Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
239 AM EST Thu Jan 28 2021

Valid 00Z Fri Jan 29 2021 - 00Z Fri Feb 05 2021

Expect reinforcing high pressure well north of the state to
maintain brisk to strong trades into the weekend, supporting a
windward/mountain focus for showers.  Most rainfall should be in
the lighter half of the spectrum as consensus shows precipitable
water values moderately below normal from late this week into the
weekend.  Moisture may recover toward climatology by the start of
next week.  Early next week winds should weaken and trend more
southeasterly as high pressure progresses eastward and a cold
front approaches from the west.  Guidance agrees that this front
will reach into the main islands by midweek, accompanied by
potentially moderate to heavy rainfall and some thunderstorms. 
Prior forecasts valid for Wednesday have converged more by way of
the GFS trending slower with the front.  By next Thursday guidance
begins to diverge for exactly how far eastward the front
progresses, in response to differences in evolution for the
supporting upper trough.  While they have their detail
differences, the main theme among the 00Z ECMWF/CMC/CMC mean and
12Z/27 ECMWF mean is for a somewhat sharper and slower upper
trough than the 00Z GFS/GEFS mean.  The larger ECMWF cluster and
the slower GFS trend from yesterday would seem to recommend
leaning somewhat more toward that majority by next Thursday--which
could support some lingering rainfall over eastern parts of the
state.

Rausch