Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
729 AM EST Sat Jan 31 2015

Valid 00Z Sun Feb 01 2015 - 00Z Sun Feb 08 2015

The 31/00Z ECENS/GEFS means and deterministic runs have not
wavered on their depiction of the synoptic-scale pattern through
f84 (3/12Z)---and the emergence of a deepening surface cyclone
invof ~30N 155W (a sub 996mb sfc low).


Medium Range Assessment/Uncertainty...
Fundamentally,the ECENS/GEFS differ significantly after 5/12Z
(mid-point day 5) as the day 3---30N 155W surface cyclone
intensifies and migrates downwind of the upper-level trough. the
fundamental difference is---erosion and breakdown of the
downstream North American ridge. For reasons of semi-unknown
origin...the 31/00Z GEFS/GFS deflects the deep cyclone (now a sub
968 mb low) by 5/12Z so far away from the Gulf of Alaska and the
upper-level ridge---to rule out the entire package.

Recommend settling on the more consistent ECENS and deterministic
ECMWF (last three runs) during this 1-7day forecast cycle. Its
suggestion that a rather broad and fast-moving 200mb westerly jet
will become well-established across the western Pacific---and
covering the 35N-40N latitudes to roughly 150W-160W. That flow
should anchor a series of moderately-intense surface waves north
and west of Hawai'i through the period. The sequencing and
evolution---handled with better success.

Vojtesak