User blog:Hurricane Layten/Tropics getting busy as we end September

Just posting to say a few things on the current storms, and a few that are forecast to develop in subsequent days, but first, I think we will start with Typhoon Megi, which made landfall as a category 4 in the early hours of this morning, adding to their streak of powerful tropical cyclones this season. Typhoon Megi, which began its life as a tropical depression on September 21, has been able to work successfully with both the sea and air around it for the last several days as it has tracked generally north-westwards across the tropical Pacific Ocean. The typhoon is currently weakening over Taiwan, where extensive reports of heavy damages and flooding have already begun emerging in the hours since it made landfall with 130 mph winds. The JTWC seems bent on keeping it a strong typhoon until its landfall in China in the next 36-48 hours, before taking it into Vietnam as a slowly weakening system. The core of the system still looks impressive, with a vigorous central dense overcast still evident in the satellite imagery. I expect that Megi will follow its predecessors, Nepartak and Meranti, with similar impacts. Next up on the list is Tropical Storm Roslyn, which surprised the National Hurricane Center by continuing to intensify besides unfavourable upper level winds and decreasing sea surface temperatures, reaching its peak intensity at 50 mph in the early hours of this morning in the open Pacific well away from land. I expect that Roslyn will begin to weaken steadily, becoming a remnant low by early Thursday morning as it runs parallel to the Baja California Peninsula. Tropical Depression Nineteen-E, which developed at 1500 UTC yesterday continues to get better organised, and I expect that it will try and become a hurricane in the coming days as it drifts to the northwest, and then to the west towards the Big Island of Hawaii, where it should hit as an extratropical low in about 7 days’ time. Next up, and the storm that has had everyone’s attention since the GFS picked up on it almost 2 weeks ago – 97-L. the GFS continues to show a violent hurricane genesising in the Caribbean Sea, although it now seems to be taking it into Hispaniola as a category 4 hurricane, before heading out into the Bahamas and the US East Coast as a dangerous major hurricane. The HWRF has also been consistent, with taking the future Hurricane Matthew to category 4 as well before also taking it on a similar path to the GFS Full Res model. The only difference between the two models is that the GFS Full Res peaks Matthew as a strong category 4 off the East Coast, whereas the GFS takes the system out into the open Atlantic as a lower category 4. The CMC and ECMWF models have also seen a consistency of their own, with both models keeping the system as a category 2 hurricane in the Caribbean, before hitting western Hispaniola and heading out into the open Atlantic. The slower ECMWF model seems to be keeping Matthew on a more westward path, eventually taking the low out into the Gulf of Mexico near the Bahamas by day 10. The CMC on the other hand, takes Matthew out and up the East Coast as a highly dangerous major hurricane, letting the extratropical low make landfall in Nova Scotia as a very low pressured system with 90 mph winds. But we will have to see about which path the storm is going to take before it can be forecasted with any certainty. I expect that 97-L will become Tropical Depression Fourteen by 1500 UTC, and a tropical storm by this evening as it tracks through the Lesser Antilles, where no doubt there will be tropical storm watches and warnings issued for the passage of the system this evening and tomorrow morning. As I said yesterday, I wouldn’t be surprised, especially if Matthew tracks more westwards towards the Yucatan Channel, if it becomes a category 5 hurricane in the process. Anyone in the Caribbean needs to take this storm very seriously, as the forecast confidence will likely be very low once the storm forms, with the models constantly changing their outcome solutions between runs. Next up, but unlikely to do anything but be a nuisance to those along the coast of Campeche is a vigorous trough of low pressure that just seems to be sat over the dangerously warm waters in the Bay of Campeche. I wouldn’t be surprised to see this system rapidly organise into a tropical depression before landfall in Mexico in the next day or so, but the NHC says that upper level winds are too unfavourable for tropical cyclogenesis at this time, giving it a 10% chance of development before landfall. Either way, anyone in the path of this system needs to be closely monitoring its progress, because regardless of any development, this system will likely trigger life threatening flash flooding over the coming days whilst it is active. The CMC is also being very insistent that another tropical storm will form near Cabo Verde later this week as its precursor tropical wave moves towards the due west. However, as this tropical wave is forecast to once through the Saharan Air Layer, I doubt it will develop any time soon. However, once the Bahamas, there could be an opportunity for some organisation, providing the system can survive the hostile conditions that are ahead of it. If it does develop, its name will be Nicole, but we will have to see, because the CMC has the bad habit of suddenly changing its solutions form run to run. The remnants of Tropical Storm Lisa have also made it into the Tropical Weather Outlook this morning, though there is a virtually non-existent chance for it to regenerate as it moves towards the Azores in the coming day or so, where it should be absorbed by a larger non-tropical low to its northeast. Again, it is worth watching this system, because it does seem to be trying to organise, with some scattered convection well to the north and east of its exposed circulation. Top winds from an ASCAT A pass this morning were 40 mph, so anyone in the likely path of this system should be prepared for any possible impacts from the system in the coming day or so before it dissipates. Just one more thing. A new MJO phase is being forecast for the continental maritime regions in early October, so it may be worth the time to keep a close eye on any weather systems that develop or move into these regions, as they can often suddenly undergo tropical cyclogenesis with little or no warning. Ill post again tomorrow on the current situation.