North Atlantic is Warmer, More SEP/OCT Hurricanes

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Busy North Atlantic Tropics
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The North Atlantic basin tropics have warmed substantially according to NOAA/NHC analysis. Coupled with no El Nino the mid-to-late tropical cyclone season across the North Atlantic basin should produce 5-7 hurricanes - more than previously forecast.

Number of hurricanes forecast for remainder of season increases

Discussion: Based on the weekly SSTA analysis provided by NOAA/NHC a dramatic warm-up of the North Atlantic basin is underway. Surface water east of the Northeast U.S. Corridor has been warm and is now possibly record warm. The warm SSTA east of the Northeast U.S. Corridor assures a warm autumn ahead. The Gulf of Mexico continues warmer than normal. The large change is the warm-up of the tropical North Atlantic previously cooler than normal.

Meanwhile in the East Pacific equatorial region the SSTA have cooled especially the farther eastern sector. Forecasts for El Nino onset are delayed until late this year therefore the remainder of tropical cyclone is not expected to gain the upper westerly shear defeating North Atlantic tropical cyclones.

Given the warmer tropical surface in the outer North Atlantic tropics and no El Nino the number of hurricanes likely to occur in September and October in the North Atlantic is at least near to slightly above normal. The normal number of hurricanes is September is 4 while October averages 1.5. The next 8 weeks should produce at least 5 to as many as 7 hurricanes.

Fig. 1: Weekly North Atlantic SSTA analysis provided by NOAA/NHC.

Fig. 2: Weekly East Pacific SSTA analysis provided by NOAA/NHC.

Fig. 3: the Nino SSTA regions remain in neutral phase. No El Nino yet in the East Pacific.