in the Bermuda Triangle area, shown in the synoptic chart.
Hidromet predicts light showers this morning for Chiriqui.
Even though the ITCZ is running right through the Pacific slope of Panama, with a low pressure system on either side of the country,
the forecast is for a sunny morning in Chiriqui. The rain, possibly aguacerros, will likely come this afternoon.
This is a pretty typical rainy season pattern.
Yesterday’s low pressure system seems stalled off Costa Rica.
We can probably expect weather a lot like yesterday’s – cloudy but little rain.
