Archive for 95L

Tropics of little concern across Atlantic Basin, not so much for west Pacific

Track map of typhoon Usagi in the western Pacific

Track map of typhoon Usagi in the western Pacific

This weekend will be wet in some places across the Southeast and Gulf Coast but not because of any tropical storms or hurricanes. Things are beginning to slacken up quite a bit as we head towards the end of September.

The NHC has lowered the chances of development for invest 95L in the western Gulf of Mexico. Computer models still indicate that a weak low will take shape from this system which could have some strong winds and heavy rains associated with it but nothing purely tropical. The good news is that a healthy dose of rain is likely for areas from Texas across to the Carolinas though some areas could receive a little too much too soon.

Meanwhile, a weak area of low pressure is trying to develop well east of Florida and could become what is termed a subtropical cyclone as it moves to the north with time. Interests in Bermuda want to pay attention to this feature as it could bring rain and an increase in wind over the next few days.

Way over in the western Pacific, a powerful typhoon, Usagi, is closing in on southern Taiwan today where excessive rain is likely to fall due in part to the lifting of the moisture associated with the mountainous terrain there. It looks like the core of the typhoon will pass far enough south of Taiwan to keep the worst conditions offshore.

Then, early next week, Usagi is expected to make landfall in China, possibly near Hong Kong as a strong typhoon but probably weaker than it is currently.

I’ll have posts throughout the weekend.

M. Sudduth 2:15 pm ET Sept 20

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Complex pattern shaping up for Gulf of Mexico, could lead to more rain for areas drenched by Ingrid

A look at various computer models shows the complex situation with 95L

A look at various computer models shows the complex situation with 95L

There’s nothing much new happening with invest 95L this morning. The loosely defined center is located over the Yucatan peninsula with limited deep convection associated with it. The NHC notes that conditions are favorable for some development once the low emerges in to the SW Gulf of Mexico. The global models generally agree with this scenario and show some organization over the next few days as the low moves slowly westward. This could lead to even more rain for portions of Mexico where hurricane Ingrid made landfall recently.

As you can see from the graphic, the computer models are not in agreement as to where the system will track over the coming days. The pattern is complex and there is no easy answer for what may happen with this system.

One interesting item of note – the two most reliable global models, the ECMWF and the GFS, both show very little in the way of strengthening with this system once it is over the Gulf of Mexico. On the other hand, the UKMET model, another fairly reliable global model, shows modest strengthening with a track towards Mississippi. As usual, the hurricane-specific HRWF model creates a strong hurricane out of the situation, something that I simply cannot believe at this point.

It looks like the global models are depicting the energy from the low pressure area getting strung out over a wide area and thus it never has time to focus and thus we see a weak storm at best. Complicating matters is what appears to be a low pressure area that develops across the southern tier of the U.S. that itself moves along the northern Gulf Coast and Southeast, finally moving offshore of the Carolinas. This is more like what we see in winter with southern-track storms that bring heavy rain and severe weather with them.

The end result looks to be a rather slow process taking shape with this system. While it is possible that we see something significant come of it, I have my doubts at this point. I believe the more likely scenario is a weak tropical storm forms in the southwest Gulf, mills around for several days and then gets pulled east, strung out and disorganized but a big rain maker. I guess time will tell.

For the next couple of days, the weak area of low pressure will gradually move off the Yucatan and from there we will see what it does. Heavy rain and squally conditions are going to continue for the region as the low moves quite slowly.

Meanwhile, in the eastern Pacific, TD Manuel, which made landfall a few days ago in Mexico, has managed to get back out over the water and is forecast to become a tropical storm again as it too dumps more heavy rain on the Pacific side of Mexico. The NHC forecast takes the soon-to-be storm in to the Baja area and then turns it southward, finally weakening at the end of the forecast period.

It has been a strange hurricane season – one that has featured a few systems that have seemingly died out, only to come back again a short time later. We’ve also not had any strong hurricanes form in either the east Pacific or the Atlantic this season, opposite of what was forecast earlier in the year. However, we’ve seen a lot of rain from landfalling storms and hurricanes and that has been problematic for people who have had to deal with it. We still have a few weeks left of the peak time of the season, at least from a climatological perspective. So far, no intense hurricanes have come along, perhaps it will stay that way. I see nothing in the long range to indicate a change but we do have to deal with what ever comes of 95L. Once we are past that, we may start to slow things down quite a bit, we’ll see. So far, so good.

I’ll post more here this evening on 95L and have a look at the day’s model output.

M. Sudduth 7:40 am ET Sept 18

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Yet another development possible in the SW Gulf of Mexico

Invest area 95L in the western Caribbean Sea has some potential for development once it reaches the SW Gulf of Mexico

Invest area 95L in the western Caribbean Sea has some potential for development once it reaches the SW Gulf of Mexico

As we move past the mid point of the month, the focus will shift more and more towards the western Atlantic Basin and more specifically, the Caribbean Sea and Gulf of Mexico. These areas are climatologically favored as we end September and get in to October. Interestingly enough, we’ve already seen three developments from this region: Fernand, TD8 and Ingrid. I think we could see one more before all is said and done.

The NHC is monitoring a large area of showers and thunderstorms (95L) over the NW Caribbean Sea that is forecast to move in to the SW Gulf of Mexico with time. Most of the global models develop this feature and move it towards, you guessed it: Mexico. This is obviously terrible news for folks there who have had to deal with simply incredible amounts of rain this hurricane season – most recently from Ingrid. What they do not need is another tropical system but it looks as though one may be on the way.

