Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
829 AM EDT Mon Oct 08 2018

Valid 00Z Tue Oct 09 2018 - 00Z Tue Oct 16 2018

An upper high near 39N/143W will slowly weaken and move eastward
over the next few days as troughing deepens just to the north of
the region. The moisture axis along an old frontal boundary will
stay just west of the region as drier air slowly pushes in from
the east on slowly backing trades from east to east-northeast.
This supports mainly windward/mauka showers. By late this week the
ensembles diverge in their handling of the trough to the north.
The 00Z ECMWF and its ensembles (along with the 00Z Canadian) were
much deeper/slower with trough than the GFS (and parallel GFS/FV3)
and GEFS members (along with the 00Z UKMET). Prefer a solution
near the 00Z ECMWF ensemble mean which is near the ECMWF but
weaker/quicker given the uncertainty and fairly recent trend. A
slower trough/upper low may bring in moisture on its east side
through the Big Island over the weekend but a farther east/weaken
upper low or open trough would keep any moisture axis east of the
area.

Fracasso