Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
255 AM EST Mon Nov 28 2022

Valid 00Z Tue Nov 29 2022 - 00Z Tue Dec 06 2022

Abundant tropical moisture and shortwave energy aloft will likely
promote some areas of locally heavy rainfall early this week.  The
initial band of moisture/energy may favor the best focus over
central/western areas but another pocket of moisture/upper support
could enhance rainfall a bit over the Big Island into Tuesday. 
Winds should be southeasterly on average, with some variability
that could tilt them more southerly at times.  After early
Wednesday, the latest guidance has finally come closer together
for some details of the forecast.  Consensus now shows an upper
ridge sharpening along or just west of 160W longitude
Wednesday-Thursday and then drifting eastward as it flattens ahead
of general troughing (but less amplified than a number of prior
GFS/GEFS runs).  Meanwhile enough of a surface gradient develops
to support light to moderate trades after midweek.  Precipitable
water values still exhibit some spread but now share a more common
shape/evolution.  The new majority scenario (including the 00Z
GEFS/12Z ECMWF means) has PWATs remaining above climatology for
most of the period but with some southwestward suppression of
highest values.  The 00Z GFS keeps more of the deep moisture over
the islands, while the 00Z ECMWF trends a little drier than other
solutions (as has been the case in recent days).  The ensemble
means provide a good intermediate solution at this time.  Best
potential for lingering moisture/rainfall enhancement should be
over the western islands as a front approaches from the west
during the weekend.  Trailing high pressure could begin to
strengthen the trades next Monday, with current preference between
the GFS (faster timing and strongest winds) and ECMWF (slowest
timing and lightest winds) extremes.

Rausch