Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
822 AM EDT Wed May 16 2018

Valid 00Z Thu May 17 2018 - 00Z Thu May 24 2018

The majority of model/ensemble guidance show Hawaii remaining in a
relatively benign weather pattern over the next seven days, with
gradually rising 500mb heights and increasing ENE trades by the
weekend owing to the subtropical ridge becoming firmly established
near 30 degrees north.  By the beginning of next week, the
ensemble means agree that a large surface low will track eastward
across the northern Pacific, with a trailing cold front breaking
down the aforementioned ridge slightly.  At this time, the EC mean
is slightly faster with the progression of this trough axis
compared to the GEFS mean, but remain similar in the immediate
vicinity of the state.  A solution more weighted towards the EC
mean along with some of the GEFS means appears best with respect
to the trough evolution across the north central Pacific next week.

In terms of sensible weather, trades should remain lighter than
usual through early Thursday owing to the weaker surface pressure
gradient and a surface trough north of Hawaii.  By later in the
week as the subtropical ridge expands to the north, east to
northeast trades should increase into the 15-25 mph range, and
likely continuing into early next week.  Moisture will be rather
limited in this pattern, and thus isolated to scattered windward
showers with no anomalous moisture surges expected.

D. Hamrick