While Karl struggled with strong vertical wind shear for a little longer than expected, and weakened into a tropical depression, Karl has since moved into a region with lower vertical wind shear. The upper level low that had been trailing Karl and keeping strong, shearing upper-level winds over the storm has continued moving off to the west while Karl has begun to turn to the northwest.
This diminishing vertical wind shear across Karl is allowing the deep convection to organize near the center of the cyclone. Further, sufficient sea surface temperatures of ~29°C/84°F and a more moist environment are helping Karl sustain this deep convection. These factors support Karl strengthening steadily on its approach to Bermuda. Aircraft observation have indicated that Karl has continued to strengthen overnight with the minimum central pressures falling at a rate of 9 mb between 9pm last night and 9am this morning, a sign that Karl has begun this strengthening, and could strengthen more quickly today as its environment continues to improve. Karl could strengthen into a hurricane before passing Bermuda and additional warnings might be necessary later today.
Karl is expected to continue tracking to the northwest this morning, turning more to the north this afternoon, and north-northeast this evening/overnight. The 9am forecast track from the National Hurricane Center takes Karl about 50 nm to the southeast of Bermuda.
On this forecast track, Bermuda can expect strengthening easterly winds today, winds then back to the northeast and north this evening and overnight and peak as Karl passes to the southeast. Tomorrow morning, winds continue backing to the north and northwest and begin to subside. Northwesterly winds continue to diminish through the day on Saturday.
Steady, at times heavy, rain is expected to begin this afternoon, with isolated to scattered showers possible late this morning. Embedded squally showers are possible as early as this evening through overnight with a small but non-negligible chance for tornadoes.
Peak winds on island are expected to be strong tropical storm strength with gusts to hurricane strength, particularly in areas exposed to northwesterly, clockwise through to easterly winds. Small deviations in Karl’s heading (ie. wobbles) and therefore track could result in very different conditions felt on Bermuda. For instance it is possible that Karl track directly overhead of Bermuda or to the west of Bermuda, in these scenarios, wind directions would be different or even opposite, exposing a different set of hillsides to the strongest winds and gusts.