Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
822 AM EDT Mon May 28 2018

Valid 00Z Tue May 29 2018 - 00Z Tue Jun 5 2018

The forecast period begins with a mid-tropospheric closed low
developing over the western portion of Hawaii by Monday night and
slowly retrograding to the west through Thursday to a position
near 170 degrees west, and upper level ridging to the east of the
Big Island.  The result will be an inverted surface trough over
the western islands followed by a stronger surface pressure
gradient by midweek as the surface high builds near 35 degrees
north, with the easterly trades increasing some as a result. 
Elevated PWs over the region early in the week will favor
increased chances for showers and thunderstorms.

The ensemble guidance is indicating another break in the
subtropical ridge by the weekend with a trough axis trying to
develop southward from the mid-latitudes.  The 6Z GEFS mean
appears to be more amplified with this next system than the EC
mean, with the attendant cold front expected to remain well to the
north of Hawaii.  This should be enough to relax the trades some
along with slight southeast veering and higher chances for rain.

D. Hamrick