Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 754 AM EDT Sun Apr 14 2019 Valid 00Z Mon Apr 15 2019 - 00Z Mon Apr 22 2019 An elongated upper-level trough situated east of Hawaii early this morning is expected to gradually move eastward away from the state through the next couple days. Models/ensembles show broad agreement on this evolution, with relatively minor differences primarily in the depth of the feature. At the surface strong high pressure anchored well northeast of the state is expected to keep moderate trades in place through Monday, before these begin to relax by midweek as the surface high weakens and moves east. Instability and moisture associated with the upper-level trough will be sufficient to produce scattered showers and even a few thunderstorms, which should focus primarily across windward locations in eastern portions of the state. Areas of locally heavy rainfall will still be possible. By the middle of the week, as the upper trough moves east, light to moderate trades are expected to continue with limited moisture bringing more isolated windward shower activity. A rebuilding surface high north of Hawaii by late in the week should bring a slight increase in strength of the trades. Any influence from a fairly active frontal zone across the north central Pacific appears likely to remain north of Hawaii into next weekend. Ryan