Naturally, about 20 minutes after my scolding this morning, and only an hour and half since their last update, the National Hurricane Center decided to upgrade Isaac to a hurricane. In the bigger scheme of things, it really doesn’t matter. From 70 to 75 miles per hour is not that big of a difference and it won’t really affect the area that much differently. It’s more the principle and how every else in the scientific community views these storms with a standard of measurements, but I digress. Hurricane Isaac is still heading towards the mouth of the Mississippi River at about 10 miles per hour and is currently about 50 miles from the coast. Satellite data shows that Isaac could be slowing down a little more as it gets closer to land. This will mean two things. It provides the storm a little extra time over water, up to 12 hours or so, to use the warm Gulf water and “frictionless” surface to continue to intensify. Although it’s not likely to make it to a major hurricane, it is conceivable, combined with the low pressure, that Isaac could strengthen to a category 2 storm. I would give that likelihood about 30% right now. The second thing will be the extra time allowing the rand bands to cross over the same areas, over and over again. This is what will make Isaac more deadly than the strong winds: consistent, unrelenting, heavy rainfall. Numerous areas along the Gulf coast are already reporting road closures from flooding and storm surge, especially from Gulfport, MS over to Mobile Bay. Rainfall accumulation forecasts from this morning indicate the target for the highest rainfall amounts will be around the Bay of St. Louis to Biloxi, MS, where totals could approach 20 inches.
Although they are not particularly large with tropical systems, tornadoes are another threat with hurricanes and tropical storms. Most are EF0 or 1 and generally do not last very long, but they can still throw a tree into your home. I have already seen tornado warnings for some of the outer rain bands that have come ashore. If you decided to stay home, I’ll state the obvious, all of your preparations should have been made and completed. Make sure you have a radio or some device to be able to listen to weather reports and stay up to date on the latest conditions. Unfortunately, this storm will hang around for a while, perhaps even until Thursday morning, before things start to improve. So hunker down, enjoy a board game and stay safe.
I’ll try to give another update later tonight around or just before landfall and if any additional developments in strength arise.