94L May Develop, Bring Heavy Rains to Mexico's Bay of Campeche Coast

A tropical disturbance over Mexico's Yucatan Peninsula (Invest 94L) has the potential to develop into a tropical depression on Sunday or Monday over the Gulf of Mexico's Bay of Campeche as the storm heads west-northwest at 10 mph. Satellite loops late Saturday morning showed the disturbance had developed a moderate degree of spin, with a few low-level spiral bands already apparent over the Bay of Campeche; Mexican radar out of Sabancuy showed a few heavy rain showers over the Yucatan Peninsula and adjacent waters. Invest 94L had only a modest amount of heavy thunderstorm activity, and development was being arrested by interaction with land and the presence of high wind shear of 20 - 25 knots. Water vapor satellite images showed a large area of dry air over the western Gulf of Mexico, which was also slowing development. Sea Surface Temperatures (SSTs) in the southern Gulf of Mexico are very warm, about 29 - 29.5°C (84 - 85°F), which will help development. An Air Force hurricane hunter aircraft is on call to investigate 94L on Sunday afternoon.


Figure 1. Latest satellite image of Invest 94L approaching the Gulf of Mexico.

Forecast for 94L
Steering currents favor a west-northwest motion for 94L across the Bay of Campeche, with landfall occurring between Tampico and Veracruz, Mexico on Monday afternoon or evening. In this region, 3 - 6" of rain are likely Sunday through Tuesday--with higher rainfall amounts to be expected if 94L ends up developing into a tropical storm. The 8 am EDT Saturday run of the SHIPS model predicted that wind shear would stay high, 20 - 30 knots, through Sunday night, then fall to the moderate range, 10 - 20 knots, on Monday, giving 94L a better chance to develop then. The Saturday morning operational runs of our three reliable models for predicting tropical cyclone genesis, the European, GFS and UKMET models, had one model--the European--supporting development of 94L into a tropical depression. However, about 40 - 50% of the 70 forecasts from the GFS and European model ensembles showed 94L developing into a tropical depression by Monday. The coast of the southern Gulf of Mexico along the Bay of Campeche is ringed by high mountains that tend to deflect the flow of air into a counter-clockwise path, adding spin that helps aid formation of tropical cyclones. In their 8 am EDT Saturday Tropical Weather Outlook, NHC gave 94L 2-day and 5-day development odds of 40%. I put these odds higher, at 60%, given the appearance of 94L on satellite imagery on Saturday morning, and the propensity of the Bay of Campeche to help spin up tropical cyclones. If 94L becomes a tropical storm, it would be named Danielle. I don't see heavy rains from 94L reaching South Texas.

Jeff Masters