Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 714 AM EST Wed Dec 06 2017 Valid 00Z Thu Dec 07 2017 - 00Z Thu Dec 14 2017 Guidance continues to indicate that a series of features within a persistent east-central Pacific trough aloft will support the approach and in most cases passage of multiple fronts during the period. There is reasonable agreement in forecast details until some spread arises by next Tuesday-Wednesday. High pressure to the west-northwest of the state will extend a narrow ridge over the region over the next couple days, leading to fairly light winds. A front will approach from the north on Thursday but most likely stay just north of the northern islands. The next front will have stronger upper support and progress through the state during the weekend. These fronts should be accompanied by fairly light rainfall even with the possibility that some moisture may linger near the Big Island into early next week. The last front to affect the state will come through in the Tuesday-Wednesday time frame. Primary model differences involve the 00z/06z GFS runs becoming more amplified on the southeast side of the upper trough, leading to a farther southeast progression of the front. The 00z GEFS mean is a little more amplified with the trough than remaining guidance but otherwise aligns better with the 00z ECMWF/CMC and their ensemble means. Even within the preferred non-GFS majority scenario, there are some moisture and frontal timing differences that will take some time to be resolved. Stronger dynamics than with preceding fronts seem to favor a compromise for accompanying rainfall, between the 00z ECMWF and wetter GEFS/ECMWF means and 12z/05 ECMWF. Rausch