Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 AM EST Sun Dec 18 2016 Valid 00Z Mon Dec 19 2016 - 00Z Mon Dec 26 2016 ...Heavy rains over the Big Island... Models and ensembles offer below normal forecast spread and uncertainty for the Hawaiian weather pattern this week. Satellite imagery shows a closed low over the western islands. High surf advisories are in effect for portions of the western and southern islands and a flood advisory is in place for the Big Island. Heavy rainfall potential has increased today...especially over the Big Island as shown by radar...as the closed low digs over the western islands. The low lingers and gradually weakens just southwest of the state early next week. This significant feature has induced a well organized surface low to tap/pool deep tropical moisture from the southeast as shown in precipitatble water loops. The heaviest rain threat should focus over the Big Island with max terrain lift and precipitatble water values forecast to rise to 1.75". More modest rainfall potential should build westward across the state early next week before a drying trend and return of seasonal trades as high pressure settles well northeast of the state. Models and ensembles are more varied with amplified late week flow over the mid-lower Pacific latitudes, but favor subsequent closed low digging farther westward from the state than the current system concurrent with subtropical western Pacific ridge retrogression. Schichtel