Trosum (tropical summary) -- Friday, August 31, 2012

By: Stu Ostro , 9:38 PM GMT on August 31, 2012

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Isaac poking northward into the strong, hot, dry ridge of high pressure which forced it west along the Gulf Coast and slowed its movement.

Image credit: UCAR


- Isaac's winds have continued to decrease and its rain pattern has become much more sporadic as its core moves away from the Gulf Coast. Nevertheless, it has been producing narrow bands of tropical downpours "training" over the same locations, such as in Pine Bluff, Arkansas, where significant flash flooding has occurred.

- While there will still be heavy showers scattered here and there to the south this weekend, as Isaac moves north and turns east rainfall will become more concentrated tonight and Saturday in the Mid-Mississippi Valley (Missouri, Illinois, southeast Iowa). Then during the remainder of the holiday weekend, Isaac's remnants will move across the Ohio Valley to the Appalachians.

- Isaac's ability to improve the overall drought situation will be quite limited; the exceptionally dry soil will be a limiting factor for flooding, however if too much falls too quickly that'd result in localized flash flooding.

- Although Isaac's wind energy is much lower than it was previously, it will continue to be sufficient for there to be a risk of very localized damaging wind gusts and short-lived tornadoes with the strongest showers and thunderstorms.


- Unlike Isaac, Tropical Storm Leslie will miss the Caribbean islands to the north. Steering currents will then become weak, though, and the storm won't move much next week.

- Thereafter, models are portraying the most likely scenario as one in which the core of Leslie stays east of New England; that's a long-range forecast and we'll need to keep an eye on future model trends. The ultimate track will depend on the strength/orientation of a dip in the jet stream predicted to develop over the United States and of a ridge of high pressure over the Atlantic north of the storm which will be slowing Leslie's movement.

- In any event, the track won't be too far from Bermuda, and the Canadian Maritimes stick out farther to the east than the U.S. East coast, so Leslie wouldn't have to be shoved as far west to put that region in play.

- With Leslie having a fairly large circulation which will churn up the Atlantic for days, ocean waves will reach the U.S. East Coast next week and cause an elevated risk of rip currents.


- By contrast, Kirk is tiny and headed even farther away from North America and Bermuda, but what's left of the hurricane will race to northwest Europe on Monday and could contribute some moisture and energy to the non-tropical system that will be absorbing it.


- Ileana, like many eastern Pacific hurricanes and tropical storms, will be moving over colder water, encountering more stable air, and weakening into a remnant low pressure system.

- The "monsoon trough" of low pressure offshore of Central America is active with a lot of thunderstorms, some of which are trying to consolidate and could become the next eastern Pacific tropical cyclone during the next few days.


- For the first time in a while, there are no tropical cyclones in the western Pacific.

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1. originalLT
1:18 AM GMT on September 01, 2012
Thanks for the run down of all the storms out there. Besides whats left with Isaac, I guess Leslie is the most interesting of the group.
Member Since: January 31, 2009 Posts: 0 Comments: 8011

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About stuostro

Senior meteorologist at The Weather Channel. Proud to be a weather-obsessed weather geek. Would be a DJ if not a meteorologist.

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