Radar image showing the large amount of rain across portions of the Southeast
There is an awful lot of rain spreading across portions of the Southeast this morning but it’s not associated with the disturbance in the Gulf of Mexico – at least not directly.
Looking at satellite imagery, it is easy to tell that 92L has not become any better organized over night. The energy is not focusing around the weak low pressure center and continues to be spread out. As long as this continues, the system will not develop.
The pattern we’ve seen in place across the Southeast for the past several days will persist through the weekend with a change finally coming early next week. The front hung up across the area will fade and a return to a more typical summertime pattern will ensue. However, all of the rain that has fallen and that is still coming presents a problem to consider for later on: what if we get a tropical storm or hurricane landfall in this area over the next few weeks? I am concerned about the flood risk for the Southeast should a tropical cyclone pay a visit. So far, there’s not been any risk of that since Alberto back in June. We are coming up on the peak time of the season and there is a lot of talk in the hurricane forecasting world of a busy period coming up as the overall pattern seems to be heading towards one more conducive for development. We’ve seen a lot of rain across a good deal of the Southeast this summer. Rivers will be swollen and the ground saturated. Let’s hope this is not a set-up to a major flood event as we progress through the peak of the season.
In the east Atlantic, Erin remains a weak tropical storm as it fights the dry air still in place. This is not much of a surprise and I think it won’t be too much longer until we see the dry air ease up and the real meat of the season kicks in. In fact, another strong tropical wave is emerging from the coast of Africa now with potential for development over the next several days. At least for now, there are no threats for land areas to worry about.
I’ll post another update this evening concerning 92L and the rest of the tropics.
M. Sudduth 8:57am ET August 17
Vorticity chart showing the spin (red blob) associated with 92L in the Gulf of Mexico
A quick post about 92L this evening. As you can see by the 850mb vorticity map that I have included here, the system has the spin or vorticity that it needs to thrive. What’s lacking is organized deep convection wrapping around this spin. Without the convection wrapping around the center of circulation, which is clearly seen in satellite imagery, the low pressure area will remain fairly weak.
The shear values are not too strong but apparently are just strong enough to displace the main area of showers and thunderstorms off to the east and north of the center. Until and unless this shear lets up more, 92L won’t develop much despite sitting over very warm Gulf of Mexico water.
Computer guidance points towards Texas or northern Mexico but this is for the center. The worst weather, for now at least, is located well away from the center. It’s possible that Texas could see some beneficial rain from this system but how much and where is tough to say right now. The low should move steadily off to the west or west-northwest over the weekend.
We’ll see what the NHC says about this feature tonight and then see how it looks tomorrow morning. The Hurricane Hunters can get out there fairly quickly if need be should things look more interesting in the morning. For now, it’s something to watch but poses no major threat of impact over the weekend.
I’ll post more here in the morning.
M. Sudduth 4:35pm ET August 16
Model plots for 92L in the southwest Gulf of Mexico
There’s a lot to talk about this Friday so let’s get right to it.
First up, TS Erin continues to track WNW over the open waters of the east Atlantic but it is really beginning to struggle against the dry air. Add to this the fact that water temps where Erin is are marginal for supporting deep convection and the future of the storm does not look good. It won’t matter as Erin is forecast to move farther out in to the Atlantic, away from any land areas, and never be of concern.
Meanwhile, 92L has a small chance this weekend to become a tropical depression or weak tropical storm in the Gulf of Mexico. Upper level winds are not very supportive for development but, depending upon the track of the low, it could encounter an environment that would allow for some strengthening.
This system is complex and not typical of a potentially developing mid-August tropical system. Most of the heavy weather is located to the north and east of the center and is not wrapping around with distinct banding like we see in a more classic tropical storm structure. This should keep what ever strengthening that does manage to take place at a minimum.
Computer model guidance suggests a track towards the western Gulf of Mexico but I am not so sure that anything would be left to reach land. Most of the more advanced models break the system up over the next few days with minimal impact to land. Maybe we can get a little moisture to move over to Texas where they could use the rain – we will just have to wait and see.
ECMWF forecast for the MJO showing a very favorable pattern evolving over the next few weeks
The upcoming pattern looks very active as we head towards the end of the month and in to September. We have seen a very notable lack of upward motion or MJO activity in the Atlantic for the past several weeks. This has resulted in quite a bit of sinking, dry air across the tropics and we’ve seen the results of that with anemic tropical storms and no hurricanes forming. It looks like that will change in the coming weeks. The reason is the forecast for the MJO or Madden-Julian Oscillation which is looking more favorable for the Atlantic as we progress through the next several weeks. This should result in a dramatic uptick in activity across the Atlantic with the chance of seeing a hurricane develop as well. It will take a few more days for the pattern to evolve but the signs are pointing to a very busy end of the month and especially September.
I’ll post another update concerning 92L early this evening.
M. Sudduth 8:05am ET August 16