Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
820 AM EDT Thu Oct 05 2017

Valid 00Z Fri Oct 06 2017 - 00Z Fri Oct 13 2017

The very strong upper high (>6000m 500mb heights) to the NNW of
the area (near 40N/165W) and a digging upper low to its east will
rotate around each other to the northeast of Hawai'i tomorrow into
this weekend. This will drive a cold front into the islands Friday
into Saturday and will likely stall across the 50th state as the
upper low completes its anticyclonic loop north of 30N and east of
155W by late Sunday into Monday. Strong trades in the short term
will ease with the passage of the cold front as the winds back
from ENE to NE and NNE but then become more variable this weekend
and may veer back to the SE over the Big Island as the front
weakens and lifts north again. Generally light to locally modest
showers are expected near the front.

Next week, heights will build as the upper low lifts northeastward
into the main westerlies Mon-Tue but then lower again as the
ensembles show upper ridging building west of 170W. This may allow
a weakness to form just west of Hawai'i though the 00Z ECMWF
represented a rather strong solution compared to the ensembles.
However, both the ECMWF and GFS show the possibility of increased
moisture to the area later next week in line with the ensembles,
suggesting more scattered showers for the region.


Fracasso