Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
403 AM EDT Fri Apr 01 2022

Valid 00Z Sat Apr 02 2022 - 00Z Sat Apr 09 2022

Today's guidance agrees well with the forecast into the early part
of next week.  Strong high pressure to the north of the state will
support brisk trades through the weekend, with showers focused
mainly over windward/mountain areas.  Totals should be in the
light to moderate range given precipitable water values forecast
to be slightly below climatology.  The combination of
opening/progression of an upper low to the west of the islands as
of early Monday and some weaker impulses closer by will likely
draw moisture northward into the state during Monday-Tuesday,
leading to somewhat greater rainfall with the Big Island most
favored.  Trades should slacken as a cold front approaches from
the northwest.  Expect this front to remain northwest of the state
though.

By next Wednesday-Friday the 00Z GFS diverges from most other
guidance for details of an amplifying upper trough northwest of
the state, with corresponding differences in the surface pattern
and rainfall.  The GFS develops the features near 165-170W
longitude and brings additional moisture into the region while
remaining guidance (including the GEFS mean) shows a deeper trough
but one that is farther northwest, generally keeping the moisture
surge west of the main islands through Friday.  The GEFS has some
members that hedge in the GFS direction aloft (though the GFS is
still fairly extreme versus the envelope at some height values) so
the mean shows a decent moisture increase over the state as well. 
However the overall pattern aloft is closer to consensus, albeit
with lower heights southeast of the upper trough axis.  Favoring
the majority cluster would lead to only a limited increase of
moisture/rainfall through Friday.  Trades could rebound a bit as
high pressure passes by to the north, followed by a southeasterly
trend as the high reaches far enough east and the upper trough's
surface reflection comes into the picture to the distant
northwest.        

Rausch