Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
716 AM EST Fri Jan 02 2015

Valid 00Z Sat Jan 03 2015 - 00Z Sat Jan 10 2015

Strongly amplifying energy aloft initially northwest of the region
will bring a sharp and deep trough across the state during the day
Sat.  Ahead of this trough, surface low pressure is expected to
track just north of Kauai late Fri with a trailing strong cold
front crossing the islands Fri-Sat.  This system has the potential
to generate strong convection, especially with respect to winds,
and briefly intense rainfall.  Progression of activity should
temper total rainfall amounts though.  The one guidance difference
at this time is with the amplitude of the upper trough by late
Sat, with 00z ECMWF/ECMWF mean solutions the most extreme yielding
a pocket of 500mb height anomalies that would surpass six standard
deviations below normal.  GFS guidance reaches at least 5 stdevs
below normal so this will be an extreme event in any case with a
compromise approach best at this time given the similarity in
guidance before differences develop after 12z Sat.

Strong northwesterly low level winds during the weekend will trend
toward more typical moderate trade flow heading toward the middle
of next week as high pressure tracks eastward along 28-32N
latitude.  Ahead of this high a weak and relatively dry front may
reach the islands around Tue.  There is good model/ensemble
agreement that departing high pressure and a weak approaching
front should lead to lighter trades by next Thu-Fri.  Expect
relatively low precipitable water values over the area during most
of next week so any shower activity should be on the light side.

Rausch