Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 807 AM EDT Fri Jul 14 2017 Valid 00Z Sat Jul 15 2017 - 00Z Sat Jul 22 2017 Models have been fairly consistent in maintaining some sort of positively-tilted upper trough extending over much of the central subtropical Pacific. Within this weak negative height anomaly, the most discernible future will be a compact closed low. However, this should remain well to the northeast of the Hawai`ian island chain. By the early to middle part of next week, recent guidance depict this trough should migrate westward toward the International Dateline with shortwave ridging noted over the islands. This is in advance of the approach of what should be Hurricane Fernanda based on the latest National Hurricane Center forecast. While their track forecast concludes on Day 5/Wednesday, recent models still have the cyclonic circulation southeast of Hawai`i by next Friday. Looking to the surface, a persistent anticyclone to the north will favor moderate trade winds for an extended period of time, possibly sustained in the 15 to 20 knot range. By Tuesday/Wednesday of next week, it appears the primary surface ridge will split with the more dominant region of high pressure just east of the International Dateline over the mid-latitudes. However, this shift in the pattern does not alter the continued trade wind regime in a significant way. By next Friday, depending on the track of the tropical cyclone, some uptick in the trades may be possible. Considering precipitation threats across the state, the highest precipitable water air should remain west of the region for a majority of the period. Some hints at an increase in moisture is possible by mid-week although models do not appreciably raise forecast rainfall amounts. Generally speaking, expect the usual windward showers with local orographics and mesoscale boundaries likely enhancing activity. Rubin-Oster