2013 East Pacific Hurricane Season Forecast
With March now more than halfway over, there is certainly already buzz over the upcoming Atlantic Hurricane Season. However, it's important to remember that the official start of the Atlantic season is always preceded by the official start of the other tropical basin close to the United States, the Eastern North Pacific, whose season climatologically begins on May 15. The East Pacific, on average, sees more tropical activity per season than the Atlantic, but usually sees less land impacts as well since the predominant direction of travel for tropical cyclones is west, taking them away from Mexico. Still, landfalls can happen in this basin, so it's important to keep an eye on. The East Pacific is heavily influenced by the same factors that influence the Atlantic: water temperatures, instability, shear, etc. Regarding ENSO, the effect in both basins is the opposite of the other; El Nino conditions, warm Pacific waters, tend to enhance East Pac activity while hindering Atlantic development, while La Nina conditions, cooler than average Pacific waters, tend to hinder Pacific development while promoting Atlantic development. This year, the effects in both basins are likely to be similar due to the fact that the ENSO will be so close to neutral- the effect of it will be that it doesn't really have an effect! Two factors that have been very persistent in one direction in the East Pac so far this year are shear and instability. Shear has been consistently higher than average, while instability has been consistently lower than average, as shown in Figures 1 and 2.
Figure 1: East Pacific shear graph, indicating shear has, for the most part, been well above normal (the black line) in the basin so far this year.
Figure 2: East Pacific instability graph, showing this year has been dominated by unusually low instability.
Neither factor just mentioned- the high shear and low instability- is good for development. In fact, it is just the opposite, as these things would tend to suppress development. With a lack of another anomalies, I think these two factors will be very important to keep an eye on. It is certainly possible that they could change as time goes on, as these are both factors that can change quite quickly. Still, with little else to base a forecast on, I am acting as if these factors will stay at least somewhat similar to where they are now. Because of that, I am forecasting near to below average tropical activity in the Eastern North Pacific. My numbers are as follows:
* 14 named storms
* 8 hurricanes
* 4 major hurricanes
Like the Atlantic, I favor these hurricanes to follow a standard climatological pattern in their time of development; I expect 0 May storms, 1 June storm, 2 July storms, 3 August storms, 5 September storms, 2 October storms, and 1 November storm. As always, potential impacts on land are all but impossible to predict, but logically I would tend to favor most storms running west, away from land. I do not foresee a major threat to Hawaii this season. I also do not think Baja California will be a target too much this year. One or two Mexican tropical storm landfalls is likely, with the possibility of a hurricane landfall at some point this season, likely during the peak months. I am hoping to provide fairly regular updates on the Atlantic and East Pacific in blogs this summer, and look forward to all the surprises in store.
Thank you as always for reading, and I hope you have a great second half of the week!