Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 819 AM EDT Sat Jul 08 2017 Valid 00Z Sun Jul 09 2017 - 00Z Sun Jul 16 2017 Across the mid-latitudes of the central Pacific, a mean mid/upper-level ridge generally remains anchored over the region. Southward into the subtropical Pacific, a series of weaknesses are noted to be tracking westward toward the Hawai`ian island chain. The elongated region of troughing appears to remain just east of the islands throughout the period with some west-east model spread noted in the guidance. More specifically, it is mostly the 00Z ECMWF ensemble members which depict this feature lingering east of 150W while the 00Z GEFS members are somewhat more suppressed with the southward extent of this trough axis. At the surface, a broad anticyclone remains in place across the central Pacific with pressures gradually increasing into early next week. This will lead to an uptick in the intensity of the climatological trades with expected wind speeds around 20 knots or so by the early/middle part of next week. The 06Z GFS solution shows some weakening in the trades toward the end of the forecast period given it centers the surface ridge a bit farther north than other model solutions. Regarding precipitation, models show an increase in rainfall coverage and intensity moving toward the Tuesday/Wednesday time frame. This is in conjunction with a spike in the precipitable water values across the region with readings moving above 1.50 inches. The 06Z GFS is a bit more robust in forecast rainfall amounts, particularly over the northern most islands. It will take a couple of additional days to completely scour out the enhanced moisture plume. By Friday and into the following weekend, a return to more seasonal conditions is expected. Rubin-Oster