A new tropical storm is likely developing in the southeast Pacific not too far off the Mexican coastline. The National Hurricane Center will almost certainly begin advisories on the system later today (right now it is designated at invest area 97-E). The development of this soon-to-be-storm is important for a couple of reasons.
First and foremost, it will have a direct impact on the weather across portions of Pacific Mexico over the next few days. Heavy rain with the usual threat of mudslides and flash flooding will an issue due to the fairly close proximity to the coast.
Computer models indicate that a track to the west with a gradual bend back to the northwest and eventually northeast is probable over the coming days. This means that there is the threat of a hurricane making landfall in Mexico as the system is forecast to intensify significantly over the very warm waters of the southeast Pacific. Interests along the coast of Mexico should pay close attention to this developing storm. It would not surprise me at all to see a hurricane watch posted for a portion of the Mexican coastline by sometime tomorrow.
The other interesting aspect of this system is where it developed. Right now it is situated just south of the Gulf of Tehuantepec which is itself not far from the Bay of Campeche in the extreme southern Gulf of Mexico. If you remember your geography, the strip of land that separates the two bodies of water is called an isthmus. The developing storm is on the Pacific side of the isthmus and likely precluded any development from taking place in the southern Gulf of Mexico. It is rare to have two tropical cyclones going at the same time so close together – and as such, the Pacific disturbance took over and is now on its way to becoming yet another hurricane for the region.
However, something very interesting may happen down the road. Tropical cyclones are incredible heat engines, driving their convective bursts with warm water. The transport of this energy in to the subtropics can often times lead to larger storms that have part hurricane, part mid-latitude cyclone characteristics. There is a chance that we see that happen with the Pacific system after it makes landfall in Mexico.
Some of the global models are indicating that at least some of the remnant energy will survive the trek across Mexico and combine with an upper level low coming out of the Southwest to produce a potentially heavy rain event for Texas and New Mexico. While the rain is needed, we could be faced with another instance of too much, too soon. The latest forecast from the WPC (Weather Prediction Center, formally known as the Hydrometeorological Prediction Center) suggests that a wide swath of Texas and part of eastern New Mexico could receive several inches of rain beginning later in the week. The timing of when and where is tough to call this far out but your local NWS office will have the best info concerning local impacts from this rain event.
Remember back in April and in to May, parts of Texas were inundated by very heavy rain as wave after wave of energy moved across the region dumping incredible amounts of water, resulting in widespread flooding issues. While this storm will not be nearly as prolonged, there is potential for more flooding so please pay close attention as the week wears on.
As I mentioned in the headline, the Atlantic Basin remains very quiet right now. I do not see any solid evidence of development happening anytime soon. It appears that a slow moving MJO pulse will eventually make its way in to the region as we get in to early November and it’s possible that we could see more activity flare up at that point, probably in the western Caribbean Sea. We’ll deal with that when and if the time comes.
I’ll have more in the developing storm in the southeast Pacific on my video discussion later today.
M. Sudduth 8:45 AM ET Oct 20