Simon will bring some rain to Southwest as Caribbean shows signs of development – or not

Tropical storm Simon in the east Pacific is continuing to weaken at a rapid pace. It won’t be long until it becomes just a remnant area of low pressure as it tracks towards the Baja peninsula.

Fortunately, Simon is smaller in size than Odile was and thus the deep tropical moisture is more limited. This means that even though heavy rain is possible for parts of the Southwest, particularly southeast Arizona and points east, it does not look like a very high impact event.

According to the discussions that I have read, perhaps an inch or so of rain could fall in the heavier cells that manage to develop but that is about it. Contrast this with the remnants of Odile which had the potential of dropping up to nine inches of rain in the mountains of the Southwest. It’s something to keep a close eye on if you live in or are traveling through the area but don’t expect a major widespread event to unfold.

Now we need to turn our attention to the Caribbean Sea. For several days in a row, the GFS computer model has developed a tropical cyclone in the southwest Caribbean Sea, moving it north with time and in to the Gulf of Mexico.

Other models are showing this scenario as well to one extent or another.

ECMWF model showing weak development in the east Pacific in five days

ECMWF model showing weak development in the east Pacific in five days

On the other hand, the one model that has yet to join the chorus is the ECMWF (Euro). Instead of development in the Caribbean Sea, this model develops something on the other side of Central America, in the east Pacific. This is where the NHC currently has a yellow area outlined for low probability of development over the next five days. It is interesting to see that the Euro has quite a weak system in the Pacific and never develops it much, so it’s not as if the Euro is blowing up a powerful hurricane on the other side of Central America.

GFS model showing same time frame but with development in the western Caribbean instead

GFS model showing same time frame but with development in the western Caribbean instead

Contrast this with the latest run of the GFS, the main U.S. generated global model. At day five, we see a fairly well developed tropical cyclone in the western Caribbean Sea. This fits with climatology which suggests that this region is prime for development this time of year. Water temps are also plenty warm. I think that the GFS has had too many false-starts this season and despite run after run showing development in the Caribbean, it is being discounted for now.

I suspect that we will know for sure over the next few days. If we do not see anything begin to develop in the southwest Caribbean then I suppose it means that the GFS model was “wrong” so to speak. However, with other models showing Caribbean development, I would not be surprised to see something get going before the end of the week. As I said, we would normally be watching this region in October anyway, so it makes sense at least from a climatological perspective. As they say, stay tuned, not sure how this one is going to end.

I’ll have an update on all of this tomorrow.

M. Sudduth 1:5 PM ET Oct 6


About Mark Sudduth

Greetings! I am Mark Sudduth, the founder and editor of The site began in 1999 as a way to post info concerning tropical storms and hurricanes for any interested visitors. Little did I know how big it would become in the years since. Now, we have millions of visitors from all over the world who have come to rely on the site as a no non-sense, tell it like it is resource for all things hurricane related. We are supported by a combination of corporate sponsors and our loyal Client Services members who subscribe to premium content on our sister site, I am married with six energetic and intelligent children and live in southeast North Carolina. I graduated UNC-Wilmington in 1995 with a BA in Geography and have studied the effects of hurricanes on our society ever since.
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