Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
809 AM EDT Fri May 15 2015

Valid 00Z Sat May 16 2015 - 00Z Sat May 23 2015

The 15/00Z model guidance (EC, GFS, Canadian) offered a few new
wrinkles in the north central and equatorial Pacific.

In the north central Pacific--- based on the changes in
initialization, path and infusion of remnant tropical southwest
Pacific typhoon energy ('Dolphin')---late in this forecast
period---the guidance begins to take on a large spread between
160W-175W with the longwave trough axis and degree of amplitude
downstream in the Gulf of Alaska. Here, the GEFS mean and
deterministic GFS become extreme solutions at mid latitude and a
much quicker solution along 160W and eastward to 130W along 45N
latitude by day 6-7. A blend of the 15/00Z ECENS/NAEFS continues
to be a decent solution for the mass field forecast for the
mid-latitude Pacific.

A second subtle wrinkle is embedded within a weak equatorial
trough holding a mid-level disturbance near 8N 170E. To its
immediate north, weak upper-level troughing is handled by the
three means adequately---and may allow some westerly flow and
mid-level moisture to streak across Hawai'i between the day 2 and
day 4 time frame. This does not look to be an appreciably active
sensible weather period---but worth noting the new variation seen
in the 15/00Z forecast cycle.

Again today, recommend a blend of the 15/00Z ECENS/NAEFS for the
day 5-7 period to capture the mass field changes emerging across
the northern Pacific---and in advance of this emerging (amplified)
pattern north and northeast of Hawai'i.

Vojtesak