Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
825 AM EDT Mon Jun 19 2017

Valid 00Z Tue Jun 20 2017 - 00Z Tue Jun 27 2017

Hawai'i will remain in a broad weakness between two large
subtropical ridges over the next 7 days. As an upper-level trough
amplifies north of the Islands through Tuesday, a surface front
will make some southward progress toward the Islands, but should
stall well before reaching even the northernmost Islands.  As a
result, the typical easterly trades should lessen some through
Thursday as the pressure gradient weakens in response to this
trough.  The deterministic model solutions as well as the
ensembles show generally good agreement on the large-scale details
of the pattern in the general vicinity of the state.  More
significant differences exist between the GEFS mean and EC mean
with respect to the developing surface low north of 40N, but this
should not cause much in the way of discrepancies for the Islands.

One additional feature of note is a weak upper low initially near
27N/132W. Models show good agreement that this feature will
initially move southwestward around the southern periphery of the
eastern Pacific high into Tuesday before turning more westward and
gradually dissipating by the end of this week.  This feature does
not appear to have higher PWs associated with it, so a significant
impact in terms of precipitation is not currently anticipated. 
Average PW values during most of the period should be around 1.25
inches, with moisture from the ITCZ remaining well to the south of
the Islands.

Hamrick