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Tropical Storm Isaias dies out as the tropics calm down

Aug. 5 model of the tropics.
Aug. 5 model of the tropics. (TropicalTidbits.com)

The remnants of Tropical Storm Isaias will die out in Canada today, swept up into a larger northern storm system. Thus will end the storm that took a close swipe at Florida, drowned Grand Bahama Island, hit North Carolina very hard, and has millions still without power in the Mid-Atlantic and Northeast today.

Isaias threaded its way between the Palm Beach County coast and Grand Bahama Island – a distance of about 70 miles. Occasional gusty squalls rotated over Florida, while much stronger winds and torrential rain pounded the Bahamas on the other side of the track.

When the storm was near Florida, upper-level winds blowing west to east combined with dry air left over from a Saharan Dust outbreak the previous week pushed the bad weather to the east side of the circulation, which meant the Bahamas got the worst of it.

As Isaias turned north toward North Carolina, the circulation was energized by warm Gulf Stream water and the upper winds that turned conducive for strengthening. The stronger system spawned a number of tornadoes as it was lifted north by an unusually energetic dip in the jet stream.

Winds Generated by Isaias.
Winds Generated by Isaias. (National Hurricane Center)

There have already been two tropical storms in the Northeast this year – Fay and now Isaias – and it is only the beginning of August. In addition, Cristobal hit the Gulf coast. It has been an unprecedented hurricane season so far in terms of Mother Nature’s tropical output.

On this depiction of the moisture in the middle levels of the atmosphere from the American computer forecast model, you can see Isaias’s moisture tail extending out of the circulation in Canada stretching across South Florida. That means the extra-humid weather will continue for another couple of days.

Elsewhere in the Atlantic, a small disturbance near Bermuda is struggling to survive in the dry air that has spread across the ocean from Africa to the US. It’s not likely to amount to anything.

Dry air is forecast to dominate the tropics into next week, which should keep the disturbances coming off of Africa far south and under control.


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