Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
338 AM EDT Thu May 13 2021

Valid 00Z Fri May 14 2021 - 00Z Fri May 21 2021

Latest models and ensemble means continue to agree upon a
persistent trade pattern with below normal precipitable water
values helping to keep primarily windward-focused showers on the
lighter side.  Moderate to brisk trades may tend to be strongest
around late week into the weekend given a slightly tighter surface
pressure gradient in most guidance during that period.  By next
Wednesday-Thursday high pressure should reach fairly far into the
East Pacific but will still extend a ridge well westward and
maintain at least moderate trades.  Meanwhile precipitable water
values should gradually decline into the weekend and early next
week, followed by only a gradual rebound.  Guidance has come into
better agreement that the upper low lingering northeast of the
state through the weekend should lift away during the first part
of the next week (though a bit slower in the 00Z CMC/CMC mean
versus other models/means).  Sunday-Monday remains the time frame
when shortwave energy around the southwest side of the upper low
may reach the islands and increase rainfall to some degree. 
However the lack of significant moisture should make any
enhancement fairly modest.    

Rausch