Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
342 AM EDT Wed Sep 09 2020

Valid 00Z Thu Sep 10 2020 - 00Z Thu Sep 17 2020

Today's guidance offers little change in the established trade
pattern that will feature some oscillation of wind speeds along
with windward/mountain focus for generally light shower activity. 
Periods of lighter trades could allow for some sea/land breeze
influence at times.  The majority cluster continues to show an
extended period of below-climatology moisture levels with
precipitable water values tending to be around 1.25 inches or
less.  The 00Z ECMWF brings a narrow band of greater moisture
across the main islands around late Monday-Tuesday but this band
does not show up in the 00Z GFS/GEFS mean or 12Z/08 ECMWF mean. 
Models and means are consistent with the forecast variability in
trades--strengthening somewhat Wednesday into early Fri as high
pressure builds to the north, followed by a weaker trend into the
weekend as the high weakens, and finally modest strengthening
early next weak as the high slowly rebuilds.  There is still
increasing uncertainty in exactly how the surface high will evolve
by next Tuesday-Wednesday due to low-predictability aspects of the
upper pattern to the north of the state.    

Rausch