Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 714 AM EST Fri Nov 24 2017 Valid 00Z Sat Nov 25 2017 - 00Z Sat Dec 02 2017 ...Heavy rain possible next week over the Big Island and perhaps Maui... Upper high to the northwest of Hawai'i will weaken and move westward in the short term, allowing troughing to settle over the region over the region. The sfc high to the northwest of the region will be reinforced this weekend and slide southeastward then eastward along 33N next week which will maintain breezy/windy trades into next week. Light to scattered windward/mauka showers are expected with only some spillover to leeward areas possible as the overall air mass remains dry. Next week, the trough or weakly closed low will continue to push westward, allowing moisture from the ITCZ to creep northward. This will increase rain coverage from southeast to northwest over the island chain. The GFS/ECMWF have wavered on how much to increase precipitable water values but the latest 00Z ECMWF was more in line with the multi-center ensemble mean whereas the GFS showed lower PW values. In addition, the 00Z GEFS M-Climate QPF percentiles were at the 99th percentile very near the southeast islands next Wed-Fri, so the potential remains for at least some modest to locally heavy rain next week, especially over the Big Island and Maui. Fracasso