Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
341 AM EDT Tue Apr 06 2021

Valid 00Z Wed Apr 07 2021 - 00Z Wed Apr 14 2021

Guidance maintains decent agreement and continuity with the
forecast through the weekend.  Flow aloft between an upper low to
the northeast and a ridge to the west will support well below
normal precipitable water values into late week, followed by a
moderate increase (though perhaps only toward climatology) during
the weekend as shortwave energy drops down toward the state from
the northwest.  Meanwhile trades will be fairly strong initially
but then trend lighter with time as mid-latitude high pressure
progresses eastward and the approaching energy aloft this weekend
lowers surface pressures over the area.  Generally
windward-focused rainfall should be on the light side, possibly
increasing a bit during the weekend given the shortwave energy and
moderate increase in moisture.  Thus far guidance has not been
enthusiastic about any meaningful increase in totals during the
weekend though.

By next Monday-Tuesday the primary guidance trend over the past
day has been to maintain greater dominance of the upper low to the
northeast of the state, instead of the weekend shortwave energy
possibly forming its own closed low.  In the latest 00Z suite, the
CMC pulls its upper low center closer to the islands than other
guidance (including its ensemble mean).  Remaining consensus
indicates that continued progression of the overall trough axis
will promote another drying trend early next week.  Light to
moderate trades are likely to continue into early next week. 
Central Pacific high pressure could begin to strengthen trades by
late Tuesday or soon thereafter.   

Rausch