[Update Update: The probability of ex-Isaac becoming a tropical cyclone is now 50%, and the storm is looking pretty good.]
[Update: The probability of this low pressure system turing into a tropical storm has been increased to 40%. It is moving in the general direction of some relatively warm water.]
Hurricane Isaac was supposed to move, as a tropical storm then as an extratropical low, up the Mississippi, then east across the middle of the US. However, the low pressure system that was once Isaac has instead started to move back south again, and it is now a low pressure system of interest. When I checked last night, there was a very small chance of this low forming a tropical storm, but this morning the probability of this happening is set at 20% (which is a very rough guess). There is a large low pressure system to ex-Isaac’s east which is expected to dissipate the energy of the erstwhile hurricane. But, so far, much of what has been “expected” for this storm has not happened exactly as planned. It would be interesting, not unprecedented but a rare event, if ex-Isaac moved back over the Gulf of Mexico, gained strength and got organized into a tropical storm then a hurricane.
Here is a picture of ex-Isaac at the present time, from the NWS Hurricane Center:
In case you were thinking that this has to be some other weather system not related to Isaac, I went to the archives and pulled the GEOS East Satellite images, one per day since mid week, and made them into a moving GIF for you: