Archive for November, 2009

My Latest Thoughts on Hurricane Ida

Posted in Severe weather with tags , , , , , , on November 8, 2009 by stormstream

My thoughts as of 10:30am EST on Sunday, November 8, 2009.

Wind will not be a huge problem at landfall, so whether Ida is a hurricane, strong tropical storm or is extratropical is only a classification concern, and not a sensible weather concern. There will be some storm surge issues, but nothing too terribly bad. Beach erosion should be moderate, but not severe. Overall, a system that should be a good one to sample from a high spot right at the coast if you are lucky enough to be able to get away and chase this one. One of the problems, however, with chasing Ida will be the time of landfall. I am projecting a landfall between 11pm Monday and 6am Tuesday. Nighttime landfalls are never much fun or photographically rewarding.

My official forecast is for a tropical storm in the process of transitioning to extratropical as it makes landfall near Mobile, AL at 3am CST on Tuesday, November 10. Maximum sustained winds of 70 mph, with gusts to 85 mph.

I said the wind will not be a huge concern at the coast, but that will not be the case inland. The gradient between the 1035mb high pressure over the Great lakes and the remnant low of Ida as it tracks across AL and GA on Tuesday will produce a swath of strong winds along and to the west and northwest of the low pressure center. These winds could easily be in the 30 to 40 mph range, with gusts to 50mph. The ground is still rather wet from the rains of late September and October, and additional heavy rain combined with these strong winds will provide the ingredients to bring down a lot of pine trees rooted in wet soil, and whose root systems have been compromised from years of prior drought. So, power outages and some property damage from falling trees appears to be a possible scenario from southern southern and central Alabama across central and northern GA and into the southern Appalachians of southeast TN, western NC and the upstate of SC. In fact, the higher elevations of the southern Appalachians could experience enhanced stronger wind gusts due to elevation.

Then we have the heavy rain element to contend with. Certainly enough rain is going to come down fast enough to create some serious flash flooding concerns. Like the wind threat, this will mainly reside along and to the west and north of the low pressure track across the Southeast. Once again, the higher elevations of the southern Appalachian mountains could take a serious hit from the heavy rain due to enhanced upslope rainfall. Hopefully the heavy rain will be quick hitting and not linger in any one given area for more than 10 consecutive hours, but there remain some questions with the models on just how quickly the heavy rain will move out, so this is certainly something to watch closely. Also, leaves are falling and the wind and rain will shake a lot more off the trees. These will choke drains and create serious road flooding issues.