Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
725 AM EST Tue Feb 24 2015

Valid 00Z Wed Feb 25 2015 - 00Z Wed Mar 04 2015

The 24/00Z GEFS/GFS, ECENS/ECMWF and Canadian were--- in principle
--- good solutions through much of day 4 (1/00Z)--- in their
depiction of a cutoff 500mb low invof 38N 164W. This allows for a
mid-level trough to make a pass across the western half of the
state--- from northwest to southeast. 

After day 4, the deterministic GFS, Canadian and ECMWF all diverge
with respect to the amplitude of a shortwave mid-level ridge along
140W from the Gulf of Alaska to the Subtropics. Concerning the
'Kona-like' upper system along 15N 140W, the latest guidance
allows the feature to make its closest approach to the Big Island
around 27/12Z, with the mid-level ridge to its north and the
frontal boundary to its west---effectively 'blocking' its westward
migration after 27/12Z.

So for the latter half of this forecast period, recommend a blend
of the 24/00Z GEFS/ECENS/NAEFS. This would make for a slightly
more-amplified flow pattern across the Pacific---but a slower
west-to-east progression of the low-level front across Hawai'i
this weekend.

Vojtesak