Quiet tropics; update on Bill Proenza's doings

The tropical Atlantic is quiet today. The low pressure system over northern Florida that brought rain to the state Thursday has moved out to sea and weakened. Wind shear is high over this low, sea surface temperatures beneath it are cool, and I don't expect any development. None of the computer models are showing any tropical development over the next week. Our best chance of a new threat area to watch may not occur until the next strong cold front pushes off the U.S. East Coast. The long range GFS model forecast expects this to happen around Saturday June 30.

Bill Proenza news
In the absence of much to talk about in the tropics, we can always talk about the latest on new NHC director Bill Proenza. The View from the Surface blog is keeping up with the latest. Last night, I listened in to Proenza's comments on the Barometer Bob Show, an Internet radio show. I asked him where he got his numbers of 16% and 10% improvement for 72-hour and 49-hour hurricane track forecasts made using QuikSCAT satellite data (his boss, acting NWS director Mary Glackin, said "I'm not willing to stand by those numbers.") Proenza cited a study done of hurricane tracks from 2003 that showed these improvements, and Margie Kieper is working on getting a copy of this study for the View From the Surface blog. Margie came across a 2006 study which shows that for one storm studied (Hurricane Cindy of 1999), inclusion of QuikSCAT data improved track forecasts at 24 hours and 48 hours by 30-50% (Figure 1). There is also a 2007 study which showed improvements of 25%-50% for 24 hour - 48 hour model track forecasts of 2002's Hurricane Isidore using QuikSCAT data vs. no QuikSCAT data (Figure 2). We'll have more on the ongoing Bill Proenza hullaballo next week, with more info on just how important QuikSCAT is to hurricane forecasting.


Figure 1. Forecast error in the track of Hurricane Cindy (1999) with and without using QuikSCAT data. Image credit: NOAA. Data taken from the 2006 paper, The use of remotely sensed data and innovative modeling to improve hurricane prediction, by Robert Atlas, O. Reale, B-W. Shen, and S-J. Lin.


Figure 2. Forecast error in the track of Hurricane Isidore (2002) with and without using QuikSCAT data. Image credit: American Meteorological Society, "The Impact of Assimilating SSM/I and QuikSCAT Satellite Winds on Hurricane Isidore Simulations", by Shu-Hua Chen. Monthly Weather Review 135, issue 2, pp 549-566, February 2007.

Jeff Masters