The National Hurricane Center is writing advisories on Tropical Storm Boris currently centered just off the Pacific coast of Mexico not far from the Gulf of Tehuantepec.
The forecast is for it to move slowly northward and weaken over the mountains of Mexico.
Although the region of Mexico near the Isthmus of Tehuantepec is relatively narrow, it is very unlikely that an identifiable center of circulation will be tracked all the way into the Gulf of Mexico due to the mountainous terrain and the slow movement of Boris.
--Satellite image of Tropical Storm Boris centered near the Pacific coast of Mexico.
The historical record, however, does show occasional contributions to tropical cyclones in the Gulf of Mexico and the Caribbean Sea from Northeast Pacific storms, or at least from the remnants of the storms. The NOAA Hurricane Research Division's "Frequently Asked Questions" provides the following information:
Northeast Pacific Hurricane Barbara in May 2013 made landfall on the Tehuantepec peninsula of Mexico. The circulation center dissipated as it moved over Mexico, but the moisture continued northward and contributed to the development of Tropical Storm Andrea in the Gulf of Mexico. Andrea eventually made landfall on the Gulf coast of Florida in early June.
Northeast Pacific Tropical Storm Alma in May 2008 became a remnant low as it crossed over Central America into the Northwest Caribbean. It merged with a tropical wave which generated Tropical Storm Arthur that eventually made landfall on the Caribbean side of the Yucatan peninsula of Mexico.
In June 1989, Northeast Pacific Hurricane Cosme made landfall on the Pacific coast of Mexico, crossed Mexico, and became Tropical Storm Allison over the Northwest Gulf of Mexico. Allison eventually made landfall in Texas.
An unnamed Northeast Pacific Tropical Storm in September 1949 crossed over Central America and Mexico, eventually becoming a major hurricane in the Gulf of Mexico that made landfall in Texas.
Another unnamed Northeast Pacific Tropical Storm in October 1923 crossed Mexico and became a hurricane in the Gulf of Mexico, eventually making landfall in Louisiana.