What happens next is where everything gets quite fuzzy. There is a lot of energy available in the Caribbean and Gulf and it’s interesting to see the computer models try to figure it all out. What we see is one run of the models showing a storm heading across the Gulf and in to Florida before turning up the Southeast coast while the next run shows the energy spread out over a large area, never focusing in to one solid tropical cyclone. Either way, it appears that a lot of rain is heading for portions of the Gulf Coast states as this system gets pulled in to the SW Gulf and then develops some. The process looks like it will take five to seven days or more to unfold. While I do not see anything that leads me to believe that we will see a significant event develop for Florida, it’s something to certainly watch over the coming days. As I said, at the very least, heavy rain could be heading that way as this hodge-podge of weather takes shape in the Gulf of Mexico.

Elsewhere in the tropics, the remnants of Ingrid continue to dump heavy rain on parts of eastern Mexico as the low pressure slowly loses its punch over land.

Out in the east-central Atlantic, Humberto remains a tropical storm but should begin to lose its tropical characteristics over the next few days once it turns northward in to the higher latitudes of the Atlantic.

I’ll have more on the potential Gulf development situation with a post this evening.

M. Sudduth 9:00 am ET Sept 17

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Tropics beginning to show signs of that busy spell we’ve been talking about

Satellite shot showing 95L in the Bay of Campeche plus a strong tropical wave emerging from the African coast line

Satellite shot showing 95L in the Bay of Campeche plus a strong tropical wave emerging from the African coast line

This is probably the last weekend that we will have for a while without a named storm on the maps. The tropics are showing signs of getting active, starting with the Bay of Campeche and invest 95L.

The NHC gives the low pressure area a 60% chance of becoming at least a tropical depression before it moves inland over Mexico tomorrow. Satellite imagery shows clearly the circulation associated with the low and it won’t take much for it to become a tropical depression or even a tropical storm. The main impact for Mexico will be torrential rain and occasional gusty winds as the system moves generally WNW towards the coast.

A Hurricane Hunter crew will investigate the area later today and we will know for sure at that point if a depression has formed. Water temps are plenty warm and the upper levels of the atmosphere are favorable for this to develop. The limiting factor is, of course, how much time it has over water.

What ever develops in the region will have no chance of impacting the United States due to a large area of high pressure parked over the Midwest. This “heat dome” as it’s called, is much more dense of an air mass and will thus keep this system suppressed far to the south in the Bay of Campeche.

Meanwhile, we will need to be watching the far eastern Atlantic this coming week for the possibility of development. Several of the more reliable global computer models are indicating that a tropical wave will move off and begin its steady process of developing as it moves westward. The stable air that has been in place for the past several weeks is beginning to modify with deeper moisture beginning to show up. This will help to fuel the convective process and allow pressures to fall and a tropical depression to form by mid-week. The GFS and the ECMWF models both show this scenario though they differ in how quickly it takes place.

The month of August has been unusually quiet but that is likely to change soon and it’s possible that we could have two more named storms and perhaps, just perhaps, the season’s first hurricane if the eastern Atlantic system does in fact develop – all before August ends in a week. Things can change that quickly, we’ve seen it before. I’ll post more on 95L in the Bay of Campeche later today or early this evening once new information comes in.

M. Sudduth 11:06 am ET August 25

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Erick weakens to tropical storm while 95L slowly organizes in the tropical Atlantic

Satellite shot of 95L in the tropical Atlantic

Satellite shot of 95L in the tropical Atlantic

In the east Pacific today, Erick has weakened to a tropical storm as it has moved over cooler water and has probably had its inflow disrupted somewhat by the Mexican terrain. Continued weakening is expected though the storm will bring periods of heavy rain to parts of the Mexican coastline and eventually up to the southern Baja. Fortunately, it looks like Erick will turn westward enough to miss a direct hit on the peninsula and it will be considerably weaker as well. The rest of the east Pacific is quieting down.

In the tropical Atlantic, we are watching 95L very closely as it moves quickly to the west, pushed along by brisk trade winds in the deep tropics. So far, organization has been slow to occur but this tropical wave and associated weak surface low is quite impressive for this time of year.

Water temps along its path are around 82 degrees F along the surface with heat content values in the low range. This means the warm water does not extend very deep in to the ocean which is really not an issue for developing systems like this one.

Looking at the moisture content of the atmosphere in the vicinity of 95L, it is obvious that plenty of what is called “precipitable water” is available as seen here. This should allow the wave to continue to hold its own at the very least and maybe even grow more deep convection and eventually a well defined surface circulation. This is what is needed to be classified as a tropical depression.

Looking at the various computer models, it appears that this system will track through some portion of the Lesser Antilles early next week as it heads generally on a west-northwest track. This means an increase in wind and rain for the region as the wave moves past. If it organizes enough, it could be a tropical depression or even a tropical storm. The intensity models show steady strengthening to a tropical storm within the next 24 to 36 hours. This may be a little fast but then again, it’s possible considering the well organized look to the wave now. All it needs is a little more deep convection and that surface circulation that I mentioned and it could begin to strengthen quicker. Needless to say, interests in the Lesser Antilles should watch 95L closely as it approaches next week.

As far as any potential impact to the U.S. goes, we really need to wait and see if this even develops. The global models are not showing anything significant just yet and until they do, I am not going to be too concerned about this system. I do think it is very telling that we are getting this development so early in the season. In fact, the long range models indicate several more tropical waves emerging from the African coast with decent development chances over the coming two weeks. If 95L does not amount to anything, I believe it’s only a matter of time that another strong tropical wave will and we could have a very active mid-July to deal with.

I’ll have another update here tomorrow morning.

M. Sudduth

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