Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
821 AM EDT Fri Apr 10 2015

Valid 00Z Sat Apr 11 2015 - 00Z Sat Apr 18 2015

The 10/00Z ECENS, GEFS and NAEFS did not offer many changes in the
Subtropical Pacific---though the mid-latitude forecasts are
changing between the Gulf of Alaska and Labrador. The means have
sped up the west-to-east progression of the two primary
mid-latitude Pacific waves---at 125W and 165W respectively at day
4 (Tuesday) Between 14/12Z and 16/12Z, a deep surface cyclone
invof 50N 160W makes a northeastward turn towards the Gulf of
Alaska and shortwave ridging builds across the Subtropics. The
differences in surface high position and strength---between the
deterministic 10/00Z ECMWF and 10/00Z-10/06Z GFS---are
significant, and would suggest using and blend of the 10/00z
ECENS/GEFS for day 5-7, to counter-balance the adjustments of the
10/00Z forecast cycle.

For Hawai'i, the weather forecast will not change much from the
previous one. A split-flow pattern aloft will occasional produce
some high clouds and the best prospects in the medium range period
(days 3-5) for a phasing of the split flow remains near 30N
latitude---but does not pose a forecast issue for the Islands.
Otherwise, persistence seems to be the likely outcome with little
change from the current trade wind regime.

Vojtesak