Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
252 AM EST Mon Dec 02 2019

Valid 00Z Tue Dec 03 2019 - 00Z Tue Dec 10 2019

Today's guidance shows better than average agreement for the
forecast covering the next seven days.  Trades should be fairly
persistent and moderate in strength through Friday as one surface
high well north of the islands on early Monday quickly weakens in
favor of an upstream high.  This latter high should reach north of
the islands by late week.  Trade winds will likely trend weaker
during the weekend and early next week as the high continues into
the eastern Pacific while a cold front settles very close to the
northern islands by next Monday.  There are some locally important
differences in precise frontal position at that time but spread is
sufficiently small to be well within typical guidance error for
day 7 forecasts--favoring an average of latest solutions for a
specific position.

Corresponding to the pattern evolution, showers will tend to favor
windward/mountain areas through late week.  Activity during
Saturday-Monday may see some degree of land/sea breeze influence
depending on exactly how weak the background trade flow becomes. 
Guidance is generally agreeable/consistent in depicting an
increase of moisture mid-late week ahead of an upper shortwave
that will likely pass over/north of the state around Friday.  The
combination of shortwave energy and greater deep moisture should
promote somewhat higher rainfall totals late in the week.  Expect
a drier trend for the weekend as the shortwave departs.  One trend
of note from yesterday is that the trailing upper ridge anchored
west of the area extends its influence farther east toward/over
the state.  Also by late in the period the 00Z ECMWF/12Z ECMWF
mean and 00Z CMC/CMC mean all extend the ridge eastward of the
latest GFS/GEFS mean by varying degrees.

Rausch