Tropics Quieting, No Threats on the Horizon
The tropics have significantly calmed over the past couple days. There is now just one active tropical cyclone in the world, Tropical Depression 8E in the East Pacific. As of the 5PM EDT advisory from the National Hurricane Center, 8E is located just over 200 miles WSW of Manzanillo, Mexico, and is moving west at 10mph. Maximum sustained winds of this system are estimated to be 35mph in accordance with satellite estimates. The minimum central pressure of the system is 1001mb. Tropical Depression 8E is actually the remnants of Hurricane Ernesto from the Atlantic. However, because the NHC said that Ernesto's circulation dissipated over Mexico, 8E will be renamed Hector, the next name on the East Pacific list, not Ernesto, if it gains tropical storm strength.
Forecast for 8E
The main inhibiting factor for intensification of 8E is wind shear. According to the latest run of the SHIPS intensity model, shear will remain between about 15 and 25 kts for the next 5 days. Ernesto is in a moist environment and over warm waters, so neither of these critical factors will hinder strengthening of 8E. The NHC is forecasting a peak intensity of 70mph in about three days before cooler waters begin to weaken the system. The intensity forecast is interesting because most intensity model guidance is showing very limited intensification, likely meaning they think the shear will prevent strengthening. However, I think the one thing that will help 8E to hold off the shear is its very large size. Generally, large systems are much more efficient at strengthening in a moderate shear environment than small, fragile ones. Therefore despite no intensity models forecasting this, I think Ernesto, like so many East Pac systems in recent years, will reach hurricane status and peak at around 90mph. This is a very low confidence forecast, however, as it is possible shear will prevent 8E from strengthening much above minimal tropical storm status.
Figure 1: Tropical Depression 8E.
There is also some uncertainty in the track forecast for 8E. The majority of models agree on a general west motion for the next couple days, possibly followed by a brief WSW turn as the NHC official forecast suggests. Several models then show the system bending back towards the NW. A couple of models, most notably the CMC, take 8E on a more northerly track towards Baja California. 8E is being steered by a strengthening ridge, so a general W motion should continue for a few days. However, since I am forecasting a stronger system than the NHC, I think 8E will weaken this ridge more than forecast and allow for a track a bit farther north than the official NHC forecast. I still do not anticipate 8E being a threat to land areas as cooler waters should weaken the system before it gets close to Baja California, if it goes that way.
Figure 2: Official NHC forecast track of 8E.
Also in the East Pacific, former Hurricane Gilma weakened to a remnant low today, as the NHC issued its last advisory on the system at 5PM EDT. Like so many East Pacific systems, it weakened due to cool sea surface temperatures and is now just a convectionless swirl.
Figure 3: The remnants of Gilma.
TD 7 Dissipates
In the Atlantic basin, Tropical Depression 7 dissipated today after a hurricane hunter mission this morning failed to find a closed circulation. This dissipation comes as little surprise as former TD 7 was in an area of unfavorable conditions and was never expected to strengthen much. As of their 2 PM Tropical Weather Outlook, the NHC is giving the remnants of TD 7 a 10% chance of redeveloping in the next 48 hours. I do not see any redevelopment of this system as it tracks through the Caribbean.
Figure 4: The remnants of TD 7, now an open wave.
93L Struggling, May Develop Later
In the far Eastern Atlantic, Invest 93L is struggling in the face of cool waters and dry air. As of the 2PM TWO, the NHC is giving 93L just a 10% chance of developing in the next 48 hours, a percentage I agree with. I still believe that development of this system is possible at some point in the next week as it moves into conditions that are a bit more conducive for development. If 93L were to develop, it should head out to sea without threatening any land areas.
Looking long range, the GFS continues to show development of multiple systems off Africa, but it has been very inconsistent lately so I do not anticipate much development in the next 1-2 weeks, and anything that does form should head out to sea.
Figure 5: The end of today's 12z GFS run, showing multiple systems. The model continues to indicate my prediction of a predominantly recurve pattern this month is on track.
Thank you for reading. Enjoy the rest of your weekend!