Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
344 AM EDT Fri Apr 12 2024

Valid 00Z Sat Apr 13 2024 - 00Z Sat Apr 20 2024

...Heavy rainfall threat over the western islands late this week...

A deep upper low and surface system currently posititioned
northwest of Hawaii will eventually open up as it lifts
northeastward this weekend. Ongoing heavy rainfall across mainly
Kauai and Oahu will continue today/Friday with abundant deep
moisture and precipitable water values surging beyond three
standard deviations above normal. The guidance continues to
suggest a break around Saturday as the front drifts back to the
west a bit, and then a return of enhanced rainfall to the western
and possibly central parts of the main islands as progression of
the remaining upper trough pushes the front eastward later this
weekend/early next week. The front may stall upon reaching either
side of the Big Island after early next week but rainfall should
not be as heavy given less extreme precipitable water values.

By next week, there is increasing uncertainty in the details of a
weaker closed low northeast of the state and any additional
shortwave energy tracking through the state around mid-week.
Regardless, there is consensus that surface high pressure should
again build north of the state, allowing for a return to breezy
easterly trades and showers favoring the typical windward
locations later next week.

Santorelli