Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
827 AM EDT Sat Oct 18 2014
Valid 00Z Sun Oct 19 2014 - 00Z Sun Oct 26 2014
...'Ana' remains a significant feature in the Tropics...
With focus on 'Ana' in the shorter-term forecast, please refer to
the Honolulu forecast office and Central Pacific Hurricane Center
for the better details surrounding this tropical system and its
direct impacts on Hawai'i.
The 18/00Z ECENS/GEFS ensembles and their deterministic runs
remain on divergent paths in the medium range portion of the
forecast---between 160W-170W longitude.
As trends go, the GEFS/GFS have maintained a consistent approach
and the re-curvature 'theme' for the good part of a week's worth
of forecasts. Meanwhile, the ECENS/ECMWF solutions trend
west-northwestward and produce a 'delayed' timing of the poleward
drift of the system. These two 'camps' provide the 'left and
right' edges of the track envelope.
To give one a perspective---
The 18/00Z Canadian solution is disconcerting---not that it
supports the ECMWF deterministic solution---but that it maintains
an intensity similar to the deterministic 18/00Z GFS (at 24/12Z).
And the difference in longitude between the Canadian and GFS at
that time step---is a good 10 degrees apart. For day 6-7, the
operational runs generates a tropical wave/system along 140W by
day 6 and the Canadian is the 'most developed' of the 00Z guidance
The forecast challenge in the medium range becomes one of
'ensemble' choices for the outcome of 'wavelength amplitude' in
the eastern half of the Pacific---along 140W by day 7. Recommend
leaning on the ECENS for what eventually 'shakes out' in the
eastern Pacific and with the day 5-7 forecast in the Subtropical