Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 830 AM EDT Fri Aug 18 2017 Valid 00Z Sat Aug 19 2017 - 00Z Sat Aug 26 2017 Models highlight an inverted upper trough slowly sliding toward the west although the core of the positive vorticity advection should stay north of the Hawai`ian island chain. This feature should continue to push toward the International Dateline while an expansive 594-dm mid-level ridge sets up across the mid-latitudes. To the south of Hawai`i, the Central Pacific Hurricane Center has continued to monitor an area of disturbed weather approximately 600 miles southeast of Hilo. Based on this forecast, it appears conditions remain unfavorable for any further development while also remaining well south of the region. At the surface, persistent ridging to the north will keep the usual trade wind regime in place with winds generally in the 10 to 15 knot range. By Tuesday, a strengthening of the parent anticyclone will lead to an uptick in the low-level winds, likely up to 20 knots or so. It appears this increase in the trades should remain a fixture in the forecast throughout much of next week. Considering the precipitation forecast, windward showers will be the norm early on with a likely increase in coverage and intensity expected by late Sunday/early Monday as precipitable water values rise above 1.50 inches. This moister regime should continue through mid-week before drier air infiltrates the region. During the period of increasing tropospheric moisture, models do show an increase in forecast rainfall amounts, particularly across the Big Island as well as over Kauai. Rubin-Oster