Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
250 AM EST Mon Dec 25 2023

Valid 00Z Tue Dec 26 2023 - 00Z Tue Jan 02 2024

Themes persisting from yesterday include showers staying on the
light side due to precipitable water values staying below
climatology, and a progression of fronts that will likely lead to
variability in winds and shower focus.  Guidance has maintained
reasonable agreement and continuity with a leading front settling
over the state early in the week and then dissipating, with the
associated modest moisture band likely ending up over the central
islands and/or Big Island.  However models/ensemble means continue
to differ for the next couple fronts.  For the front reaching the
area by Friday, the spread ranges from the GFS on the south side
to the 00Z GEFS/12Z ECens mean that are somewhat farther north and
00Z ECMWF near the middle.  Guidance variability up to this point
and GFS inconsistency (some runs straying to the south extreme of
the envelope) seem to favor a middle ground closest to the ECMWF. 
Then with the next front affecting the area by the weekend, the
GFS and to a large degree the GEFS mean as well are deeper than
other guidance with the supporting upper trough and thus push the
front farthest south.  The 00Z ECMWF looks more reasonable for
this front as well, eventually reaching into the main islands but
not pushing south like the GFS/GEFS.  The 12Z ECens mean is a tad
farther north and the 00Z CMC is the northern extreme. 
Interestingly, guidance actually shows less than the expected
spread for the next front approaching from the northwest late
Sunday into Monday/New Year's Day and a general compromise would
be a good starting point for this front that may bring a modest
increase of moisture into the northwestern islands.

Rausch