Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 714 AM EST Thu Jan 25 2018 Valid 00Z Fri Jan 26 2018 - 00Z Fri Feb 02 2018 Mean troughing aloft becoming established over or just west/northwest of the state will support a series of frontal approaches/passages along with periods of enhanced rainfall potential and winds that will vary on a day to day basis. From late this week into the weekend the Big Island and vicinity will be on the western periphery of enhanced moisture as denoted by 1.50" or greater precipitable water values. Expect the eastern islands to see the best chance for rainfall during this time frame given the combination of east-southeasterly low level flow and surface front crossing the islands during the weekend. Frontal passage will bring a drier trend along with a brief period of northeasterly to easterly winds Sunday-Monday. An upstream system will bring another front toward the western islands by Tuesday-Wednesday with timing differences appearing fairly typical for a forecast 5-6 days out in time. Dynamics aloft look stronger with this front versus its predecessor so the increased rainfall potential signaled by most model/ensemble guidance by midweek appears reasonable. In addition this front may decelerate/stall in response to the approach of another front by the end of the forecast period next Thursday. This evolution will have to be monitored in coming days, with some detail adjustments likely to occur. Based on current guidance spread an average of the GFS/ECMWF and their ensemble mean runs should provide a reasonable starting point to resolve detail differences through the forecast period. Rausch