Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
204 AM EDT Thu May 14 2020

Valid 00Z Fri May 15 2020 - 00Z Fri May 22 2020

Models/ensembles show good consensus that a mid/upper-level ridge
should remain in place across Hawaii and much of the Central
Pacific through the next week, strengthening through time.
Relatively weak trades are expected into Friday as weak surface
high pressure results in a relatively weak pressure gradient
across the region. As a stronger surface high develops north of
the state once again by the weekend, moderate trades should
gradually return. Ensemble means continue to show good consensus
(ECENS/GEFS/NAEFS) that the upper ridge should strengthen over the
weekend, with means showing the center of the upper ridge anchored
directly over Hawaii Sunday through early next week. The ECMWF and
GFS continue to show consensus that the trailing end of a decaying
frontal boundary should approach Hawaii from the north by Mon-Tue,
with somewhat deeper moisture pooled along the boundary bringing a
some increase in shower activity, but keeping the focus for
showers primarily in favored windward locations. The ECMWF is a
bit more bullish than the GFS with coverage and intensity of
convection in association with the boundary next week,
particularly across the Big Island. Ensemble probabilities suggest
that the threat for heavy rain is low, and this is supported
conceptually by the presence of the upper-level ridge overhead by
that time.

Ryan