Cyclone Gino Likely to Strengthen, No Threat to Land
As we move through the heart of winter in the US, we continue to move through the heart of Southern Hemisphere cyclone season. The past couple weeks have been fairly quiet in the South Pacific and South Indian basins, but we now have a system to track in the South Indian. This is Cyclone Gino, a system currently located over the open ocean about 630 nautical miles ESE of Diego Garcia, according to the latest warning from the Joint Typhoon Warning Center. The JTWC is estimating the system's maximum 1 minute sustained winds as being 45kts, the equivalent of a weak/moderate tropical storm in the Atlantic. This intensity is based off of a variety of Dvorak estimates, particularly ADT estimates which had been running in the 45-50kt range at the time of the advisory, and have continued to climb since then. Gino is moving SW at approximately 9kts.
Figure 1: Cyclone Gino, showing the system's improving outflow pattern.
Forecast for Gino
Cyclone Gino is under the influence of a large subtropical ridge, which it is on the northwestern edge of. Because of this, a continued SW motion is expected for the next day or so. After this time, however, a potent shortwave trough is expected to weaken this steering ridge, causing Gino to turn more to the SSW, then S, and eventually SE. In the South Indian basin, this is basically the equivalent of a recurvature in the Atlantic. Favorable atmospheric conditions and warm waters will cause Gino to continue to intensify for the next 2-3 days. The JTWC is forecasting a peak intensity of 85-90kts in just over two days. The main limiting factor for the storm to intensify further is lack of time, as after about 60 hours the storm will begin to encounter strengthening vertical wind shear and gradually cooler waters which will become less conducive for supporting a tropical cyclone. Extratropical transition may begin as early as 72 hours from now, and the JTWC forecasts the storm to be fully extratropical in 4 days. I am in general agreement with their peak intensity forecast, though I would lean towards a slightly stronger storm, possibly up to 95kts. I also expect the storm to survive a little longer than JTWC, likely not completing extratropical transition for about 5 days. Gino will be traversing the wide open ocean, so it will not provide any effects to land.
Figure 2: Official JTWC forecast track of Gino.
After just a brief life as a tropical cyclone, Cyclone Haley in the South Pacific has dissipated well SSE of Bora Bora in French Polynesia. Dry air, high shear, and cooler waters caused all deep convection to remove itself from a now elongated center. This system will not be a threat for regeneration.
Figure 3: The remnants of Haley.
There are no other disturbances currently being watched for development right now. Models have been inconsistently showing various areas of development in both the South Pacific and South Indian, but it seems too spotty to take seriously right now. There is also the possibility of West Pacific development within the next week to 10 days, but again, there is not enough model consistency to take this seriously yet.
Thank you for reading, and have a great week! I will likely post an initial 2013 Atlantic Hurricane Season forecast at the end of this month or sometime next month, with possibly some other entries about the global tropics if necessary over the next few weeks.