| http://www.cpc.ncep.noaa.gov/products/precip/CWlink/ghazards/...........Global Tropics Hazards and Benefits Outlook Discussion Last Updated: 08.20.13 Valid: 08.21.13 - 09.03.13 The MJO continued to remain weak during the past seven days. However, dynamical model MJO forecasts indicate an organizing MJO signal during Week-1 with an eastward propagation across the western Hemisphere during Week-2. The western and central Pacific were active during the past week with Tropical Storm Trami developing on August 17, northeast of Luzon. Trami is forecast to become a typhoon before tracking west across Taiwan and making a second landfall in southeast China. Meanwhile, two Tropical Storms and a Tropical Depression developed near the Date Line over the central Pacific. Tropical Storm Erin was a weak and short-lived tropical cyclone (TC) across the far eastern Atlantic. The focus for tropical cyclogenesis is expected to shift from the western and central Pacific to the east Pacific and Atlantic basins during the next two weeks. A tropical cyclone (TC) is likely to develop between 15-20N/105-115W across the east Pacific with an expected track north near the Baja peninsula. This general north-northwest track is supported by most model guidance and is consistent with previous GFS model solutions. A moisture surge north from the Gulf of California is likely to follow, which increases the risk of heavy rainfall and flash flooding across the desert Southwest. The 12Z GFS from August 20 indicates a second tropical cyclone developing southwest of the first TC, near 15N/115-120W. Therefore, moderate confidence exists for TC development is forecast across this region. Elevated chances of additional TC development are expected to continue due the organizing MJO signal propagating from Phase 1 to 8. The large scale environment is expected to become more favorable for TC development across the main development region (MDR) of the Atlantic basin later in Week-1 and continuing into September. MJO composites for Phase 1 along with model tools support the moderate to high confidence for TC formation during the next two weeks across the MDR region of the Atlantic. Below-average rainfall is favored from southern India to Southeast Asia as the suppressed phase of the MJO is expected to become better organized during Week-1. Heavy rain is forecast to accompany the westward track of Tropical Storm Trami, over Taiwan and southeast China, while the cyclonic flow around Trami renews flooding concerns across the northern Philippines. During Week-1, model guidance and MJO precipitation composites for Phase 1 favor below-median rainfall across South Asia, Southeast Asia, and the equatorial Pacific. A low-frequency mode supports above-median rainfall to the southwest of Java during Week-1 with increased convection expected later in Week-2 across the central Indian Ocean. The expected evolution of the MJO favors above-average rainfall across Mexico during the next two weeks, while TC activity over the east Pacific, coupled with southeasterly flow, favor above-average rainfall extending north to the southwestern U.S. The Sahel region of western Africa is expected to remain wetter-than-normal as robust easterly waves progress across this area. |