Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
351 AM EDT Thu Jun 17 2021

Valid 00Z Fri Jun 18 2021 - 00Z Fri Jun 25 2021

Today's guidance continues to show periodic variation in trades
depending on the southwest extent of eastern Pacific high
pressure.  Winds should trend lighter late week into the weekend,
strengthen into early next week, and finally trend weaker again
Wednesday-Thursday as a front approaches from the west.  Trade
flow will tend to provide greater shower focus to
windward/mountain areas but other locations may see rain at times
as well, especially when lighter trade flow allows for sea/land
breeze influence.  Between now and Saturday an upper low close to
the northern islands should deepen as it drifts a bit eastward. 
This low, which may serve to enhance rainfall somewhat, will
persist into Sunday and then an upper ridge building into the area
from the east will push it northward.  Models/ensembles suggest
this ridge will weaken by Thursday.  Modestly above normal
precipitable water values late this week will likely settle to
near or slightly below normal by the weekend.  Around Tuesday the
GFS/GEFS and ECMWF/ECMWF mean differ over an area of enhanced
moisture passing by to the south, with the latter pair showing a
greater northward extent.  At this time would recommend a
intermediate solution to resolve the difference.   

Rausch