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

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Dangerous hurricane Odile heading closer to the Baja peninsula, likely to spread more flooding rain in to Southwest U.S.

Powerful hurricane Odile off the Baja peninsula

Powerful hurricane Odile off the Baja peninsula

Hurricane Odile in the east Pacific has strengthened significantly over the past 24 hours and is now a solid category four. This is an extremely dangerous hurricane capable of inflicting serious wind damage as well as accompanying heavy rain, storm surge and enormous waves. People along the southern Baja peninsula should be ready by now, if not, time is running out quickly.

The forecast track keeps the core of the hurricane just off the extreme southern part of the Baja, sparing Cabo San Lucas the worst of the category four winds. However, hurricane force winds are likely to occur and any deviation to the east would bring the eyewall that much closer to the coast. Indeed, it will be an interesting and potentially frightening night along the southern Baja peninsula.

Further up the coast, conditions should be less intense as the hurricane begins to weaken over cooler water, partly due to being disturbed by category three hurricane Norbert just last week. Never the less, the entire southern region of the Baja is at risk from this hurricane and preparedness measures need to be taken. From what I am seeing, a category four hurricane has never passed this close to the area – it needs to be taken very seriously.

Seven day total precip for Southwest U.S. showing large area of 1-2 inches of rain

Seven day total precip for Southwest U.S. showing large area of 1-2 inches of rain

Once Odile moves northward over the coming days, its circulation will begin to push deep tropical moisture in to the Southwest U.S. setting the stage for another possible high-impact flood event next week.

After dealing with the rains from Norbert, coupled with Gulf of Mexico moisture being funneled in around a large high pressure area, this part of the country is vulnerable to serious flooding issues throughout the week ahead.

It is important for people living in or traveling to the area to monitor local National Weather Service information. If you have a Smartphone, use it to stay up to date on the latest information. It won’t be long now before flash flood watches are posted for the region. We could be looking at several days of heavy rain setting up and the problem is, it is impossible to know precisely which locations will get hit the hardest with rain.

Once again, I am heading out West to cover the event. I spent several days out there last week and learned a lot about how the desert interacts with tropical cyclone moisture. It is not something to mess around with. We saw instances where I-15 was washed out northeast of Las Vegas, almost taking the lives of several people who were caught up in the flash flood. Phoenix set its all time rain fall record during this past event with numerous flooding issues and a dust storm. Areas from southern California through southern Nevada, southwest Utah and most of Arizona could be impacted by slow moving, torrential downpours as the week progresses. Flooding is a major concern and I will be in the region to provide live coverage via our Ustream channel and for The Weather Channel. I cannot emphasize enough how important it is for people to realize that tropical cyclones are not just about wind or storm surge. They have several weapons that they can hit you with and rain is most certainly one of them. Be aware and keep up to date on the very latest. I will post frequent updates to our app, Hurricane Impact, which include video blogs in the video section. I never thought I would be covering more hurricane related activity out West than I am along the East Coast or Gulf Coast but here we are – it’s that type of year.

In the Atlantic, hurricane Edouard is forecast to become the season’s first major hurricane but it will remain well out in the open Atlantic, bothering only shipping interests. One weather geek factoid about it – we’re likely to see quite a few ACE points pile up with Edouard as it looks to remain on the map for several days to come. ACE or Accumulated Cyclone Energy is the measure of how much energy a hurricane season outputs based on each individual tropical storm or hurricane. The typical ACE number for the Atlantic is around 100-103 in any given season. Right now, we are in the low 20s but are climbing now due to Edouard. We ended last season around 36 I believe and it’s possible that Edouard will allow this season to eclipse last year, especially if Edouard becomes a major hurricane and stronger than forecast. It’s just something I like to keep track of as it tells me much more about the quality of the season instead of the numbers of named storms, etc.

Elsewhere in the Atlantic, nothing to be concerned with for the time being though I cannot imagine that we will go the entire month of September without something forming in the Western Caribbean or Gulf of Mexico. Long range models are sketchy at best but some do indicate activity brewing within about 10 days in the Western Caribbean or Gulf. No matter how quiet a season is, you never turn your back on it.

I’ll post more here in the morning including details about the field work coming up for the Desert Southwest this week.

M. Sudduth 2:32 PM ET Sept 14

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