Remnants of TD 7 in the SW Gulf
Early morning satellite imagery shows that what was once TD 7 is coming back to life again in the southwest Gulf of Mexico. The NHC is indicating a 70% chance of it becoming a tropical depression again before it moves inland this weekend.
Computer models suggest a WNW to NE track towards Mexico as a tropical storm or category one hurricane (SHIPs model shows it reaching hurricane intensity). The overall circulation is fairly small and will only affect a limited area of the southwest to western Gulf and I do not see much impact for Texas. However, it is possible that some of the northern rain bands will move in to south Texas over the weekend. The main threat will be very heavy rains for Mexico with the possibility of a strengthening tropical storm at landfall. The NHC has tasked a recon plane to investigate the area later today if conditions warrant.
Meanwhile, we have a new area of interest just off the African coast that certainly bears watching. It has been designated as invest 94L and should steadily develop as it moves westward over the deep tropics.
All of the global computer models indicate that it will develop and it is likely to become a hurricane at some point since conditions are becoming more favorable along its path. This will be one to watch very closely as we move through the week next week. For now, it is in its early stages of development and we’ll just monitor how it develops over the weekend.
In the east Pacific, Hector has dissipated and there are no other areas of concern brewing in that region. I’ll post another blog here later this afternoon or early evening and will cover all of the goings on in the tropics thoroughly in the video blog to be posted in our app early this afternoon.
The east Pacific hurricane season has been quite busy so far with three named storms; one of them becoming a major hurricane.
It looks as though another tropical depression is forming not too far off the coast of Manzanillo. The good news here is two-fold. First, the system is only experiencing marginally favorable conditions to develop so it should not ramp up very quickly. Second, computer model guidance suggests that it will not track in to Mexico but rather turn back to the north and northwest over the next couple of days. While it could strengthen in to a tropical storm, none of the intensity models indicate a very strong system. Obviously, interests along the Pacific coast of Mexico will need to monitor this feature closely until it starts moving away.
Meanwhile, I am watching a large area of showers and thunderstorms that has developed over the southeast Gulf of Mexico and portions of the northern Caribbean Sea. The NHC mentions that there is a surface trough in the region which is simply a weak area of low pressure that acts like a focusing mechanism for unsettled weather. Upper level winds are not completely hostile but they’re not particularly favorable either. Water temps are plenty warm and this will lead to a continuation of the shower and thunderstorm activity that we currently have in place.
HPC Precip Forecast
Computer models indicate that the disturbance is likely to remain in the region and move slowly northwest throughout the remainder of the week. The result will be periods of stormy weather for the Florida peninsula. In fact, the precip forecast from the HPC shows the potential for several inches of rain to fall across south Florida (see graphic). Beyond that, I do not see much in the way of potential for the system to become a tropical storm although this scenario cannot be ruled out. As long as the disturbance remains disorganized and lacking of a well defined low level center, it will not do much more than be a large rain maker.
Elsewhere, invest 95L, over the cold waters of the North Atlantic, is a non-issue except for shipping interests. The storm system had some potential yesterday to develop in to a more tropical type storm but that window has since closed.
I’ll post another update here tomorrow with more info on the Pacific and Atlantic at that time.
Subsurface Temps of the Tropical Pacific
So far this winter, the La Niña that has been in place since last fall continues to hold strong. As the graphic from the Bureau of Meteorology in Australia indicates, subsurface temperatures across the tropical Pacific remain much colder than average over a large area. There is a growing region of subsurface warmth beginning to pool in the western Pacific but it lacks a real mechanism to drive it eastward- a so-called westerly wind burst. We typically don’t see those unless there is a significant pressure change across the Pacific and that shows up in the SOI or Southern Oscillation Index. When it is substantially negative, and persistently so, the trade winds often slow or even reverse, allowing the warm water gathering in the western Pacific to migrate eastward.
The latest update from the BOM also points out that long range climate models suggest a gradual warming of the tropical Pacific as the La Niña fades. This means it is likely that we’ll see a return to more average, or neutral ENSO conditions (ENSO stands for El Niño Southern Oscillation) by the time summer arrives in the Northern Hemisphere. There is also the possibility that the warming will continue and a weak El Niño could set in by next fall. I do not see any evidence yet to suggest that a strong El Niño is coming. However, this time of year, it is difficult to predict what will happen several months down the road but the large subsurface cold pool coupled with a fairly strong SOI signal over the past 30 to 90 days tells me that La Niña is going to be the rule for a few more months at least.
Why does any of this matter? Aside from the effects outside of the hurricane season, which are far too detailed to get in to in this post, we typically see a more active hurricane season when El Niño is not present. This is due to the stronger and more numerous instances of wind shear, the change of wind speed and/or direction with height, over the deep tropics. El Niño events promote this negative impact to tropical cyclones where as La Niña events usually do not.
For now, the La Niña pattern will continue but we’ll watch for signs that it is breaking down and then we’ll see how much warming takes place in the tropical Pacific. The end result could have an impact, one way or another, on the upcoming Atlantic hurricane season. I’ll post more about the ENSO state next month.