Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
347 AM EDT Thu Oct 14 2021

Valid 00Z Fri Oct 15 2021 - 00Z Fri Oct 22 2021

Most of today's models and ensembles provide reasonable agreement
and continuity for the overall pattern during the next seven days.
 Expect trades to trend lighter with time as one mid-latitude
front late this week and then a second front reaching farther
south close to the islands by next Wednesday-Thursday weaken
surface ridging north of the state.  Consensus shows precipitable
water values settling to below climatology through a majority of
the period, likely keeping windward-favored showers on the lighter
half of the spectrum.  Guidance continues to show a weak elongated
upper trough/shear axis developing over or just north of the state
between now and the weekend.  From Monday onward solutions offer
varied ideas for how energy aloft may evolve, in essence a
question of how much energy pulls off to the west-southwest versus
what may eventually continue to the east/southeast.  Relative to
other guidance the 00Z GFS seems to be in the considerable
minority with its development of an upper low that tracks eastward
over the main islands Tuesday-Wednesday.  Thus would recommend
leaning toward consensus whose upper flow remains more open and
thus keeping precipitable water values a little lower.  Still the
lingering upper weakness could provide a little modest enhancement
to rainfall at times.  Sufficient weakening of the trades as well
as moisture along the front approaching from the north could alter
the focus/distribution of rainfall from the typical trade pattern
by Wednesday-Thursday.

Rausch