Average 20 year old weather nerd. Sophomore @ Plymouth State University, majoring in meteorology, with the goal of becoming a professional forecaster
By: MAweatherboy1 , 11:35 PM GMT on May 14, 2013
Happy East Pacific Hurricane Season! Indeed, in just hours, the first official tropical weather outlook for the Eastern North Pacific basin will be issued by the National Hurricane Center, officially beginning the season which runs from May 15-Nov 30. The East Pacific couldn't quite wait for the start of its season, however, as yesterday the first invest of the season, 90E, formed. This is certainly an exciting moment, as it is a strong sign that Atlantic Hurricane Season is also soon to be upon us. Invest 90E is currently located about 650 miles south of Acapulco, Mexico, and is drifting WNW, away from land, at 10-15mph. This general motion should continue for at least the next 3 days.
Figure 1: Invest 90E.
Satellite imagery reveals that 90E is a very typical, slowly organizing East Pacific invest. It has managed to establish itself as a separate entity from the intertropical convergence zone, which is always an early and important step in determining whether or not an invest will develop. The system has also managed to maintain convection for an extended period of time, and while the convection overall is not quite as strong as it was yesterday, it is definitely better organized, as 90E looks much more like a tropical system now than it did 24 hours ago. The latest (18z) update from the ATCF indicates that 90E is estimate to have maximum winds of close to 30mph and a minimum pressure of 1007mb. As of their 12:45 PM PDT Special Tropical Weather Outlook, the National Hurricane Center is giving 90E a 30% chance of developing within the next 48 hours. 90E is in an environment that is generally conducive to organization, with the SHIPS intensity model showing 90E traveling through less than 10kts of shear for the next three days, and a moist enough atmosphere for development. I am giving 90E a 40% chance of developing into a tropical cyclone within 48 hours, and a 70% chance within 96 hours. The GFS, CMC, and NAVGEM models all show some sort of development of 90E within 72 hours, while the ECMWF model, generally considered the world's best major global model, does not show development. This can likely be attributed to the glaring weakness of this model, which is forecasting tropical cyclogenesis. Because of the tendency of this model to not accurately capture development (such as for Cyclone Mahasen in the Bay of Bengal) I have mostly discounted its solution, as I believe 90E will develop into the East Pacific's first tropical depression, and possibly tropical storm, of the year. Should 90E strengthen to tropical storm status, it will be given the name "Alvin." My forecast for the system is below. This is meant to cover a period of about 5 days at a steady speed. The track forecast is based off a blend of the more northerly/easterly GFS, which never gets the system to 120W, and the more southerly/westerly CMC and NAVGEM, which do bring it to and past 120W. Intensity is less aggressive than models like the SHIPS (which brings 90E to 60kts in 72 hours) and GFS, but more aggressive than the NAVGEM and obviously the ECMWF which doesn't show development. I think this will become the basin's first named storm of the year.
Figure 2: My forecast track and intensity for 90E, not official. Map credit.
As always with invest forecasts, there is considerable uncertainty in both track and intensity, and future changes are a good bet. Still, there is no reasonable scenario that would have 90E impacting land in any way, as it should be a threat solely to marine interests, as most East Pacific storms are.
Figure 3: Recent visible image of 90E.
I hope to provide updates on 90E in the days ahead, and as I have mentioned in previous blogs I hope to provide fairly regular blog updates on Atlantic and East Pacific systems this year, though that will be tough for the next month or so as school finishes up for the year.
Thank you for reading, and I hope you enjoy the rest of your week.
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