Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
724 AM EST Thu Nov 07 2019

Valid 00Z Fri Nov 08 2019 - 00Z Fri Nov 15 2019

Late this week expect initial northeasterly trades to trend
lighter as supporting high pressure weakens and settles toward the
main islands.  Then an upper trough passing over/north of the area
will bring in another front this weekend.  The combination of
upper dynamics and associated front/moisture should lead to some
increase of rainfall, perhaps a little more than what recent ECMWF
runs suggest. 

From late weekend into next week high pressure behind the front
will likely bring a return of light-moderate trade flow and more
windward/mountain focus for rainfall.  Amounts should be in the
lighter half of the spectrum.  By this time models and ensembles
diverge for amplitude/progression of the upper trough that passes
east of the area.  GFS/GEFS runs are on the slower/amplified side
of the spread, but the average of 00Z ECMWF ensembles would
suggest the 00Z ECMWF/CMC might become a little too fast.  Thus a
compromise solution looks most reasonable.  Also, consecutive GFS
runs are quite varied in how much moisture lingers over the area
(00Z run much drier than the 06Z run) with the GEFS/ECMWF means
along the 00Z ECMWF clustering the best in depicting 1.25-1.50
inch precipitable water values over the region.  Another
mid-latitude trough will bring a front into the picture to the
distant northwest by next Thursday.  Low level winds may trend
more southeasterly at this time.  GFS runs become more amplified
with the southeast part of the trough by the end of the period and
could be overdone with the northward moisture return.

Rausch