Average 20 year old weather nerd. Sophomore @ Plymouth State University, majoring in meteorology, with the goal of becoming a professional forecaster
By: MAweatherboy1 , 12:51 AM GMT on October 07, 2012
Believe it or not, there is plenty of action in the tropics right now, as I am watching six separate features scattered all over the world tonight.
Tropical Storm Olivia Forms
After coming together quite quickly yesterday and continuing to organize this morning, Invest 96E was declared Tropical Depression 15E at 11AM today, and after continued organization during the afternoon, it was upgraded to Tropical Storm Olivia at 5PM EDT today. As of the 5PM advisory, Olivia's maximum 1 minute sustained winds are estimated at 45mph, with a minimum central pressure of 1004mb. She is located well offshore of Mexico, about 900 miles SW of Baja California, and is moving west, further away from the coast, at 12mph.
Forecast for Olivia
The official NHC forecast takes Olivia to 65mph in about 36 hours. This is very similar to what I predicted last night, and it still seems reasonable to me. It appears the rather quick consolidation seen earlier in the day with the system has stopped, and the gradual strengthening indicated by the initial forecast through 36 hours should be on track. After this time steady weakening is likely as strong shear, dry air, and cooler waters begin to impact the system. The track forecast is fairly straightforward as it is currently being steered westward by a weakening ridge. This ridge should continue to weaken, causing a turn more to the WNW/NW shortly, followed by a bend back W or even WSW later in the forecast period as the circulation becomes weak and shallow and susceptible to being moved by nothing more than trade winds. My forecast would indicate a more northerly solution as I think the ridge will break down enough to cause a solid NW turn as opposed to a more WNW solution shown by the NHC. Regardless, Olivia will never be a threat to land.
Figure 1: Tropical Storm Olivia.
Figure 2: Official NHC forecast for Olivia.
Invest 97L Unlikely to Develop
An area of disturbed weather persisted a couple hundred miles east of the Bahamas this morning and was designated Invest 97L. As of their latest (8PM EDT) Tropical Weather Outlook, the NHC is giving 97L a 10% chance of development in the next 48 hours. 97L is in an area of unfavorable conditions, with shear being the biggest issue, and I do not believe this system will develop as I give it a near 0% chance of development in the net 48 hours. Regardless of development, increased shower and thunderstorm activity is likely in the eastern Bahamas for the next couple days.
Figure 3: Invest 97L. The system is struggling, and there has been a significant decrease in deep convection in the past several hours.
Invest 90S Will Not Develop
We had a somewhat interesting event occur a couple days ago as the Southern Hemisphere's first invest of the season, 90S, was born. It looked decent at times over the past couple days but is currently dissipating and will not develop. Still, this is definitely a sign that times are changing, as the Atlantic's season winds down.
Figure 4: Invest 90S this morning. The clockwise circulation is evident, as opposed to the counterclockwise circulation Northern Hemisphere storms display.
Gaemi May Attempt to Regenerate
In the West Pacific, Tropical Storm Gaemi was declared dissipated earlier today by the Joint Typhoon Warning Center after making landfall in Vietnam. I have not heard of any significant damage out of the area, though their were worries that heavy rains could damage the coffee crop. While it is now just a remnant low crossing over southeast Asia, Gaemi may not be done quite yet. The GFS is indicating what's left of Gaemi emerging over the Bay of Bengal in about 2 days. Some runs have shown the remnants attempting to redevelop, and today's 18z run actually showed the most significant redevelopment yet. Because Gaemi is such a weak circulation, however, I am not ready to buy this yet, as I think it is more likely the remnant low will dissipate over land or become too disorganized to redevelop when it emerges over water.
Figure 5: The remnants of Gaemi.
93B Unlikely to Develop
Sticking with the Bay of Bengal theme, the first invest in quite a while has formed in the Bay, invest 93B. 93B is currently weak and disorganized, and it does not have much time over water to develop, and none of the major global models show development of the disturbance. The JTWC has not mentioned 93B on its Indian Ocean tropical weather outlook.
Figure 6: Invest 93B.
99W Could Become A Powerful Typhoon
The final stop on our worldwide tour tonight is in the open waters of the West Pacific, Invest 99W. This disturbance has been tracked for several days, and the JTWC currently has a Tropical Cyclone Formation Alert issued for it, meaning there is a high chance it will develop into a tropical cyclone in the next 24 hours. Its current satellite appearance is fairly impressive for an invest, and advisories could be initiated by JTWC at any time. Steady organization is likely for the next 4 days, as indicated by the GFS and ECMWF models. After this time these same models indicate the potential for more rapid strengthening as conditions will be very conducive for development. I don't foresee this becoming a Cat 5 monster like Sanba or Jelawat, but a Cat 3 is definitely within the realm of possibility. Regarding track, 99W should follow a typical pattern of a recurving West Pacific storm. The question will be how close will the system get to Japan? As of right now most indications are it will pass south/east of the country in 8-10 days, but we will have a much better idea of the exact track in a couple days when models have a more well defined system to track.
Figure 7: Invest 99W, which is likely nearing tropical depression status.
Still Watching the Caribbean Long Range
As I mentioned last night, the GFS was showing tropical development in the Caribbean in the longer range. The GFS runs today have been rather unenthusiastic about development, but we see models flip flop like this all the time, and with the MJO returning and climatology favoring the Caribbean at this time of year, it's still possible we could be dealing with something in two weeks or so.
Thank you for reading, and enjoy the rest of your weekend!
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