Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
705 AM EST Mon Jan 02 2017

Valid 00Z Tue Jan 03 2017 - 00Z Tue Jan 10 2017

The models show a 500 mb trough gradually amplifying as it crosses
the islands mid week and moves east of the islands later in the
week.  A few secondary low level troughs in the 850-700 mb layer
may pass through and focus widelys cattered to scattered showers.

An upstream mid level ridge approaches from the west over the
weekend, which is then forecast by the models/ensemble means to
deamplify as it arrives over next weekend into early next week. 
Late in the weekend to early next week could see a minimum in
shower coverage with the ridge approaching/arriving plus weak low
level trades.

The models and ensembles are mostly in agreement on the large
scale pattern.  The one exception is the models forecast a weak
frontal wave in the western Pacific along a large scale frontal
zone northwest of the islands late in the week, weakening the low
pressure over the weekend.  The operational ecmwf forecasts the
low to persist longer, with the low at 26n 161w 00z Sunday coming
into the mean ridge position of the ecmwf ensemble mean and other
models/means as well.  Consequently, confidence is low in the
ecmwf with this feature.

Petersen