Tuesday, August 06, 2013

One Hurricane Forecast Nudges "Sorta" Lower

Philip Klotzbach and William Gray's tropical cyclone forecasts are often among the more anticipated ones (if there is such a thing) in the weather community given Gray's relatively well-known status for long range forecasting on tropical cyclones and the contributions he's made in developing parameters that are now commonly used in many other forecasts.

The tandem recently updated their forecast for the 2013 hurricane season, with an ever-so-slight reduction in the level of intensity of the projected season expected over the remaining months.

Their initial season forecast called for 18 total named storms, of which nine would become hurricanes and four reach Cat 3 status (aka major hurricanes) on the Saffir-Simpson scale.  Their update knocks one hurricane and one Category 3 or greater off of the total (18/8/3 vs. 18/9/4).

Click on graphic to see at full size. Via Colorado State University.

Their forecast still suggests a slightly higher risk for a major hurricane to strike the East Coast compared to the average risk of the past century, partly due to us being in an active period historically (more storms compared to pre-1995 levels and thereby a higher risk for any one of them to landfall) and partly also to the predominate pattern aloft. They have nudged the hurricane projection lower by one as slightly cooler oceanic temperatures across eastern portions of the tropical Atlantic earlier in the season, plus a more stable atmosphere (thank you dry, dusty air chugging west through the Atlantic now) are helping put a bit of a lid on the potential for tropical development overall.

Granted, the lower nudge isn't a big change...it's not like they're canceling hurricane season or anything of the sort. That said, the season isn't progressing at as fast a clip as last year (our "D" storm last year developed a month earlier than this year) but with the core of the tropical season ahead of us, numbers can quickly rack up if conditions become more favorable in the tropical Atlantic (the Saharan Air layer fizzles, for instance, and allows more development in the Cape Verde belt).