Irene - First real hurricane threat of the season

As of Sunday afternoon, Tropical Storm Irene is located in the NE Caribbean, taking aim on Puerto Rico. The circulation is quite large, but so far intensification has been modest as it has been struggling somewhat with some mid-level dry air. The intensity forecast for Irene is going to prove very problematic as it complicated by several factors, but the main determining factor for Irene's intensity is interaction with land. The small NE Caribbean islands are not large enough to have a significant impact on Irene, but by tonight Irene will approach the larger island of Puerto Rico, and by Monday Irene will move very close to or directly over Hispanola. Not only is Hispanola much larger than the other islands, but much higher too. The highest elevations of the Dominican Republic, which comprises the Eastern 2/3rd of the island, exceed 10,000 feet. Higher, rougher terrain more effectively disrupts the circulation of a tropical cyclone. If Irene moves right over this mountainous area it will likely weaken considerably by then time it moves back over water. Then Irene must deal with Western Cuba, which is also quite mountainous. The graphic below shows the forecast cone overlayed on top of Cuba and Hispanola. Given the forecast error, Irene may or may not spend a considerable amount of time over land


Should Irene move along either Southern or Northern edge of the forecast cone, the weakening effect would be lessened, allowing for Irene to potentially become a formidable hurricane. A track straight down the center could disrupt the circulation to the point where Irene may struggle just to hold together. Such an uncertain intensity forecast makes the track forecast less certain too, as the movement of a tropical system system can be significantly affected by intensity. Everyone from the Eastern Gulf of Mexico to The Carolinas needs to pay attention to what happens over the next couple of days as it moves through The Caribbean.