Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
804 AM EDT Wed May 20 2015

Valid 00Z Thu May 21 2015 - 00Z Thu May 28 2015

The persistent positive anomaly over western Canada remains
conducive for allowing the upstream westerlies to occasionally
separate into one or more pieces, which is depicted by most of the
current guidance across the northern Pacific by this weekend.  The
separation of the westerlies will result in a small closed low
forming just east of the islands by Saturday, which will support a
weakening of the trades and a weak cold frontal passage.  The
small closed low then becomes reinforced in about the same
location toward the middle of next week.  The effect should be to
sustain a northerly low level wind component through the middle of
next week.  Other than primarily scattered windward showers
through the period, moisture anomalies are generally negative and
too low to support much rainfall.  Almost any model or combination
of models will provide a reasonable starting point for any
forecast, with more of a combination recommended by early next
week, due to the growing spread.

James