Updated at 9 a.m. Eastern:
Tropical Storm Karl has a brief window of time to strengthen a bit before it runs aground in Mexico and hostile environmental conditions overtake it from the north. Hurricane Hunters flying into the system this morning found slightly higher winds but a poorly organized system. Instead of wrapping around the center of the storm, the thunderstorms are in a band on the east side.
Karl is trapped in the only corner of the Gulf of Mexico that could support a tropical system, and that somewhat conducive environment will shut down by Friday. Upper-level winds are already blowing across the system, pushing the strongest thunderstorm cells away from the center, but the winds aren’t yet strong enough to rip the storm apart.
Steering currents are very weak at the moment, so Karl is drifting around, but that will soon change. The shift in the weather pattern that will bring more hostile upper winds will also steer Karl south over the coast of Mexico into the extreme southwestern Gulf. The biggest danger from this storm will be up to a foot of rain over the higher elevations in southern Mexico.
Karl is currently forecast to arrive at the Gulf coast of southern Mexico on Friday.
The storm is disorganized and moving slowly, two of the factors that lead to less reliable and changeable forecasts. People in Mexico need to be aware that the forecast landfall point will likely shift over the next day or so until the steering currents are better established.
The change in the weather pattern over the Gulf of Mexico is really a change in the season. A cold front and associated winter-like dip in the jet stream will push down the Florida peninsula and across the Gulf at the end of the week. This first front won’t bring crisp air to South Florida, but it will be noticeably drier.
More importantly from a tropical standpoint, hostile upper winds are forecast to dominate the Gulf for the foreseeable future.
This doesn’t mean that tropical storms or even hurricanes can’t still form in the Caribbean or well out in the Atlantic, but it makes it less likely that anything more will threaten the U.S.
There have been occasional freak storms in late October and November, so we can’t 100% rule out another tropical system affecting the Gulf or East Coast, but the chances are low.