Tropical Update

Sad news over the weekend involved the death of a 5-year old boy at the Huntsville Airshow. A localized microburst occurred at the event and blew over several tents and injured 12. The storm was produced by the deep trough and strong cold front that swept through the region. My thoughts and prayers are with the family and friends of the young boy.

The tropics are beginning to get heat up. The Eastern Pacific has been active for the last couple of weeks with Tropical Storms Boris and Douglas currently churning. Both storms only pose a threat to shipping at least point. The Atlantic basin looks get in on the action this week with two tropical disturbances showing some potential for further organization.

The first disturbance moving through the Lesser Antilles is producing heavy rains and gusty winds. Hewanorra, St. Lucia measured a little over 0.50" of rain with sustained winds up to 28 mph out of the E and ENE. Thunderstorm activity increased today, but the system is currently experiencing 20-30 knots of southwesterly wind shear due to an upper-level trough to its west. This is a bit too high for significant development, but if the upper trough dissipates or moves further west, this would allow the shear to relax and strengthening would be more likely. Water temperatures are supportive of tropical development with SSTs in the lower 80s in the eastern Caribbean. In fact, the SHIPS model calls for slow strengthening of this system over the next 24 hours, and it even develops the wave into a named storm within 48 hours. I think that may be a bit optimistic given the current wind shear in place, but a lessening of the shear would allow for development. Regardless, this system bears watching as it moves to the WNW. If the system does develop, the forecast upper-level pattern would more than likely keep the main threat to Mexico.

A larger and much healthier looking tropical wave is centered about 220 miles southeast of the Cape Verde Islands. It's climatologically early to be looking this far east for tropical development, but this system appears impressive on satellite with deep convection clustered the center. SSTs near and to the west of the wave are marginal (~79 deg F) for development, but some slow strengthening is possible as the system moves quickly to the west along the southern periphery of the subtropical high. The marginal SSTs may be compensated by weak/moderate wind shear (10-15 knots) and an absence of Saharan dust/dry air. The Saharan air is well to the north of the system, and wind shear will become very weak as the system moves to the west. These two factors argue for continued strengthening, but the marginal SSTs should prevent significant development for the next several days. However, SHIPS calls for the wave to be a named system by 48 hours and up to hurricane intensity within 72 hours. I think this is overly aggressive, but I wouldn't be surprised to see a tropical depression and possibly a weak tropical storm form within 48 hours. Computer models are unanimous at this point in recurving the system in about 5 days.