Joaquin has continued its rapid intensification from tropical storm early Wednesday morning to major hurricane Thursday. As of Thursday afternoon at 2pm, maximum sustained winds were up to 130mph and a minimum central pressure was found at 936mb. Visible (as well as enhanced) satellite imagery shows a well-defined eye-feature surrounded by a fairly symmetric organization of deep convection. The eye is around 30 miles wide and is mostly closed, although the afternoon Air Force Hurricane Hunter aircraft found it to be open on the west-northwest side. The storm is moderately sized overall, with hurricane force winds extending 45 miles from the center and tropical storm force winds extending 140 miles outward. However, that wind field will likely expand in the coming days.
While the forecast remains uncertain beyond the next 48-72 hours, in the immediate Joaquin continues to pound the central Bahamas with long-duration hurricane conditions. With hurricane force winds continuing for such a long period (24-36 hours), wind damage is likely extensive for some of the islands in the central and southeast Bahamas. In addition, total rainfall amounts will likely be incredible, with some areas receiving up to 20″ by Friday afternoon. Finally, storm surge will be very dangerous. Across the northwest Bahamas, storm surge will be 2-4 feet but in the central Bahamas, water levels may rise 5-10 feet above normal tides. These pictures below are from Thursday morning in the central Bahamas (via the Bahamas Press) with more rain, storm surge, and wind damage to come.
Another risk for the Bahamas and eventually much of the eastern Seaboard will be surf and swells. The storm is already generating significant wave heights near 30′ and some models grow those heights to 40′+ later this weekend as the storm lifts northward. The combination of surf and rip-currents will likely cause life-threatening conditions on the east coast through the weekend and into early next week.
The storm continues to sit over extremely warm waters (85°+) and in an area of low wind shear. In fact, looking at the wind shear analysis via the University of Wisconsin, you can see the storm in an environment of wind shear less than 20kts. These factors should help the storm to strengthen some in the next 24 hours before the shear picks back up. However, since the storm is moving so slowly, it may be causing significant upwelling of the waters below it. This would cool down SST’s and ultimately cause some weakening but it remains to be seen just how much upwelling is underway. In addition, the storm’s intensity may fluctuate a bit in the next 24-48 hours due to an eyewall replacement cycle, which typically follows rapid intensification.
As for the track, the models shifted significantly Wednesday night and continue to do so Thursday. While the Euro was the ‘outlier’ for the last couple days, it now appears to be the lead dog. Many of the other dynamical and statistical models are jumping on board with an out to sea scenario. The spaghetti plots from Thursday afternoon’s runs continue to show this trend, with many model members far enough out to sea for minimal US impacts.
While the official track from the 11am update takes a middle of the road approach, the 5pm updated NHC track will likely be farther east given the continued trend east. The reasoning behind such a shift is complex but involves feedbacks at the upper levels of the atmosphere. While initially it was thought that a digging trough and upper level low over the Southeast United States would pull Joaquin back toward the coast, more models are jumping away from that theory. A stronger Joaquin would be less influenced by that trough and stay further out to sea.
Even if Joaquin stays offshore, it will likely still have significant impacts on the east coast. Moisture will be dragged into the Mid-Atlantic and Northeast with a stalled frontal boundary being the focus for ‘wringing out’ this moisture into heavy rain. The WPC total rainfall through early next weeks shows some areas picking up more than 12″ of rain! In addition, with high pressure to the north and low pressure (Joaquin) to the south and east, a long-duration easterly flow of gusty winds will likely pound the Mid-Atlantic and Northeast coastline. Besides the rip current and high swell risk, coastal and beach erosion is likely to be significant over the coming days. Stay tuned for more updates.