Tropical Storm Alpha, the 22nd named storm of the season, started out as a tropical depression in the central Caribbean on the 22nd of October 2005 southeast of the Dominican Republic. Alpha had little room to develop and after moving northwest crossed over the island of Hispaniola on the 23rd as a tropical storm with maximum sustained winds reported at 45 knots (52 mph) by NHC.

The Tropical Rainfall Measuring Mission (TRMM) satellite has been monitoring the extraordinary activity in the Atlantic. Armed with an array of sensors, TRMM can provide unique images and information on tropical cyclones over the global Tropics. This first image was taken by TRMM as Tropical Storm Alpha was approaching Hispaniola. The image was taken at 23:08 UTC (7:08 pm EDT) 22 October 2005 and shows the horizontal distribution of the rain intensity associated with Alpha. Rain rates in the central part of the swath are from the TRMM Precipitation Radar (PR), the only radar that can measure rainfall from space. Rain rates in the outer swath are from the TRMM Microwave Imager (TMI). The rain rates are overlaid on infrared (IR) data from the TRMM Visible Infrared Scanner (VIRS). TRMM reveals that Alpha is rather small and that it's circulation is not well developed. Alpha does not have a closed eye, and very little curvature is visible in the rain field. At the time of the image, Alpha was a minimal tropical storm with NHC reporting maximum sustained winds at just 35 knots (40 mph). However, as Alpha crossed Hispaniola, it triggered flash floods, killing 26 people in Haiti and the Dominican Republic.

The TRMM-based, near-real time Multi-satellite Precipitation Analysis (MPA) at the NASA Goddard Space Flight Center provides estimates of rainfall over the global Tropics. MPA rainfall totals due solely to Alpha are shown for the period 22 to 24 October 2005 with storm symbols marking the its track. Rainfall totals are generally less than 6 inches (green and blue areas) over Hispaniola, but terrain and deforestation make the area vulnerable to mudslides. After crossing the moutainous island, Alpha weakened back into a depression before being drawn into the circulation of Hurricane Wilma and a midlatitude low pressure system.

Beta, the 13th hurricane and 23rd named storm of the season, formed from a tropical wave into a depression on the evening of 26 October (local time) in the far southwestern Caribbean west of Nicaragua. Beta quickly became a tropical storm on the morning of the 27th as it drifted northward. The storm then took a more westerly course and began to intensify, becoming a minimal Category 1 hurricane in the early morning hours of the 29th. TRMM captured this image of Beta at 11:39 UTC (7:39 am EDT) 29 October soon after it became a hurricane. Although the center does not fall within the PR swath, the TMI shows that Beta has a closed eye structure with a solid ring of moderate intensity rain (green ring) surrounding the center. The overall rain area associated with Beta is not very large at this time however. As the system continued westward, it also continued to intensify and briefly reached Category 3 intensity on the morning of the 30th with sustained winds of 100 knots (115 mph). Beta made landfall later that day on the central east coast of Nicaragua as a Category 2 storm with winds estimated at 90 knots (104 mph) by the hurricane center.

MPA rainfall totals from Beta are shown for the period 27 to 31 October 2005. The heaviest amounts, on the order of 12 inches (red area), occurred off shore and were a direct result of Beta's slow forward speed. Rain amounts over land are generally 6 inches (green areas) or less. So far only 4 persons were reported missing as a result of Beta. Hurricane Mitch triggered massive mudslides in the region back in 1998, which led to a large loss of life.

TRMM is a joint mission between NASA and the Japan Aerospace Exploration Agency (JAXA).