Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
248 AM EST Thu Mar 04 2021

Valid 00Z Fri Mar 05 2021 - 00Z Fri Mar 12 2021

Guidance agrees on the trend toward a wetter pattern after the
forecast starts with below average precipitable water values and
relatively modest windward/mountain focused showers.  The first
step up in moisture will be with the arrival of shortwave energy
and remains of a front from the north, along with a surface trough
drifting westward across the state.  Recent consensus had been
favoring the western islands for best rainfall focus but the
relative emphasis appears to be less agreeable now.  Models and
means display a more pronounced increase of moisture from the
southeast after the weekend.  Over the past day there has been a
notable trend toward highest precipitable water values extending
farther northwestward across the state, while typical spread
persists for timing of this moisture surge and magnitude (00Z
GFS/ECMWF reaching up to at least 1.75 inches at some locations,
00Z GEFS/12Z ECMWF means a little lower).  Although the late week
into weekend upper trough will gradually weaken, one or more
impulses may remain over or near the state for much of next week
and help to enhance rainfall at times.  Expect trades to weaken a
bit into late this week, followed by a return to stronger winds
from the weekend into next week as high pressure settles to the
north and then northeast of the state.    

Rausch