Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
711 AM EST Fri Nov 13 2015

Valid 00Z Sat Nov 14 2015 - 00Z Sat Nov 21 2015

Latest guidance maintains good continuity with the overall pattern
evolution over the next week though some detail differences
remain.  Over the next day or so high pressure to the
north/northeast of the islands will be replaced by a fairly strong
high building into the eastern Pacific, maintaining brisk trades
through the weekend.  Winds will then weaken and turn more
southeasterly as troughing aloft pushes a front toward the
northwestern islands.  While the initial dynamics will lift away,
trailing energy in the southern part of the trough will support a
surface trough over the islands late next week.

Showers should tend to be on the light side through the weekend as
precipitable water values decline to around 1.25 inches.  The band
of enhanced moisture associated with the front approaching from
the west may brush the northwestern islands but then only briefly
and is not forecast to reach any farther eastward.  From late Wed
onward, GFS/ECMWF runs have been fairly consistent over the past
couple days with bringing an area of enhanced deep moisture across
the state from the southeast.  00z/06z GFS runs are nearly a day
faster with the arrival of highest PWATs though.  Late in the
period the 00z ECMWF extends the upper trough to the west of the
islands farther southeast than other solutions so perhaps this
plays a role in the slower northwestward progression of the
moisture in that run.  So at least a compromise timing would be
reasonable for this moisture and the associated increase in
rainfall late in the week.

Rausch