Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
341 AM EDT Fri Aug 19 2022

Valid 00Z Sat Aug 20 2022 - 00Z Sat Aug 27 2022

Today's guidance agrees well for the overall pattern evolution
through the next seven days, though uncertainties exist for one or
more low-predictability upper level impulses that could approach
the islands from the east next week.  From late this week through
the weekend expect fairly light and primarily windward-focused
showers as a surface ridge to the north supports moderate trades
and precipitable water values stay below climatology.  Upper
ridging will prevail as well.  Monday should serve as a transition
into a brief period of lighter winds Tuesday-Wednesday as upper
troughing and surface front north of the state erode the surface
ridge.  In addition consensus shows a band of moisture crossing
the area in this time frame, so expect showers to produce somewhat
higher totals and with some sea/land breeze influence.  With
differences in specifics, by next Thursday-Friday the models and
ensembles show the upper trough relaxing while the eastern Pacific
deep-layer ridge retrogrades somewhat.  This should support a
rebound in trades and a return to more windward/mountain focus for
rainfall.  Most guidance shows a decline in moisture late in the
week but on Friday there is some divergence in solutions, with the
00Z ECMWF bringing in another pocket of greater moisture that most
remaining guidance depicts minimally or not at all.

Rausch