Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
811 AM EDT Mon Jul 24 2017

Valid 00Z Tue Jul 25 2017 - 00Z Tue Aug 01 2017

The remnants of Tropical Storm Fernanda are passing just north of
Hawai'i this morning per latest satellite imagery. The system is
expected to continue its path westward, moving away from the
western Islands by this evening. In the wake of the system, 10-20
kt easterly trades should quickly resume as strong high pressure
is anchored over the north central Pacific. High pressure is
forecast by all guidance to remain in place north of Hawai'i
through the next week. Meanwhile, Tropical Storm Greg is forecast
by the NHC to continue a gradual weakening as it moves
west-northwestward before becoming post-tropical and making a
west-southwestward turn by Wednesday night. Model spread has
reduced compared to this time yesterday, and the majority of
deterministic guidance now continue the remnant low on this
west-southwestward track, keeping the system well south of Hawai'i
- likely due to consensus on a somewhat stronger mid/upper level
ridge persisting along 30 N in the eastern Pacific. The
implications of this for Hawai'i will be 10-20 kt E-ENE low-level
flow persisting into early next week, and perhaps a reduction in
shower activity as drier air originating in the subtropical ridge
is wrapped southward toward Greg's remnant circulation by Sunday.


Ryan