Hurricane Ida continues to move NNW in the Gulf, but already appears to be weakening a little since last evening. The satellite appearance is not as impressive as it was earlier. Below is a satellite loop from about 5 pm to midnight.

Air Force Hurricane Hunter Aircraft, in their latest report, indicated maximum flight level winds at 63 knots (72 mph), down from the 90-110 knot flight level winds they were finding yesterday and last night. The minimum central pressure has also apparently risen slightly.

As Ida continues to move northward, it will encounter cooler ocean water. A hurricane’s main intensity is due to low pressure caused by pulling in warm ocean water, and the humid air above it, high into the atmosphere. The warm, humid air is less dense than cold air, causing low pressure near the ground and strong winds. In this case, Ida is over water right now that is near 80 degrees, but it will be moving over water with temperatures in the 70s today as it moves into the northern Gulf. Some recent buoy/coastal reports indicate water temperatures of 70 at Pensacola, 73 off Orange Beach, and 77 100 miles south of Panama City. So, the cool water should cause Ida to weaken. Here is a map of sea surface temperatures in the Gulf.

Even 100 miles offshore, sea surface temperatures are below 26 C (79 F). Compare this to August 31, 2008, the day before Gustav hit Louisiana:

Then, water temperatures were 84 to 87 over most of the northern Gulf.

Ida will also encounter wind shear, and this tends to weaken hurricanes also. Upper-level winds at New Orleans tonight are 40 mph, not favorable for a significant hurricane.

All that being said, there are waves over 10 feet high only about 100 miles offshore, the storm only has about 24 hours to weaken before it hits land, and the strong winds today have built up a storm surge. So, it is still possible, though not likely, that some places along the immediate coast may experience hurricane-force winds (cat 1, about 75-80 mph) at times tonight and early Tuesday morning. This is one reason a hurricane warning is in effect, in addition to 4-6 foot storm surge. Widespread areas from SE LA into S MS through S AL and NW Florida will have several hours of winds gusting to 40-60 mph, with trees going down and power outages. Heavy rains will occur, some places getting over 8″. In general, though, unless something major changes today, this should not be a catastrophic event with severe property damage, like Ivan or Katrina. People in mobile homes and low-lying areas near the coast need to take precautions.

As far as effects on central Alabama… most models turn the storm sharply eastward toward south Georgia by Tuesday night. How much wind and rain we get in Birmingham will depend on how quickly the storm turns east. The consenus and NCEP indicate the heaviest rain will be from Pensacola to Auburn, with 4-5″. Some spots may get more. Here in the BHM area, it looks like rain will move in tonight, and we’ll get 1-3″ of rain before the rain ends on Wednesday, with higher amounts SE (Alex City, Anniston, Talladega) and lower amounts NW (Jasper, Tuscaloosa). It will become windy tonight and tomorrow, with winds gusting as high as 30 mph around Birmingham, and maybe over 40 mph south of Clanton.

UAH has a team with the MAX (Mobile Alabama X-band radar) on stabdby right now in Dothan, and we’re trying to figure out where is the best place to put them.