Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
647 AM EST Thu Dec 25 2014

Valid 00Z Fri Dec 26 2014 - 00Z Fri Jan 02 2015

The 25/00Z ECENS/GEFS and their deterministic solutions looked to
be in very good agreement through day 5 (31/00Z)---considering the
complexity of the pattern in the north central Pacific. The
surface front responsible for the unusually cool/wet sensible
weather pattern migrates northeastward during the next 12-24
hours---but the upper-level circulation migrates northward along
155W and maintains weak troughing and a northwest flow aloft into
the weekend.

The deterministic 25/00Z ECMWF is the aggressive/pessimistic
solution after 48 hours---maintaining another cutoff low at 500mb
invof 35N 156W. This system is replaced by---yet another
mid-latitude trough---migrating across the Dateline on Sunday and
reaching 155W next Wednesday.

For the day 5-7...the 25/00z GEFS mean resembles the ECENS
mean---but as is its bias---is the slightly faster solution.
Recommend an ECENS mean (2/3rds) and deterministic ECMWF blend
(1/3rd) through day 7. This should capture the key synoptic-scale
features in the Subtropical Pacific---and the sequencing of the
mid-level impulses embedded with the flow.

Vojtesak