Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
340 AM EDT Tue May 12 2026

Valid 00Z Wed 13 May 2026 - 00Z Wed 20 May 2026

A stable synoptic pattern is expected to persist through the
upcoming forecast period, highlighted by robust surface ridging
north of the state. At the start of period, deep ridging will
support fresh easterly trade wind flow across the island chain.
Surface high pressure is expected to gradually shift east mid to 
late week, though easterly flow will prevail across the state into
early next week. In the upper levels, the high will also shift 
east, resulting in a developing weakness in the ridge across the 
state. A weak upper level low is forecast to drops south into 
islands late in the week and linger into the weekend before 
drifting east early next week. While the overall surface pattern 
remains stable, this feature may provide enough mid-level cooling 
to weaken the trade wind inversion and help organize or enhance 
passing showers. Otherwise, precipitation will be mostly characterized
by light passing showers embedded in the trades and focused 
along the windward slopes and mauka areas.

Pereira