Texas and Southeast Tropical Cyclone Threats?
Firsthand Weather is keeping a close eye on the tropics this week. There are two systems that may impact two separate regions across the United States this week.
Northern Mexico and Texas: Remnants of Harvey (Caribbean)
The first area we are monitoring is the Caribbean, which is where the remnants of Tropical Storm Harvey reside. The National Hurricane Center (NHC) is monitoring the remnants of Harvey, and currently is giving the low a 50% of tropical cyclone development over the next 48 hours and an 80% chance of tropical cyclone development over the next five days. The current analyses show decent spherical vorticity and light environmental shear. The main hindrance from immediate development is the speed at which the low is moving and the close proximity to land. There is likely not enough time, before the system crosses land, to undergo intensification into tropical cyclone status. This intensification may occur later in the week (more details below).
Area Being Monitored (NHC)
850mb Current Vorticity (University of Wisconsin)
Current Environmental Wind Shear (University of Wisconsin)
The remnants will move across the Yucatan Peninsula on Tuesday and cross into the Bay of Campeche (southwestern Gulf of Mexico) by Wednesday morning. While the remnants will likely remain below Tropical Depression/Tropical Storm criteria before moving across the Yucatan, heavy rainfall, rough seas, and gusty winds are possible across this area.
As the remnants move into the Bay of Campeche, environmental conditions appear to become favorable for development into a tropical cyclone. Global numerical guidance is indicating a steering pattern that may be favorable for a northwestern movement. The latest GFS and European have a general landfall between Tampico and Brownsville around Friday. This position would wrap in rich moisture into southern Texas and generate rough seas along the coast. With a cold front likely draped somewhere in the vicinity (southern Texas/central Texas), a flooding scenario could set up. The future intensity of the remnants and how much of a northerly component these remnants will take remain uncertain, but close monitoring is required.
GFS 850mb Vorticity (Friday Morning)
European 850mb Vorticity (Friday Evening)
Spaghetti Plot
Southeast (Florida): Invest 92 L (Atlantic)
The second area we are monitoring is the Atlantic (near the Bahamas), which is where a broad area of low pressure resides. The NHC is monitoring the low and currently is giving the low a 10% of tropical cyclone development over the next 48 hours and an 40% chance of tropical cyclone development over the next five days. The current analyses show a non-symmetrical/elongated vorticity, but environmental wind shear is light. Low-level convergence is also weak currently.
Area Being Monitored (NHC)
850mb Current Vorticity (University of Wisconsin)
Current Environmental Wind Shear (University of Wisconsin)
There is less confidence with this broad area of low pressure, which is visually displayed in the latest spaghetti plots. The timing and movement are big questions. The GFS shows this area of low pressure developing into a weak tropical cyclone (Tropical Depression). The European is not as bullish with tropical development, but shows a low developing with an upper-level trough off of the East Coast. Both scenarios indicate deep moisture being pulled into Florida, which will aid in heavy rainfall.
GFS 850mb Vorticity (Friday Evening)
European 850mb Vorticity (Friday Evening)
Spaghetti Plot
Firsthand Weather will keep a close eye on these two systems over the next few days. As confidence increases in the movement and intensity forecasts, we will provide updates.