Intensifying Grace head toward Mexico and the Northeast has to keep an eye on Henri
Tropical Storm Grace is heading toward the Cancún/Cozumel resort area in Mexico and then into the Gulf of Mexico. The National Hurricane Center is forecasting that atmospheric conditions will allow the storm to reach hurricane strength before the outer bands reach Cancún tonight. The water in the northwestern Caribbean is as deep and warm as water anywhere in our part of the world, so Grace will pass over the equivalent of jet fuel for hurricanes.
The current forecast calls for Grace to be a strong Category 1 storm when it hits Mexico’s Yucatán Peninsula, but they need to prepare for at least a Category 2. The rule is to prepare for at least one category higher storm than forecast, given the intrinsic uncertainty in intensity forecasting.
The storm is expected to weaken when it passes over the landmass of the Yucatán, but the warm waters of the Gulf of Mexico are ahead. The current forecast calls for Grace to restrengthen into at least a Category 1 hurricane before it reaches the Mexican Gulf coast near or north of Veracruz.
What’s left of Fred is spreading rain to the north up the Appalachian Mountains and into the Northeast. The tropical airmass will reach the big cities of the Northeast tonight. Several inches of rain are forecast across the region, with the heaviest rain well away from the coast. Some tornadoes are possible across the Northeast and New England embedded in the nasty tropical weather.
Tropical Storm Henri is looping around Bermuda in the Atlantic. It is forecast to reach hurricane strength in the process. The only effect on land in the short term is on Bermuda. Winds near tropical-storm strength may impact the south side of the island.
As Henri pulls way to the north, the National Hurricane Center forecasts the top winds in Henri to reach hurricane strength. Henri’s most likely path is out to sea, but it’s not completely implausible that unusual steering currents could bend the storm back toward New York’s Long Island and the New England coast.
It appears that the track is related to how strong the storm can become. The long-range computer forecast models seem to show that if Henri becomes very strong, it is more likely to arc back toward the U.S. This appears to be an outlier solution at this point, but meteorologically speaking, not out of the realm of possibility.
This would happen fairly quickly – like this weekend. So everyone from coastal New York to New England should stay informed until we have full confidence that Henri will head out to sea.
In any case, Henri will generate high surf and dangerous currents along the East Coast.
On the other side of the ocean, a vigorous disturbance will move off the African coast tomorrow. The computer forecast models are predicting that the abundant Saharan dust over the east Atlantic will dry it out so it doesn’t become a factor, at least through the weekend. At this point it appears likely to turn north.