Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
753 AM EDT Tue Sep 30 2014

Valid 00Z Wed Oct 01 2014 - 00Z Wed Oct 08 2014

The 30/00 UTC GFS/GEFS and ECMWF/ECENS were very much in mass
field agreement heading into the weekend. Both migrate a low
pressure area near 45N 170W northeastward into the north central
Gulf of Alaska and rotate a surface trough south-southeastward
into the Subtropics along 30N 160W. This surface
trough---migrating gradually eastward along 150W into early next
week and displacing the Subtropical Ridge. Beyond day 6 (Monday),
a broad cyclonic flow and deep surface cyclone sets up in the
southern Bering Sea and central Aleutians. This feature will
continue displacing the Subtropical Ridge eastward---and closer to
the California and Baja California coastlines.

Appears that trades remain slight and a persistence forecast may
be in order. Early in the forecast period, the sensible weather
forecast will be tied to a mid-level circulation invof 23.5N
154W---drifting very slowly northwestward to the immediate north
of Hawai'i. This circulation creates a west-to east band of
mid-level shear and isolated deep convective rain bands for the
western half of the state. This quasi-stationary mid-level feature
will create locally heavy rainfall for Kauai and Oahu--and
maintain a sultry...more humid weather pattern over the entire
region.

Vojtesak