Onetime Tropical Storm Harvey, which died on Monday in the central Caribbean, is likely to come back to life stronger than ever and potentially slam into Texas on Friday. Extremely heavy rainfall may fall over parts of the Lone Star State.
The system, over the Yucatán Peninsula, is forecast to emerge in the Gulf of Mexico on Wednesday where very warm waters (86 to 88 degrees) could fuel rapid development.
— Brian McNoldy (@BMcNoldy) August 22, 2017
Computer model forecasts have gradually come into agreement on a scenario that puts the Texas coast at risk, and landfall is only three days away.
The National Hurricane Center sent out a message Tuesday afternoon advising people along the Texas coast to monitor the system, cautioning it could produce tidal and freshwater flooding as well as damaging winds if it comes ashore:
— Natl Hurricane Ctr (@NWSNHC) August 22, 2017
The latest run of the skillful European global model (ECMWF) predicts a strong tropical storm or hurricane will make landfall near the Texas-Mexico border area on Friday afternoon.
The European model is part of an overall model consensus that forecasts a strong tropical storm or hurricane to come ashore between Brownsville and Houston. We can expect tropical storm watches and possibly hurricane watches to be issued on Wednesday if the system regenerates as expected after leaving the Yucatan peninsula.
Even if Harvey does not reach hurricane intensity, the rainfall associated with it is still expected to be a big problem. Over coming week, large areas from the Mexico border over to the north-central Gulf coast could see very substantial rainfall totals.
Conservatively, at least a half foot of rain could fall in East Texas and even into parts of Louisiana.
It’s also possible that heavy rainfall from this system could even get drawn northeast toward the Tennessee Valley and East Coast in six to 10 days (some time next week).
If Harvey does end up becoming a hurricane, the threat of a damaging storm surge increases in addition to the threat of flooding from rainfall. Remember that the storm surge is the rise in water that occurs at the coast that can inundate normally dry land. Storm surge will be the worst immediately to the right or north of the landfall location and then possibly significant for hundreds of miles away.
The last August hurricane to hit Texas was Bret in 1999 and then Chantal in 1989. Since 1851, 17 hurricanes have made landfall on the Texas coast during August, so it’s actually not that common — happening on average about once per decade.
Another tropical system of interest near Florida
A disturbance approaching South Florida is a second area of interest in the tropics. We’ve been watching this one closely for well over a week, but it has been embedded in dry air so has been unable to develop.
It is forecast to stall over the Florida peninsula for the next four to five days and could unload pockets of very heavy rain, exceeding half a foot — especially in South Florida.
Sometime this weekend, it is expected to be picked up by the jet stream and head off to the northeast. The National Hurricane Center says the system has a 30 percent chance to develop into a tropical depression or storm in the next five days — which would most likely occur after it moves off the Florida peninsula over the ocean. If it does so, the next storm name on this year’s list is Irma, which is a new name introduced after Irene was retired in 2011.