Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 830 AM EDT Sat Jul 28 2018 Valid 00Z Sun Jul 29 2018 - 00Z Sun Aug 05 2018 While a broad upper ridge initially positions itself over the Hawai`ian island chain, the overall synoptic pattern should shift westward as the southern extension of weak height falls grazes the region. This is more easily shown on a 585-dm mid-level surface with perhaps some of the 00Z GEFS/ECMWF ensembles reaching Kauai and Ni'ihau by Day 6/7, August 3/4. Operational solutions are rather widely variable with the 00Z GFS being the most westward displaced. This trough axis should push west of the islands by next weekend as a 588-dm ridge shifts back toward the Big Island. At the surface, dueling areas of high pressure to the north and northeast of Hawai`i will continue to encourage a lengthy period of trade winds, generally around 20 knots for the most part. The 00Z ECMWF does show a slightly more amped up pattern early next week with speeds moving into the 25 to 30 knot range. Overall, little changes are expected given the configuration of the pattern. In terms of precipitation, the region will remain entrenched in rather high precipitable water air with expected numbers in the 1.50 to 1.75 inch range which is roughly 0.25 inches above climatology. Trade driven showers are likely each day, particularly during the potential enhancement early next week. Later on, enhanced moisture from the remnants of what is currently Tropical Depression Gilma could provide an additional focus for heavy rainfall. The guidance appears to agree with this overall forecast although the 00Z CMC does seem a tad dry at times. Rubin-Oster