Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
245 AM EST Fri Nov 17 2023

Valid 00Z Sat Nov 18 2023 - 00Z Sat Nov 25 2023

Weak high pressure passing by to the north on Friday will support
moderate trades, while windward focused showers should be on the
light side given below climatology precipitable water values. 
Winds will quickly turn more southerly on Saturday ahead of an
approaching cold front.  Guidance loosely agrees on bringing this
front into the islands by Sunday-Monday, but with some spread for
how far southeast the front and its associated band of moisture
and enhanced rainfall reach.  The 00Z GEFS/12Z ECens means both
show the main moisture band reaching into the central islands by
Monday, which is in line with the 18Z GFS and 00Z CMC.  The past
two ECMWF runs are farther northwest and the 00Z GFS farther
southeast.  A compromise approach also looks reasonable based on
forecasts aloft, with the GFS a tad on the amplified side for the
upper trough and the ECMWF pulling off some energy from the
southwest part of the trough (yielding a remaining trough less
amplified than other models and means).

Regardless of exactly where the front settles, expect the front
and its moisture band to dissipate quickly after Monday with
trades becoming established again from Tuesday onward.  Rainfall
totals from showers should generally be on the lighter half of the
spectrum as moisture hovers near or slightly below climatology. 
Winds could trend somewhat lighter and more southeasterly toward
the end of next week as a front approaches from the northwest but
model/ensemble spread keep confidence low for specifics at this
time. 

Rausch