Immagine da satellite, con sovrapposta l'attività elettrica associata a Irma


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riguardo all'indebolimento, riporto quanto scrive Jeff Masters

Triple Trouble: Cat 5 Irma, Cat 3 Jose, Cat 1 Katia by Dr. Jeff Masters | Category 6 | Weather Underground

The Air Force hurricane hunter plane in the storm Thursday night found top surface winds near 165 mph on their first pass through the eye near 7:35 pm EDT, but only 140 mph on their second pass through near 9 pm EDT. The pressure stayed nearly constant in the two passes, at 920 and 921 mb, respectively. The reduction in the peak winds is not necessarily a good thing, since the hurricane hunter data showed that the hurricane-force winds of the storm had spread out over a larger area, which will increase the storm surge. In addtion, the fact that Irma maintained its very low pressure may mean the aircraft may have missed sampling the strongest winds of the hurricane.




Total precipitable water loops showed that part of Irma’s apparent weakening may be due to the island of Hispaniola blocking the inflow of moisture from the south, which was reducing the amount of moisture to the storm. This effect will diminish on Friday morning, when Irma moves to the west of Hispaniola. The hurricane will then be drawing air from the south over high terrain in Cuba, but the blocking effect of Cuba is much less than that of Hispaniola. I don't see any reason for Irma to weaken further through Saturday, and it may intensify again to 185 mph winds.