Tropical Storm Alma - Meteorological History

Meteorological History

Towards the end of May 2008, computer hurricane models forecast the development of a broad low pressure area to the southwest of Central America. On May 26, a large trough extended from the southwestern Caribbean Sea across Costa Rica into the eastern Pacific Ocean, forming a broad low pressure area across the region. A scattered area of strong convection developed, partially in association with the Intertropical Convergence Zone. Located within an area of weak steering currents, the disturbance remained nearly stationary, and on May 27 its shower activity increased in organization. Initially the system consisted of several cyclonic swirls, of which the most pronounced one was located about 340 miles (550 km) west-southwest of San José, Costa Rica. The system gradually became better organized, and with a sufficiently well-developed circulation and convective structure, the National Hurricane Center (NHC) classified the system as Tropical Depression One-E at 0300 UTC on May 29, about 105 miles (165 km) west-northwest of Cabo Blanco, Costa Rica.

With a mid-level ridge located in the Gulf of Mexico, the depression drifted generally northward through an area of warm water temperatures and low wind shear. Initially its convection was weak and confined to a few rainbands far from the center. As such, intensification was not expected beyond minimal tropical storm status. However, the system quickly developed intense thunderstorms near the center with increased banding in its southern semicircle, and at 1500 UTC on May 29 the NHC upgraded the depression to Tropical Storm Alma, about 55 miles (85 km) southwest of Managua, Nicaragua. Its intensity was set at 45 mph (75 km/h), and the storm was forecast to intensity only slightly more before moving ashore. However, one hour after it was upgraded to tropical storm status, the NHC re-assessed the intensity as 65 mph (100 km/h), citing updated observations from satellite imagery and QuikSCAT. An eye feature formed, surrounded by a very tight ring of convection, and at around 1900 UTC on May 29 Alma made landfall near León, Nicaragua as a strong tropical storm. The storm quickly weakened after moving ashore, though a small area of thunderstorms persisted as it crossed into the mountainous region of southern Honduras. After passing near Tegucigalpa Alma weakened to tropical depression status, and at 1500 UTC on May 30 the cyclone dissipated near the border of Honduras and Guatemala. On May 31, after crossing Central America as a low pressure area, Alma's remnants moved into the Gulf of Honduras and spawned Tropical Storm Arthur.