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Guess Start of Rainy Season

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So rain now can´t be part of the "rainy season", do they make that same distinction with snow falls, that can´t be part of the "snowy season"?  Only if everything is in a certain alignment?

If it rains, it rains, and if it don´t, it don´t.  What difference does that make to the rainfall total for the year?  Are we supposed to pretend that no rain has fallen the last few days?

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Let Google be your friend and look up "Mexican Rainy Season."  Plenty of discussion there that defines and explains it.  It is marked by a distinct shift in weather patterns and air flow.  For purposes of this exercise when that shift occurs and is accompanied by significant and repeated rain, that defines the start date.

For this year, the beginning has been forecast to be erratic so defining a single start date could be dicey.  Thus far we've had several rains due to tropical disturbances passing to the south of us that have produced most of the rain to the south and mostly cloudiness here.  That actually is typical of a late season pattern when the easterlies are waning and is unusual but welcome this early.



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Our rainy season comes from the south. It happens all over the world this time of year. Most of the world refers to it as the monsoon. It's simple enough to understand. As the planet tilts its north axis toward the sun, the northern hemisphere warms and more moisture evaporates into the atmosphere. As the tilt increases, the tropical weather zone moves northward along with the increased warming. This explains why the rainy season arrives in southern Mexico about a month earlier than our own rainy season. It also explains why we typically get rain during the evening during the rainy season...cooling temperatures in the evening force the excess moisture in the atmosphere to condense into rain. Occasionally, storms develop that are strong enough to spin off and head north on their own ahead of the system. Both the rainy season and the occasional storm originate in the same weather system, which comes from the south. And it has arrived. Welcome rainy season.



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Sorry but that is not correct.  If it were the tropical storms wouldn't move from east to west/northwest.  Our rainy season comes from the SE, driven by the Azores High.

The Monsoon Trough flows from east to west, see below, and as the rain picks up tropical waves track along it from southeast to northwest and it shifts more to the north bringing the rain inland.  That pattern is beginning now as can be seen from this screenshot from the Mexico 3 Day.

Towards the end of the rainy season, usually in September, the tropical storms start tracking more to the north and northwest, some curving around to hit the coast as far north as Cabo.

No, the rainy season has not started.  We are in a drying trend now as the residual moisture from two tropical depressions dissipates.  But it is coming soon as the screen shot illustrates.


Screenshot (55).png

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On 5/15/2021 at 3:43 PM, Mainecoons said:

In order to be deemed a real start, the rain has to fall three times in a week, be clearly generated by the easterlies the shift of which denoted the beginning of our season and have to add up to 3.8 cm (1.5 inches) in the first 7 day week.  The date of the first rain in the qualifying trio is the winner.

We all agreed on this thread to go by these "rules", so everyone give it a rest.      MC has done this for years and has this covered.   

If you want to change the game next time, then speak up earlier.

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5 hours ago, Mainecoons said:

Nope.  You're about to be on the sidelines watching with the rest of us early optimists.


What happens if / when we're ALL early?  😉

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