Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 815 AM EDT Sun Aug 21 2016 Valid 00Z Mon Aug 22 2016 - 00Z Mon Aug 29 2016 Guidance maintains good agreement and continuity for the general pattern at the surface and aloft, while some differences persist for the axis of deepest moisture during the first half of the week. Still expect trades to fluctuate based on combined strength and proximity of eastern Pacific high pressure. Winds should trend gradually weaker from now to about 12Z Tuesday, stronger into Thursday, and then gradually a bit weaker during Friday-Saturday. GFS/ECMWF runs still disagree on the alignment of highest precipitable water values around Sunday night-Wednesday though ECMWF trends/GFS continuity seem to be leaning somewhat more in the GFS direction. The 00Z ECMWF still shows its highest PWATs just west/southwest of the islands while GFS runs are over the islands. However the current ECMWF axis is close enough to the islands to position higher PWATs over the state than its run from 24 hours ago, and in fact with higher PWATs than the GFS over some areas. Anomalies for PWATs from various guidance sources continue to reach or exceed 2-3 standard deviations above normal. The available deep moisture along with a modest weakness aloft, as well as potential sea breeze boundaries allowed by relatively weak trade flow, may promote some areas of heavy rainfall during the first half of the week. Wednesday appears to be the transition day. GFS runs keep high PWATs over the area while the 00Z ECMWF already starts the drying trend. Nearly all guidance shows ridging beginning to build over the area on Wednesday as well. There is better agreement on drier conditions and more windward focus for what showers exist late in the week. Rausch