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

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

Flow aloft between a narrow ridge north-northwest of the state and
an eastern Pacific upper low will push a weak front and
accompanying showers through the area around Tuesday.  The trend
toward lower precipitable water values will generally continue
behind the front as an elongating upper trough takes shape just
north of the area Wednesday into early Friday.  The upper trough
may hold moderate amounts of moisture over the Big Island for a
time but elsewhere the low PWATs should help to offset any
instability thus keeping shower activity on the light side.  This
trough should pass by on Friday and lift away thereafter.  Then
models/ensembles differ on some details of flow aloft but point to
stable or slightly rising heights next weekend into early next
week.  Central Pacific high pressure and a western Pacific high
that merges with it Thursday-Friday will promote moderate to brisk
northeasterly trades during the next few days.  By Saturday-Monday
guidance varies a bit on the strength/shape/position of high
pressure but there is agreement in principle that the surface
ridge will elongate eastward to turn trades more easterly over the
islands.  Expect a continuation of mostly light and windward
focused showers through this time frame.

Rausch