Ike Poised to Srengthen

Hurricane Ike moved into the Gulf of Mexico last night and has already begun to strengthen. Maximum winds are up to 85 mph along with a minimum central pressure of 959 mb. Satellite imagery suggests that the core of Ike was well established even after two landfalls in Cuba. In fact, Ike developed an eye again shortly after moving into the Gulf and continues to maintain its eye. Although Ike is not as symmetrical as it was last weekend, it has grown in size and will significantly improve its structure over the next 24-36 hours. Even still, it has a good banding presentation along with good outflow in all quadrants.


Where is Ike headed? After trending sharply to the left Monday and Tuesday, the computer models shifted back to the right yesterday and now are mostly clustered around the Corpus Christi area. Notable outliers include the GFS (South Texas) and UKMET (Freeport, TX). This year's reliable models the GFDL and European foresee a landfall near Corpus Christi or Indianola, TX. A strong ridge is forecast to build over Ike today. The main question at this point revolves around how quickly the ridge breaks down as a strong trough approaches from the west. This trough is currently located over the Western U.S. states and is amplifying the ridge downstream. This ridge will have major effects on the track and intensity of Ike. With respect to the track, this ridge should steer Ike generally on a WNW heading, and most models agree that the ridge should hold strong at least until landfall.

A few models do break down the ridge and turn Ike more NW prior to landfall. This would present a major threat to Galveston and the Houston area. Due to the uncertainty, residents from Brownsville to Galveston need to pay very close attention to Ike over the next couple of days. However, I feel that the ridge will remain strong through landfall, and I'm sticking with a landfall near Indianola, TX.


The intensity forecast for Ike is somewhat difficult as it always seems to be. There are currently two main impediments to prevent rapid intensification. Wind shear, the largest impediment, is a bit on the moderate side with 10-15 knots over the center, and this shear may be responsible for the asymmetric structure of Ike. Second, dry air does surround the hurricane, but it does not appear to be getting entrained into the center. As long as the dry air is not entrained, it can't really be considered a true impediment. While I don't feel that dry air will be a problem in the next 24-36 hours, the presence of the dry air can't be completely neglected. The wind shear, on the other hand, is strong enough to prevent a rapid intensification period in the short term. However, when the upper-level anticyclone builds over Ike later this evening, wind shear will drop off to less than 5 knots and expect Ike to intensify.



Ike will also be traversing the Loop Current and other clockwise loop eddies as it makes its way across the central Gulf. The Loop Current and eddies are extra sources of heat for the hurricane to ingest. One way you can think of it is that in a normal situation, the hurricane is just eating a steak from Applebee's. Sure, it's good but it's not top quality. When a hurricane passes over the Loop Current or a loop eddy, it's like eating a high grade Kansas City steak. This warm, deep reservoir of water and low wind shear will likely result in a rapid intensification period tomorrow. In fact, it should be no surprise if Ike is at least a Category 4 hurricane by tomorrow night.

The landfall intensity is a little more problematic due to the uncertainty of dry air, eye wall replacement cycles, and the approach of the trough. The one constant that will remain is the oceanic heat content will remain high, especially with a loop eddy just off the central Texas coast. However, dry air from the higher elevations of Mexico is always present, and it wouldn't take much to pull this dry air toward the hurricane. The approaching trough could also increase wind shear near Ike as it approaches the coast. I'm not banking on this scenario as much because I think the ridge will hold strong enough until landfall, but any increase in wind shear could disrupt the circulation and cause Ike to weaken. Lastly, the most difficult to forecast, eye wall replacement cycles dictate the strength of hurricanes. When a hurricane replaces its eye wall, it typically goes through a period of weakening. When the eye wall is replaced, the hurricane usually re-gains its strength quickly. Eye wall replacement cycles usually take ~6-12 hours to complete but can be as long as 24 hours.

If dry air is not a problem at landfall, Ike could certainly be a Category 4 hurricane. On the other hand, if dry air or wind shear are present at landfall, Ike will probably be a Category 3 hurricane. At this point, I think Ike will be a Category 4 hurricane with 135 mph winds at landfall. I may have another update later today.

For information on evacuations and other related news, check http://twitter.com/hurricaneike