The Weather Prediction Center

College Park, MD

Hawaii Extended Forecast Discussion

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
818 AM EDT Thu Jul 31 2014

Valid 00Z Fri Aug 01 2014 - 00Z Fri Aug 08 2014

The 31/00Z ECENS and GEFS means and their deterministic runs
maintained decent continuity through 6/12z---with a trend for more
eastward progression of a moderate/stronger shortwave through the
Alaska panhandle.

The northeastward migration of a closed h5-to-sfc low through the
central gulf of Alaska into day 5-6 has taken a slight
twist...with the 31/00Z GFS deterministic taking the system into
northern British Columbia at a faster pace than the deterministic
ECMWF by the end of day 7. From a continuity perspective, thought
the GFS has been a better indicator of medium range surface
features in the Gulf of Alaska vs the ECMWF.

In the Subtropics, the 31/00Z GEFS/ECENS means and their
deterministic runs do not waver much at all with the surface ridge
strength and central pressure location invof 35-40N 140W between
days 4-6. What will be a key feature emerging in the latter half
of the medium range in the eastern Gulf of Alaska appears to have
a significant impact on the subtropical ridge axis and northward
transport of tropical moisture from the deep Tropics.

Blending the 31/00Z GFS/ECMWF deterministic runs continues to
indicate a disturbance invof ~146W @ 7/00Z and ~149W @ 7/12Z---the
late day 6-early day 7 time frame. This blend yields a slightly
slower trend versus 24 hours ago---and the 30/00Z cycle. But a 1
degree eastward adjustment is not a bad starting point for a
feature that has also trended a degree or two north and west in
the last 24 hours.

Please monitor information from the Central Pacific Hurricane
Center and National Hurricane Center concerning tropical weather
developments impacting Hawai'i.


Last Updated: 818 AM EDT Thu Jul 31 2014