Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
811 AM EDT Sat Sep 09 2017

Valid 00Z Sun Sep 10 2017 - 00Z Sun Sep 17 2017

Expect trades to weaken going into early next week as the
southwestern periphery of eastern Pacific high pressure recedes
and a mid-latitude front pushes southward, likely stalling to the
north of the islands.  This front will be supported by an upper
trough (and possible embedded low) which according to latest
guidance should reach its greatest southward position by late
Tuesday-Wednesday.  By late in the week the front should weaken as
upper support lifts out, allowing for a return of moderate trade
flow by next Friday-Saturday.  Among latest models/ensemble means,
the 00z GEFS mean/UKMET side with the 00z ECMWF/ECMWF mean in
lifting out the upper feature a little slower than the 00z-06z
GFS/00z CMC runs.  Thus would lean slightly toward the slower
scenario for this part of the forecast.

Shower activity will likely have somewhat more land/sea breeze
influence over the next few days with the weakening of the trades.
 Then rainfall should regain a windward focus as trades become
established again late week into the weekend.  The Big Island and
vicinity should see highest precipitable water values into early
next week with a tendency toward near to slightly below normal
values over most of the state for the rest of the period.

Rausch