Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
814 AM EDT Sat Jul 14 2018

Valid 00Z Sun Jul 15 2018 - 00Z Sun Jul 22 2018

The models and the ensemble means are in good agreement in
portraying two strong, low level high pressure areas centered
roughly near 40 degrees north through this forecast period.  A col
is created within this ridge from a cold front crossing the
Aleutians and the north Pacific this weekend into Monday while
passing well to the north of the Hawaii domain.  At the mid
levels, an elongated upper level tropospheric trough centered just
north of the Islands this weekend is forecast to move west of the
state by the middle of the week, with an associated inverted
surface trough.  There should be a weak upper level ridge building
in from the east by the middle to end of next week.  The EC mean
is slightly faster with the westward progression of the trough
compared to the GEFS mean.

Precipitable water values will briefly be above normal due to the
mid/upper level trough interacting with a weak easterly wave this
weekend, thus increasing shower and thunderstorm chances.  Another
surge of deep moisture in association with a second easterly wave
is expected to pass just south of the Big Island by Thursday, and
this has been indicated in the model guidance for several days,
with drier conditions following behind it.  However, the greatest
concentration of convection is expected to remain over the open
waters of the central Pacific.

D. Hamrick