Hawaii Extended Forecast Discussion NWS Weather Prediction Center College Park MD 719 AM EST Sun Jan 01 2017 Valid 00Z Mon Jan 02 2017 - 00Z Mon Jan 09 2017 A very strong 500 hPa positive anomaly near the Alaska panhandle forced by an amplified trough west of the International Dateline teleconnects to a deep cyclone under the ridge's base somewhere to the north of Hawai'i. While separation between such systems is normally 20 degrees latitude, the breadth/strength of the positive anomaly is forcing greater separation than usual. The negative anomaly under its base could be composed of multiple, merging closed lows which is advertised nicely by the global guidance. The global and ensemble mean guidance remains relatively close here, with another system offshore the Pacific Northwest potentially tugging the system north of Hawai'i eastward from Tuesday onward -- a compromise of the 00z Canadian/00z ECMWF is advised as they lie closest to the ensemble means and keep separation between the closed cyclone north-northeast of the archipelago and troughing offshore the western United States coast the longest. A second system diving west of Washington Saturday appears to complete the job of phasing with the remains of the closed cyclone. Overall, the 50th state should be under the influence of an upper trough near to east of the state from Tuesday night onward. The trades should be weaker than average due to the proximity of the deep cyclone north-northeast of Hawai'i. With the deep moisture offset east of the archipelago, a generally quiet pattern is expected with windward focused showers less numerous than usual, mainly expected late today into Monday. A cold front/shear line will drag out of the Papahanaumokuakea National Marine Monument into the northwestern main islands Tuesday/Wednesday, with the boundary clearing the Big Island Thursday/Friday, which could increase rain chances back towards climatological norms Tuesday into Thursday as the feature passes by. A new frontal zone moves into the Papahanaumokuakea National Marine Monument next weekend as a strong and negatively tilted upper trough undercuts a slightly retrogressive but highly amplified ridge near the Alaskan peninsula. Roth