Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
251 AM EST Sun Jan 05 2020

Valid 00Z Mon Jan 06 2020 - 00Z Mon Jan 13 2020

Guidance agrees with the overall large scale pattern during the
period.  Building high pressure over the east-central Pacific from
Tuesday onward will take over after an initial high
reaches/weakens over the eastern Pacific, leading to strong trades
through next weekend.  An upper ridge that builds northeast of the
state by midweek should promote a westward drift of an upper low
whose associated moisture will likely promote increased
windward/mountain-focused rainfall over the state during the
latter half of the week and possibly into the weekend.  The
greatest forecast uncertainty continues to involve timing the
arrival of moisture from the east.  ECMWF runs have been
consistently on the faster side of the spread and the 12Z ECMWF
mean has adjusted faster to match the operational runs.  The 00Z
GEFS mean is about a day slower than the ECMWF but notable in
being faster than the erratic GFS (whose current 00Z run is
considerably slower than 24 hours ago after trending faster
previously).  For a single deterministic forecast the preference
would lean to the GEFS mean or a compromise between the GEFS mean
and ECMWF/ECMWF mean given the ECMWF consistency and ECMWF mean
trend.  Also worth noting, the GFS has the deepest solution for
the upper low by Fri-Sun. 

Rausch