Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
359 AM EDT Sun Apr 07 2024

Valid 00Z Mon Apr 08 2024 - 00Z Mon Apr 15 2024

Models and ensembles remain consistent for the forecast from the
weekend into the first half of next week, and have finally come
into better agreement with the forecast evolution during the
latter half of the week. There are still some finer details to be
resolved in the late week/weekend time frame though.  Expect
trades to continue trending somewhat lighter early this week as
high pressure initially north of the state weakens and tracks into
the eastern Pacific.  A front approaching from the northwest by
midweek should then turn winds more southeasterly. 
Windward-focused showers, with a few possibly straying to leeward
areas, should be moderate as a weakness aloft persisting into
early Tuesday could enhance amounts but guidance shows
precipitable water values staying somewhat below normal into the
early part of the week.  By Wednesday-Thursday, guidance
clustering has dramatically improved versus previous days, showing
a deep upper low closing off to the northwest of the state.  The
upper low will most likely drift northward and open up from Friday
onward as upstream energy filters into the overall trough.  Based
on the current consensus, the front extending south from the
associated surface low should get close to the western islands and
serve as a focus for heavy rainfall over that part of the state,
within a broader pattern of southerly moisture flow that will
likely bring precipitable water values above 1.5 inches across the
area for multiple days.  Of course exact details will take
additional time to resolve.  Although the CMC from a couple days
ago led the trend for where the upper low appears destined to
close off, today's 00Z CMC strays to the amplified/eastern side
with the larger scale upper trough by next weekend, pushing the
surface front farther east than most other guidance including
recent ECMWF-initialized machine learning models.  Thus would
recommend a composite of the GFS/ECMWF and their ensemble means as
a starting point for the forecast.

Rausch