Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 730 AM EST Thu Nov 16 2017 Valid 00Z Fri Nov 17 2017 - 00Z Fri Nov 24 2017 The main synoptic-scale system impacting the weather across Hawaii during the forecast period will be an upper-level cut-off/closed low forecast to drop southward from the higher latitudes toward Hawaii during the weekend. Model guidance during the past 24 hours has tracked the upper vortex farther to the south and more detached from the main flow to the northeast (particularly the ECMWF). It appears that a secondary cold front associated with the vortex could push through the island chain on Saturday with a brief period of enhanced shower activities. The vortex should then begin to pull out on Sunday, and should open up as a positively tilted trough further to the northeast by early next week. It appears that Hawaii will be situated between the marine stratus layer on the back side of this system and the plume of tropical moisture well to the south and east through the forecast period. Expect the trade winds to switch to more west to northwest directions as the system approaches during the weekend, followed by gradual resumption of the trades toward the middle of next week. By next Wednesday, the tropical moisture could begin to approach Hawaii from the south. Kong