Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 831 AM EDT Wed Sep 06 2017 Valid 00Z Thu Sep 07 2017 - 00Z Thu Sep 14 2017 Models continue to show a break in the ridge as an inverted upper trough drifts westward, generally staying just south of the islands. Toward the weekend, pronounced height falls begin to dip from a strong mid-latitude system. There is a growing consensus among the solution envelope to allow an elongated negative height anomaly to pinch off to the north of Hawai`i. The 00Z CMC/CMC ensemble mean are southwest of the strong model clustering as it brings the upper trough just to the west of Kauai. This appears to be an outlier at this point after comparison to the 00Z GEFS/ECMWF ensemble members. Currently, weak surface gradients will keep lighter winds in the forecast before a ridge to the north-northeast begins to strengthen. Toward the end of the work week, models enhance the climatological trades to around 20 knots before slackening again by early in the weekend as the surface high moves toward the eastern Pacific. Eventually a shift toward a more south-southeasterly flow regime is expected as warm advection ensues in advance of the aforementioned closed low. Regarding precipitation, the usual trade driven showers will be likely, particularly as the flow begins to strengthen in the next couple of days. The highest precipitable water values appear to stay just north and south of the state throughout the period. In spite of being in a relative minima, local pockets of enhanced showers may occur over the favored terrain and along any coastal mesoscale boundaries. Rubin-Oster