Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
817 AM EDT Thu Jul 06 2017

Valid 00Z Fri Jul 07 2017 - 00Z Fri Jul 14 2017

The guidance shows relatively good agreement at 500 hPa and the
surface over the next week.  large mid-level subtropical high that
is northwest of the Islands should remain in place through the end
of the week and then expand eastward around the 35th parallel per
the latest ensemble means.  There is a greater signal in the
guidance of a TUTT low at 200 hPa just south of the ridge axis
between 25 and 30 degrees north that will serve to increase
westerly wind in excess of 50 knots by the middle of next week,
which shows up weakly in the 500 hPa pattern. Trade winds should
increase in magnitude from Sunday onward as the tail end of a
front retrogrades as an inverted trough north and northwest of the
50th state.

Precipitable water values should remain near 1.25"/close to
average through Sunday night.  There is still the potential for an
axis of enhanced moisture to reach the Islands Tuesday and/or
Wednesday with precipitable water values of ~1.75" as the remnants
of a northeast Pacific tropical cyclone attempt (currently near
18N 122W) move westward past the 140th meridian within a sheared
environment, possibly moving by Hawai'i as a "screaming eagle"
feature.  Windward showers, with some local enhancement early next
week as precipitable water increases with the surface trough
passage. 

Roth/Hamrick