Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
807 AM EDT Thu May 14 2015

Valid 00Z Fri May 15 2015 - 00Z Fri May 22 2015

Nothing observed in the 14/00Z guidance cycle deviates from the
current Hawai'i forecast philosophy. In general---persistent
temp/pop-QPF forecasts through day 7.  

The bulk of the model differences are observed at mid-latitude and
near the end of the medium range forecast period---as remnant
tropical southwest Pacific energy entrains into the westerlies
along 50N latitude. Around day 6 (20/12Z)---initial mid-level
energy crosses 170W longitude and begins to carve out a longwave
trough southward to 40N latitude.

The 14/00Z ECENS/NAEFS and GEFS support the continued emergence of
the longwave and hint that this longwave will gain amplitude by
day 7 (21/12z)---with the 14/00Z deterministic ECMWF and GFS
generating a surface cyclone along the base of this projected
longwave 500mb trough.

For now, recommend a blend of the 14/00Z ECENS/NAEFS for the day
6-7 to capture the mass field pattern across the northern
Pacific---in advance of this emerging (amplified) pattern.

Vojtesak