First and foremost, listen to the National Hurricane Center’s forecasters and your local weather service office and local emergency officials. The intent of this post is to inform you of the extreme potential of Hurricane Ida. This is not a forecast. This is a warning that Ida is already intensifying more rapidly than forecast and that indicates when Ida tracks over the Loop Current after passing over Cuba that all hell could break lose. Models showed that there was moderate shear south of Cuba that should have slowed Ida’s development, but Ida developed rapidly despite the shear. That’s a very bad sign because the shear is forecast to weaken over the Gulf of Mexico to light shear.
The hurricane center was predicting Ida to be a major hurricane with winds of about 120mph (105kts) at landfall, but they just upgraded the forecast to 140mph (120kts) at 5pm EDT. Several models that tend to forecast on the high side now show that Ida will be a category 5 storm at landfall. Those models should be used as evidence that the potential is there for Ida to be an absolutely devastating storm, with the understanding that their intensity forecasts are not reliable.
This morning as the Air Force hurricane hunter plane passed through the center of Ida the central pressure dropped 10mb from the first pass to the fourth pass. That’s a rapid pressure drop.
At 2pm eastern time the NHC upgraded Ida to a hurricane as it passed over Cuba’s Isle of Youth.
9pm EDT Update: Radar eye is staying intact while passing over Cuba
The passage over Cuba does not appear to be disrupting Ida’s structure on radar. Strong organized convection has developed over the Gulf of Mexico north of Cuba. This can be seen well from two Cuban radar sites one east and one west of Ida. Ida is now entering the Gulf of Mexico in favorable condition for intensification over the deep warm waters of the Loop Current.
End 9pm EDT update.
For an excellent technical presentation that will tell you everything you wanted to know but didn’t know how to ask, watch hurricane and typhoon forecaster Levi Cowan’s youtube video from this morning. Levi started as a young prodigy, got his PhD studying hurricanes, and now works at the Joint Typhoon Warning Center. He knows his stuff. Ida has become stronger and better organized in the few hours that have passed from when he made the video.
Since Levi made the video, Ida’s radar signature became much more symmetric indicating the beginning of the process of eye formation. Passage over Cuba will likely disrupt that process, but the passage will be quick. Ida could begin rapidly intensifying soon after passing over Cuba. The sooner the intensification process gets started, the stronger Ida could be at landfall. The main thing holding Ida’s potential intensity at landfall down is the time it will take to intensify.
Cuban Radar loop showing Ida becoming a hurricane near the Isle of Youth
The problem for residents of the central Gulf Coast is that there is a very short evacuation window. Residents need to plan for the worst, a category 5 near them while hoping for the best. Conditions will begin to degrade Sunday morning before the expected landfall Sunday night. There may be no way to evacuate on Sunday if the storm is stronger than presently forecast by the NHC. The HMON and HWRF models both show Ida approaching the central Louisiana coast as a category 5 hurricane. The HWRF model is notorious for forecasting intensities that are higher than realized, but when the HWRF and HMON agree on very high intensities, they often get it right.
Please, everyone in the potentially affected area, go to safety. Follow evacuation orders, but even better, get out ahead of the crowd before the orders are given. This one looks deadly. In the middle of the pandemic you want to get out early. The combination of Delta and Ida will be devastating.
ROC’s diary with list of local resources in Louisiana is here: www.dailykos.com/...