Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
355 AM EDT Mon Apr 05 2021

Valid 00Z Tue Apr 06 2021 - 00Z Tue Apr 13 2021

Model and ensemble guidance is fairly agreeable and consistent
into the coming weekend.  The state's position between an upper
low to the northeast and a ridge to the west will keep
precipitable water values below climatology for a decent portion
of the week.  Collapse of the ridge and approach of shortwave
energy from the northwest late in the week will likely increase
moisture somewhat by the weekend but perhaps only back to normal
values.  Expect strong trades early this week as mid-latitude high
pressure extends its influence well southward, followed by gradual
weakening as the high progresses eastward and height falls aloft
promote lower surface pressures over the state.  Remains of the
system to the northeast could also approach from the northeast. 
Trade flow will promote primarily windward focus of rainfall that
should be in the lighter half of the spectrum given the expected
moisture levels.  By early next week guidance agrees on mean
troughing aloft over the area but differs on the specifics.  In
particular the 00Z ECMWF brings an upper low center down to the
main islands by late next Monday while remaining guidance suggests
a closed low would be farther north or northeast if it exists. 
While the ECMWF may be a slightly less probable scenario, all
solutions do fall within typical guidance spread/error range for
forecasts that far out in time so a guidance average would be a
reasonable starting point for a specific forecast.  

Rausch