Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
334 AM EDT Thu Aug 10 2023

Valid 00Z Fri Aug 11 2023 - 00Z Fri Aug 18 2023

Latest guidance agrees upon a rather dry pattern at least into
early next week as the state remains under an east-west axis of
below average precipitable water values.  Initially brisk trades,
focusing what showers there are over windward/mountain terrain,
should trend toward moderate levels with an upper weakness
dropping down from the north-northeast during the weekend helping
to loosen the surface pressure gradient.  Models/ensemble means
are suggesting this weakness should consist of a leading upper low
that departs to the west of the islands after Monday while a
lingering low to the northeast of the state early in the week
drifts westward through Thursday.  A lot of spread develops for
westward progression of this second low.  By early Thursday the
00Z CMC is farthest east, the 00Z GFS/GEFS mean/CMC mean north of
the state, the 12Z ECMWF mean a little farther west, and the 00Z
ECMWF more west.  These differences appear to have minimal
influence on the trades which by Tuesday-Thursday should be near
or slightly stronger than prior days, but may affect moisture
details within a general theme of somewhat higher amounts reaching
the Big Island and vicinity during that time.  Overall preference
is for an average solution for the upper feature and day-to-day
moisture late in the forecast period.

Rausch