TROPICAL UPDATE: Tropical Wave (99L) Likely to Develop in the NW Caribbean threatens TX/ LA
UPDATE time for additional information about what is going on with topics and boy let me tell you something — it is getting extremely active and meteorologists are going to be working to the bone over the next 30 days. And what is even more ominous is that the upper air patterns in the western Atlantic Ocean and across North America show a pattern which is favorable for additional hurricane or tropical storm strikes in the Gulf of Mexico/ southeast US coast / and the Northeast US Coast. Of course there will be Tropical Cyclones (TC) that will turn out sea (in any given \year about 50% of all TC are essentially “fish storms”).
One of the things that really bother me with regard to making seasonal hurricane forecasts is this idea that you can make predictions regarding which areas of the coasts are more likely to be hit by TC activity. There are a lot of other meteorologists out there that love to make these LANDFALL predictions in the SEASONAL forecasts. WxRisk is a BIG believer in SEASONAL Hurricane forecasts. But this idea of pinpointing which areas in the Atlantic or Caribbean Basin are going to be favored for additional or enhance landfill activity in the March or June seasonal forecasts are pretty much worthless. To be sure, it is possible to see out one or two weeks by figuring out the large scale or synoptic weather pattern that are favorable for TC landfall impacts in a portion of the Atlantic, Gulf of Mexico, or western Caribbean coastal areas. But the principles of chaos theory and nonlinear Dynamics clearly show that it is not possible to do this beyond 30 days. Furthermore, research shows that the use of analogs of past hurricane seasons with similar atmospheric conditions to the current Hurricane season does not offer any value at all with respect to favored areas of enhanced tropical Cyclone activity.
This image shows the current satellite picture across the Atlantic Basin. Note that are three different tropical disturbances in this very active pattern. In case you don’t know tropical disturbances are designated in the Atlantic by a series of numbers from 91 to 99. And these numbers are used frequently throughout the hurricane season.
The tropical disturbance designated 97L came off the African Coast at fairly far north latitude a few days ago and is already turning to the Northwest. This system is close to becoming a tropical depression and it is likely to become a tropical storm shortly but it is also a fishing storm. It is to say it’s going to stay out in the sun to Atlantic Ocean and not be a problem for anybody.
Tropical disturbance 98L came off the African Coast on Monday and it is out of somewhat further to the south latitude. It clearly has cyclonic curvature and is clearly developing and has the potential to become a tropical depression or tropical cyclone in several days. If the system were to continue on a due west track and keep out of Philly far south latitude the threat of the system becoming a problem for either the Caribbean Basin the Bahamas were the Southeastern us would increase. This system will have to be watched over the next few days to ensure that it does stay on a West or West Northwest track. It is still possible that 98L could turn out to see it however.
The area of disturbed weather circled in red in the Bahamas appears to be a tropical disturbance which the Hurricane Center has not yet designated. They probably should do so as it does show some signs of development. At this time none of the global models or showing any sort of development with this system. With strong HIGH pressure in the western Atlantic Ocean it is likely that this system will move into Florida and/ or the southeast US coast during the next few days and provide enhanced shower and thunderstorm activity for the Southeastern US
The other threat, which is clearly the most impressive of the 3, is a tropical disturbance designated 99L. This feature is developing in the Caribbean basin which is a common breeding ground for tropical disturbance. It is becoming well-organized and WILL develop into tropical depressions. Indeed that is exactly what most of the models are \showing. The last several runs of the operational GFS and European models are developing 99L into a tropical cyclone and then potentially a serious hurricane for some portion of the Texas end or Louisiana coast.
This next image is an infrared satellite picture of what is going on in Africa and we can see 3 well developed large tropical LOWS — technically referred to as African Easterly Waves (AEW) that are marching across central and South Western Africa. Each of these systems appears to be ideally positioned to become tropical Cyclones in the future.
This image shows the European Tuesday afternoon ensemble plots at 120 hours / AUG 29. As you can see the three different tropical systems have moved on into various different directions. 97L has clearly turned to the north and northeast and is headed out to sea. The tropical system designated 98L has several different paths with some of the ensemble members turning the system to the north while other members show a track in a WNW direction towards the northern Leeward Islands. The system designated 99L is clearly developing and crossing the northern Yucatan and we’re moving into the Yucatan Channel.
At day 8/ 192 HRS valid September 1, we can see that the system in the northwest Caribbean 99L has become a significant TC and has made landfall somewhere on the Texas or Louisiana coast.. Both 97L and 98L have clearly turned to the N or NE and are now headed out to sea. But notice the cluster of LOWs just to the south of Cape Verde Island. This is likely to be one of those African LOW pressure areas mentioned above and is clearly going to develop.
The main focus next week is likely to be the system coming out of the western Caribbean and into or through the Yucatan Peninsula / channel (currently designated 99L). The early Tuesday morning weather models had the system as a strong Tropical Storm or weak hurricane making landfall across the Yucatan Peninsula then again along the Texas- Mexico border areas as a minimal hurricane. The European model early morning Tuesday British model had a track further up the coast closer to Central Texas and Corpus Christi.
However the midday and evening Tuesday August 25 model runs of the operational GFS showed a significant shift up the coast of Texas with this system and as a significantly stronger hurricane. The 12z Operational GFS also showed a landfall near Corpus Christi at 952mb a solid Category 3 hurricane. The 18z Tues op GFS showed a powerful 944mb hurricane striking the central Texas coast just south of Houston as a replay of IRMA !!
But the afternoon British model moved the system further back down the coast towards Brownsville.
If we assume for a second that 99L is going to develop then the key to this whole situation is where does it cut across the Yucatan Peninsula.? If the system were to completely bypass the northern tip of the Yucatan Peninsula that would strongly implied a landfall in Southeastern Texas or the Louisiana coast. If the system were to make landfall in central Yucatan it could still strike the central or Southern Texas coast but it would have a period of significant weakening as across the Yucatan Peninsula.
The key appears to be which piece of energy in the system designated 99L is going to be the main piece. If the northern piece of energy in the system becomes this main Center then it’s more likely to take a northern track which would increase the threat to the upper Texas and Louisiana coast. If the southern piece of energy becomes the main feature then it’s more likely to cut across the Yucatan Peninsula and then strike southern Texas or Northern Mexico.
DT/ WxRisk