[uncommonsense]

"But here you had a very slow moving system, with a massive wind field, and loads of potential for soaking rain."

I agree, wind speed is a big issue, but it isn't what kills most people. I've been in Boynton Beach FL taking care of my mother's affairs. Isaac sat over us for 3+ days dumping over 20" of rain. It was the slowest, largest pattern of storms I think I've ever seen (and I rode out Katrina / Rita in Baton Rouge).

I told my old friends back in BR to pay attention to the westward drift and the east side bands of torrential rains. That would be the most dangerous - from first hand experience over 3 days. My mother's place has great drainage and it couldn't keep up for the 1st time.

[thackney]

It was the slowest, largest pattern of storms I think I've ever seen

Tropical Storm (not even a Hurricane) Allison - Houston, Texas
2001

After making landfall near Galveston, Texas, on June 5, the storm moved inland to near Lufkin, Texas. Allison drifted back into the Gulf of Mexico on June 9, turned to the northeast, and made landfall again on June 10 near Morgan City, Louisiana. After causing 24 deaths in Texas and Louisiana, Allison moved across southern Mississippi, southern Alabama, southwest Georgia, and northern Florida, causing 9 more deaths. By mid-week, Allison stalled over North Carolina and produced more heavy rainfall and flooding before tracking northeast along the DelMarVa Peninsula and moving off the New England coast on June 18. Seven additional deaths occurred in Pennsylvania and one in Virginia.

Tropical Storm Allison caused more damage than any tropical storm in U.S. history, with estimates in excess of $5 billion. Most of the damage and fatalities (22) occurred in Houston, Texas. Storm rainfall totals peaked at 36.99 inches (Port of Houston) in Texas and 29.86 inches (Thibodaux) in Louisiana.

http://www.nws.noaa.gov/os/assessments/pdfs/allison.pdf