Tropical Storm Cristobal is straddling the coast of Mexico in the extreme southern Gulf of Mexico. Torrential, life-threatening rain continues to fall on the southern part of that country. Two to three feet of total rainfall is forecast over a wide area.
The tropical storm has been embedded in a larger, rotating system – an area of low pressure called the Central American Gyre – which is causing it to make a slow loop. Since there are no steering currents strong enough to break up the gyre and move Cristobal along, it is expected to move very little for the next day or two.
The atmospheric conditions are conducive for strengthening, which has resulted in Cristobal becoming a fairly strong tropical storm. The big question is, how much will the system interact with land? Some computer forecast models essentially kill off Cristobal as it drifts over southern Mexico, others just wound it, and move the center back over the Gulf allowing the tropical system to stay intact.
In either case, beginning Thursday night, a strong dip in the jet stream will provide a path to the north for whatever remains of Cristobal and the large area of moisture associated with the gyre. Because the slightest difference in the track makes so much difference in what gets pulled north, we have to consider a range of possibilities.
At this time, it appears that the bulk of the wind and the rain will stay away from southeast Florida. If the system moving north is weak, however, the moisture would likely spread out more and have more effect on the peninsula. If the storm is strong, the circulation will likely consolidate the moisture closer to the center and Florida will be drier.
We have to wait to see how much of Cristobal remains late tomorrow.
If Cristobal survives with a viable circulation, it would likely move toward the northern Gulf coast over the weekend with a large envelope of moisture as at least a moderate storm. Most of the rain and wind would avoid Florida in that case. But if it ends up being a weaker system – an unwound spring, so to speak – the moisture would spread out across Florida. In this case, more significant rainfall over the peninsula would result, which could last into next week.
In either case, heavy rain will overspread the northern Gulf coast ahead of the storm. The most significant effects from Cristobal or whatever moves north will be to the right of the track, so don’t concentrate on where the center of the storm is forecast to be.
We don’t know exactly what will happen at this point, but this is guaranteed to be a lopsided storm with the bad weather well to the east and ahead of the center.