Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
808 AM EDT Sun Apr 16 2017

Valid 00Z Mon Apr 17 2017 - 00Z Mon Apr 24 2017

Drying aloft occurs through next week with layer relative humidity
dropping to below 50 percent as a low level ridge persists north
of the islands. Showers are focused primarily in windward
locations with moderate trades.

On Wed and Thu the next deep layer trough is forecast to approach
from the west, with a surface cold front gradually weakening as it
crosses the islands.   The GFS and ECMWF show pockets of enhanced
precipitable water, with the GFS/ECMWF showing around 1.5 inches
near the boundary.
Pre-frontal convergence should produce an uptick in shower
coverage and amounts.
Even though the front will have decayed next weekend, the residual
low level trough provides a focus for showers into next weekend.

The models remain in good agreement with the forecasts among the
GFS/GEFS Mean/ECMWF/ECMWF ensemble mean/Canadian global regarding
the approach of the front, arrival, and dissipation. 

Next weekend the majority of solutions show another low level
ridge building north of the islands and trade winds becoming
re-established over the region, gradually increasing to normal to
brisk Sun 23 Apr and into early next. 

Petersen