Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
808 AM EDT Fri Aug 01 2014
Valid 00Z Sat Aug 02 2014 - 00Z Sat Aug 09 2014
The August 1/00Z ECENS and GEFS means and their deterministic runs
maintained decent continuity through 6/12Z (mid-point_day 5)
across a large portion of the northern hemispheric Pacific Ocean.
An active tropical pattern and series of systems off the east
Asian coast between the Marianas and Japan are creating large
spreads in the guidance beyond day 6. The key feature in the
northern Pacific is the mid-level and upper-level long wave trough
invof 155W and it's quasi-stationary positioning along 150W
throughout much of this medium range period--as energy and
moisture off the Japan reloads the trough.
For the Subtropics, the long wave trough extends sufficiently
southward into the Subtropics to produce an appreciable weakness
in the Subtropical Ridge axis invof 25N. In turn, this weakness
appears to directly impact the Islands with more influence from
the Tropics--and an enhancement of the trade wind flow regime.
The 31/00Z GFS/ECMWF deterministic runs initialized 'Iselle' with
the 00Z cycle producing an additionally slower west-northwestward
track west of 140W between 16N (ECMWF solution) and 19N (GFS
solution) for days 6-7.
fyi...looked like the 31/00Z Canadian had a bad run across the
After 6/12z, recommend an equally-weighted blend of the 1/00Z
ECENS, GEFS AND NAEFS means to handle the large spread across the
southern Bering Sea, Gulf of Alaska and with the track of 'Iselle'.
For additional information, please consult/refer to the latest
updates and bulletins from the Central Pacific Hurricane Center
and National Hurricane Center.