Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 830 AM EDT Fri Sep 15 2017 Valid 00Z Sat Sep 16 2017 - 00Z Sat Sep 23 2017 Moving into the weekend, a broad 594-dm mid-level ridge sets up across the mid-latitudes of the central Pacific. By the early to middle part of next week, a slow-moving easterly wave begins to approach the Hawai`ian island chain but should general remain east of the region. Models eventually show this feature shearing with residual vorticity centers drifting north of the state by September 21/22. Farther upstream, amplified flow begins to move toward the International Dateline late in the forecast. However, this system should remain well north and west of the region. At the surface, a convergence zone lingers north of Kauai but will quickly lift away later today. In its wake, a strengthening anticyclone to the north-northeast will lead to a notable uptick in the trade winds with speeds expected to reach the 20 to 25 knot range. As the surface high moves farther northeast, expect pressure gradients to weaken a bit leading to a slight decrease in the strength of the trades. In terms of precipitation, the usual windward showers will be likely although precipitable water values generally remain on the lower side, generally ranging from 0.75 to 1.25 inches throughout the forecast. Rubin-Oster