Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
440 AM EDT Sat Apr 11 2026

Valid 00Z Sun 12 Apr 2026 - 00Z Sun 19 Apr 2026

...Periods of Heavy Rainfall Expected Across the Islands this 
Weekend into early next week...

The closed upper low currently situated approximately 1000 to 1100
miles to the northwest of the Islands near 36N 167W, will remain 
nearly stationary through late Monday, and then only begin to push
slowly eastward Tuesday and Wednesday. There is no change to
prior model consensus of mid to upper level southwesterly to west
southwesterly flow aloft remaining established across the 
islands, on the southeast side of this nearly stationary closed 
low. This will allow and axis of much above average PW values, 2 
to 4+ standard deviations above the mean to persist across the 
Island chain through this weekend and into much of next week.

Shortwaves in this persistent southwest mid to upper level flow 
will continue to enhance large scale uvvs in the anomalous PW 
axis, supporting rounds of heavy rainfall and an elevated risk of 
life threatening flash flooding and mudslides/debris flows this 
weekend and possibly for portions of the upcoming week.   While 
the anomalous PW axis is expected to remain across the Islands 
through much of the upcoming week, models continue to be more 
emphatic about heavy rain chances through the weekend and Monday
for the western to central portion of the state. After this, 
model qpf is not as focused, but locally heavy rains are still 
possible given the much above average PW values remaining across 
the state and potential for additional shortwaves in the above
mentioned west southwesterly to southwesterly mid to upper level
flow.  

Through the forecast period, the typical trade wind pattern will
remain disrupted. A return to a more normal trade pattern may
occur late in the upcoming week.

Oravec