Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 807 AM EDT Mon Sep 11 2017 Valid 00Z Tue Sep 12 2017 - 00Z Tue Sep 19 2017 Through about Wednesday-Thursday expect fairly light low level flow with sea/land breezes having the primary influence on shower activity. An upper trough settling to the north of the state will reflect at the surface as wavy front that should stall just northwest of the islands. With the islands under the southern periphery of the upper trough and precipitable water values at or above 1.50 inches over some areas, rainfall could be locally heavy. From Friday onward expect a return to at least moderate trades as the lingering surface front to the northwest weakens and high pressure builds across the central Pacific. For this time frame shower activity should focus more over windward terrain and be a little lighter as PWATs decrease somewhat. Latest GFS runs are somewhat slower to decrease moisture than ECMWF runs though. One change in the guidance from yesterday is an increased potential that weak residual energy from the upper trough may close off a low that tracks either over or northwest of the islands in the Saturday-Monday time frame. The 00z GFS/GEFS mean track the feature over the western islands while the 06z GFS and 00z ECMWF/ECMWF mean/UKMET track farther west. On the other hand the 00z CMC is farther east than other guidance. All of these solutions are within the full 00z GEFS/ECMWF/CMC ensemble spread so confidence in any specific scenario is very low. Rausch