Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
715 AM EST Mon Nov 05 2018

Valid 00Z Tue Nov 06 2018 - 00Z Tue Nov 13 2018

During the first part of this week expect a gradual lighter trend
for trade flow as eastern Pacific high pressure drifts
northeastward.  Windward-focused showers will likely trend lighter
as well with precipitable water values declining to around normal
values.  Guidance continues to show an upper trough amplifying to
the north and west of the state with a leading cold front
approaching the main islands from the northwest late in the week. 
Thus during mid-late week expect prevailing low level winds to
become lighter and oriented from the southeast, allowing for
potential of more land/sea breeze influence on shower activity. 

From Friday onward the GFS/ECMWF and their ensemble means, along
with the UKMET to a reasonable degree, show fairly good continuity
and agreement regarding progression of the upper trough and
surface front--the latter crossing the main islands in the
Friday-Saturday time frame.  The one notable difference is that
the 00Z ECMWF is somewhat faster than the GFS and the two means
with the front so preference would be to lean more than halfway
toward the other solutions in that cluster.  Ahead of the front
expect a period of enhanced rainfall potential, perhaps to a
somewhat greater degree than suggested by some of the model
guidance.  After frontal passage trailing high pressure will
support moderate to brisk northeasterly winds.  The relative
stability/consistency in the GFS-ECMWF cluster from yesterday
provides improving confidence in the forecast.  There are still
lingering question marks as the CMC and its ensembles hold the
upper system/cold front farther westward due to lesser amplitude
of North Pacific flow.  The CMC/CMC mean tend to be less correct
when the other solutions advertise an amplified pattern so the CMC
scenario should have fairly low probability. 

Rausch