Guam/CNMI:  Rainfall on Guam during the 1st Quarter of 2006 was near normal at most locations. This was an artifact of a wet January, a normal February, and a very dry March. Most locations on Guam experienced rainfall totals between 10 and 12 inches during the 1st Quarter of 2006, with the highest total in the center of the island where 16.76 inches was recorded in Dededo (most of this – 10.14 inches – occurred in January). By mid-March, the island had dried sufficiently to allow the onset of almost daily wildfires. One large grassfire in the south of Guam on March 12th required evacuations from homes. No homes were damaged, but the fire scorched many acres of grassland and scrub forest.

Except for Tinian, the 1st Quarter rainfall totals at stations in the CNMI were generally slightly higher (approximately 15 inches) than those experienced on Guam (10-12 inches). The monthly distribution of the rainfall in the CNMI was similar to that on Guam where January was very wet, February was not as wet, and March was very dry. During the 1st Quarter of 2006, the Saipan International Airport (SIA) and Capitol Hill experienced 14.39 and 13.58 inches, respectively. These amounts, though relatively small, were high with respect to the typically very low amounts of rainfall in the CNMI during these dry season months.

For most of the 1st quarter of 2006, the Anatahan volcano, located about 90 miles north of Saipan and 200 miles north of Guam, was quiet. During late March and early April it began to emit a small plume of steam, gas and volcanic smog (vog). Some very hazy days on Guam and in the CNMI in early April can be traced back to Anatahan, with perhaps a contribution from Asian industrial smog. For the next few months it is possible that meteorological conditions may blow Anatahan vog over the CNMI and Guam, as happened in early April. Consult with the National Weather Service on current wind conditions that may bring Anatahan vog to nearby populated areas. More information on these events and current volcanic activity is available through a USGS and Hawaiian Volcano Observatory website, http://hvo.wr.usgs.gov/cnmi/ .

Guam and CNMI Rainfall Summary 1st Quarter 2006

Climate Outlook:

During La Niña years the tropical cyclone season in the western North Pacific basin is often delayed, and the number of tropical cyclones through mid-July is typically below normal. Also during La Niña years, the site of formation of the basin’s tropical cyclones is shifted to the west. For Guam and the CNMI, the typhoon threat is reduced. Thus, during all of 2006 (and especially during the months of September through December) two or three tropical storms and one or two typhoons should pass within 200 miles of any Guam and CNMI location. The odds of typhoon force winds (or greater) at any location on Guam or in the CNMI during any given year (status of ENSO not considered) are approximately 1 in 7. During El Nino years, the odds of typhoon force winds on Guam or on any individual island in the CNMI rise to about 1 in 3. During non-El Nino years the odds fall back to around 1 in 10. Dangerous surf from a typhoon does not require that the typhoon pass close to any location, so it is certain that at least one episode of dangerous typhoon-generated waves will occur. Every year several lives are lost due to hazardous surf and the rip currents produced by them.

Rainfall is anticipated to be below normal for Guam and the CNMI during May and June, and then return to near normal thereafter. Predicted rainfall for the Mariana Islands from May 2006 through April 2007 is as follows: