Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
746 AM EDT Fri Sep 12 2014
Valid 00Z Sat Sep 13 2014 - 00Z Sat Sep 20 2014
The 12/00z GFS/ECMWF and their ensembles/means were in much better
agreement through the day 5-6 period (17/12Z-19/00Z) across the
north Pacific. The northward displacement of a surface ridge in
the eastern Pacific is effectively holding down the Northeast
Trades---and through Wednesday---mid-level to upper-level
troughing prevails in the eastern Pacific. After Wednesday,
troughing migrates downstream into the western coast of North
America and the Subtropical Ridge rebuilds along 30N-35N latitude
from the west.
The 12/00Z deterministic GFS/ECMWF have enough of the detail in
the central Pacific to recommend a blend of both into day 6 to
handle the re-emergence of the Subtropical Ridge. Their respective
ensemble means have minimal spread for day 7---aside from off the
coast of Baja California and invof Kodiak Island AK.
For Hawai'i, a persistence forecast is in order---with light
trades, slightly above normal temperatures, and scattered showers.