A strong tropical wave continues to show signs of organizing into the next tropical storm of the Atlantic Basin near Mexico's Yucatan Peninsula this week.
The combination of very warm water and lessening wind shear should allow the tropical wave, labeled as 90L, to organize into a tropical depression or storm.
Wind shear is the changing of speed and direction of winds at different layers of the atmosphere. Strong wind shear can prevent tropical development or shred apart mature tropical storms or hurricanes.
Development may occur prior to the system reaching the Yucatan Peninsula later on Monday.
“We anticipate 90L to at least graze the northern coast of Honduras on Sunday night and Monday before hitting the Yucatan,” AccuWeather Meteorologist Brett Rossio.
Regardless of development, 90L will spread drenching rain squalls across Central America and the Yucatan Peninsula. Localized flash flooding may result, as well as sporadic power outages. Rough seas will endanger operators of small craft and swimmers.
Moisture streaming toward the system may also fuel locally flooding downpours across the southern Central American countries during this time.
"Mudslides could get triggered in the higher terrain of Central America," AccuWeather Meteorologist Eric Leister said.
"Downpours will first reach the eastern Yucatan on Monday afternoon with the worst impacts across the peninsula on Monday night into Tuesday," he said.
The risk for flooding rain, damaging winds and rough seas will increase around 90L as it strengthens.
If 90L fails to develop before reaching the Yucatan, Rossio expects it will have no trouble ramping up into a tropical storm over the warm waters of the southwestern Gulf of Mexico at midweek.
“Anomalously warm water and very low wind shear would promote rapid strengthening of 90L,” Rossio said.
The next tropical storm in the Atlantic Basin would acquire the name “Franklin.”
Only if 90L tracks more to the west than northwest and fails to enter the Gulf of Mexico would the window for development or re-strengthening close.
In the more likely scenario that 90L re-emerges over water, it could even become a hurricane if it is a tropical storm before reaching the Yucatan and remains over water long enough prior to slamming into the eastern coast of Mexico either on Wednesday night or Thursday.
Residents and visitors from Veracruz to near Tampico, Mexico, should start making the necessary preparations for the possibility of 90L making landfall with flooding rain, damaging winds and an inundating storm surge.
In addition to flooding, 90L may also trigger mudslides, tree damage and lengthy power outages. Damage to weak structures could also occur.
High pressure nosing over the northern Gulf of Mexico is expected to prevent 90L from turning northward to Texas. However, rain may still graze South Texas and rough seas may endanger swimmers all along the state's coastline as 90L moves into Mexico.
Meanwhile, a disorganized system that has been dubbed 99L in the central Atlantic will continue to be monitored for development as it tracks westward this week.
The system is over the warm waters of the Atlantic and is not being affected by disruptive winds. The main inhibitor to development is the presence of some dry, stable air.
If 99L develops and/or survives, then it is likely to approach the Windward and Leeward islands around Wednesday night. Parts of these islands are likely to experience an uptick in showers and thunderstorms at the very least during that time.
"The exact track of 99L in relation to the proximity to the islands will depend on how quickly the system strengthens," AccuWeather Senior Meteorologist Alex Sosnowski said.
A weak and poorly organized system is more likely to track to the west. A developed system is more likely to track north of west.
"Even if 99L develops and strengthens over the central Atlantic Ocean, that trend may end or reverse before it reaches the Lesser Antilles,” Rossio said. "The system may encounter stronger winds aloft by midweek and may then track close enough to the mountainous Greater Antilles later in the week."