Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
208 AM EST Thu Jan 16 2025

Valid 00Z Fri Jan 17 2025 - 00Z Fri Jan 24 2025

Today's guidance continues to show good agreement and continuity
into early next week, followed by increasing divergence from
Tuesday onward. A front passing through the main islands
Thursday-Friday will disrupt the trades and possibly bring some
pockets of heavier rainfall, though higher totals should remain
well to the north.  High pressure behind this front and a weaker
trailing front to the northwest will likely bring moderate to
brisk northeasterly winds for the weekend into early next week. 
Guidance is consistent in showing below-climatology precipitable
water values behind the late-week front, keeping most showers
fairly light during the weekend and first part of next week.

Today's guidance shows a similar divergence from 24 hours ago
Tuesday onward with an amplifying upper trough and leading cold
front.  Among the standard dynamical guidance, the ECMWF/CMC and
their ensemble means are still slower and more amplified with the
trough versus the latest GFS runs.  The 00Z GEFS mean is somewhat
of a compromise.  At the surface this makes the difference between
a slower/wetter frontal passage on Wednesday in the ECMWF cluster
versus a faster/drier one in the GFS, along with trailing high
pressure restoring trade flow more quickly.  Recent machine
learning models have displayed typical spread, but on average
continue to recommend a compromise solution (which is still
preferred) for the upper trough and frontal progression.  The 00Z
ECMWF run has trended lighter with its QPF along the front versus
previous runs, which is one step toward a compromise even if its
timing is still relatively slow.

Rausch