Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
305 AM EST Fri Feb 07 2020

Valid 00Z Sat Feb 08 2020 - 00Z Sat Feb 15 2020

Guidance agrees fairly well into the weekend, showing an elongated
upper low to the north bringing a trough axis through the main
islands Friday-Friday night and then continuing northeastward
thereafter--helping to push the leading cold front farther away
from the state.  Behind this front expect a period of brisk to
strong northerly winds and mostly light windward-focused
precipitation.  Rapidly amplifying upstream trough energy should
reach the area Sunday.

Guidance disagreement starts with the precise amplitude of this
Sunday trough, ultimately leading to significant position
differences for the upper low that all guidance closes off to the
northeast of the area by Monday.  Comparing the full array of
guidance, the 18Z/00Z GFS runs are on the northeast side of the
envelope while the 00Z ECMWF/CMC and 12Z ECMWF mean are in the
southwest half of the spread.  The 00Z GEFS/CMC means are near the
middle of the spread before drifting a bit closer to the GFS. 
Given the fairly low predictability of such a relatively compact
feature, preference follows a conservative approach--an average
among the non-GFS models and the three ensemble means.  This would
bring the upper low center close to the Big Island for a time
mid-late week as the feature drifts south/southwest, with an
associated surface low also tracking near or over the eastern
islands.  This scenario would bring a period of enhanced winds and
precipitation to some areas.

Late in the week models/means suggest a slow trend toward some
degree of trade flow but with the potential for it to be delayed
by lingering surface troughing.  The easterly flow would bring a
gradual return of some of the moisture being pushed to the east of
the area late this week/weekend.  

Rausch