Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
813 AM EDT Thu Jul 20 2017

Valid 00Z Fri Jul 21 2017 - 00Z Fri Jul 28 2017

A couple features of note will affect Hawai'i over the next week.
Tropical Storm Fernanda, currently about 1000 miles east of
Hawai'i per the latest NHC advisory, is forecast to quickly weaken
over the next couple days as it continues moving
west-northwestward. A remnant low associated with this system is
forecast to pass north of the Islands early next week. As the
remnant low passes north of Hawai'i, a brief disruption to the
easterly trades is possible, but the trades should quickly resume
as the system passes by. An increase in precipitable water values
ahead of the system may also increase shower activity by Sunday
and Monday, although the core of deeper moisture associated with
the system is forecast by the GFS and the ECMWF to remain north of
the Islands.

Otherwise, an expansive surface high is forecast by all guidance
to remain anchored well northeast of Hawai'i through the next
week, which should keep 10-15 kt surface easterlies prevalent
across the Islands with the typical associated shower activity.


Ryan