Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 802 AM EDT Sun Mar 15 2015 Valid 00Z Mon Mar 16 2015 - 00Z Mon Mar 23 2015 Trades should slacken somewhat over the next couple days or so as elongated high pressure initially centered to the north/northwest of the state weakens and tracks eastward. The combination of relatively low deep moisture, as indicated by forecast precipitable water values remaining below an inch, and high heights aloft should keep shower activity light and scattered into Wed. Guidance maintains good continuity in expecting a front to reach the area around Wed-Thu with only a modest increase in moisture/rainfall. Behind the front the trades will strengthen as one high center should break off from a mean surface ridge and track to the north of the state Thu-Fri and remaining high pressure builds to a position north of the area by Sun. From Fri into the weekend guidance suggests that PWATs should be higher over the southeastern islands versus the northwestern islands. Therefore expect the windward focused showers that become established in that time frame to be best organized over the Big Island. While guidance agrees at the surface through next Sun, the 00z ECMWF shows much higher heights aloft versus other solutions including its ensemble mean next weekend. As a result would recommend a compromise among non-00z ECMWF guidance aloft at that time. Rausch