Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
358 AM EDT Mon Jul 19 2021

Valid 00Z Tue Jul 20 2021 - 00Z Tue Jul 27 2021

Latest guidance continues to show brisk trades supported by high
pressure to the north/northwest of the state.  Strongest winds are
likely to be early in the week.  An upper ridge passing over the
area should keep windward/mountain-focused showers on the lighter
side of the spectrum through midweek.  Then moisture from Felicia
and Guillermo may serve to enhance rainfall over some areas. 
Consensus and continuity are still good with the core of Felicia's
moisture passing to the south of the state Thursday-Friday while
the northern periphery of the moisture shield brushes the Big
Island and vicinity.  Then moisture from Guillermo should reach
the state around Sunday-Monday, though still with a lot of
uncertainty for specifics.  GFS/GEFS runs have been consistent
thus far in tracking the greatest deep moisture to the north of
the islands while some increased moisture extends to the south. 
The UKMET through the end of its run suggests the same while
recent CMC runs have tilted in this direction.  On the other hand
the ECMWF/ECMWF mean bring the highest precipitable water values
farther south, into the state.  Since 24 hours ago the ECMWF has
trended slower to align better with the GFS cluster for timing,
while the ECMWF/ECMWF mean have nudged a little northward. 
Combining continuity and trends for all the guidance, the most
likely scenario appears to lean somewhat more than halfway in the
GFS direction.  An accompanying surface trough could also provide
a temporary weakening of the trades late in the period.     

Rausch