Cyclone Monica intensified into the strongest storm of the season with wind gusts reaching 350 kph (~217 mph) as reported by the Australian Bureau of Meteorology's Cyclone Warning Centre. Fortunately, the Category 5 cyclone hit along the sparsely populated coastline of the Northern Territory, sparing the city of Darwin. The Tropical Rainfall Measuring Mission or TRMM satellite made several passes over Monica, during both early and mature stages of the storm. Monica originated in the Coral Sea below the southeastern tip of Papua New Guinea, becoming a minimal tropical storm on the 17th of April 2006. The storm tracked due west towards the Cape York Peninsula in Queensland and began to intensify. Since its launch back in the fall of 1997, TRMM has provided unprecedented and valuable information on tropical cyclones around the Tropics. With an active radar and a passive microwave sensor, TRMM can peer into the core of these storms and relay important details on storm structure and location to forecasters. The first set of images was provided by TRMM as Monica took aim at the coast of Queensland. The images were taken at 03:45 UTC on the 18th of April. The first image shows the horizontal distribution of rain intensity (top down view). Rain rates in the center swath are from the TRMM Precipitation Radar (PR), and 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). The curvature in the rain bands (blue arcs with embedded green and red areas) reveals the tell tale signs of a circulation. In addition, TRMM shows that Monica also has a partial eyewall containing a band of heavy rain (dark red arc). This structure is consistent with a developing but not yet mature tropical cyclone. At the time of this image, Monica was equivalent to a strong tropical storm with maximum sustained winds estimated at 60 knots (69 mph).

With its ability to look at precipitation structures in the vertical, the TRMM PR is able to provide this 3D image of Monica, which is concurrent with the previous image. The PR makes clear the presence of several tall towers (red surfaces) near the core of Monica that reach upwards of 17 km. These towers are associated with the heavy rainband that constituted the partial eyewall evident in the previous image. The presence of such towers near the storm's core have been associated with intensification. Tropical cyclones are fueled by the release of heat, and it is most effective when released near the core of the storm. The towers and heavy rain are signs of intense convection, which generates heating due to condensation, a process know as latent heating.

Monica struck the Cape York Peninsula just south of Lockart River on the afternoon of the 19th (local time) as a Category 3 cyclone. Almost exactly one month prior, powerful Cyclone Larry caused wide spread damage to the region farther south near the base of the peninsula. Monica weakened as it crossed the peninsula but reemerged over the warm waters of the Gulf of Carpentaria and began to re-organize and re- intensify. During the night of 20-21 April (local time), Monica regained Category 3 status and took a jog to the northwest. As it crossed the north-central part of the Gulf, Monica grew stronger and stronger.

VERY LARGE [43 mb] "3-D FLYBY" QUICKTIME animation (15 DBZ)	SMALLER [6 mb] "3-D FLYBY" QUICKTIME animation
SMALLER [1.3 mb] "3-D FLYBY" MPEG animation

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

Images produced by Hal Pierce (SSAI/NASA GSFC) and caption by Steve Lang (SSAI/NASA GSFC).