Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
830 AM EDT Thu Sep 20 2018

Valid 00Z Fri Sep 21 2018 - 00Z Fri Sep 28 2018

The latest models and ensembles reasonably agree that upper
ridging will spread gradually westward over the state underneath a
pair of closed lows developing to the northwest and then northeast
of Hawaii this week. Moisture will become more limited after today
so expect generally fair conditions with modest trades and light
mauka/windward showers to then persist into early next week. By
next Tuesday/Wednesday, the upper low to the northeast is forecast
to weaken, but additional energy digging to the lee of western
Pacific upper ridging is now expected to more ernestly dig into a
reinforcing trough/closed low position to the northwest of the
state. Increased amplitude trends as best depicted by the 00 UTC
ECMWF may be favored given high ampltide of the upstream ridge in
most guidance. This may set the stage for deeper return moisture
response from the tropics into the islands next midweek and an
associated development of an enhanced potential for heavier
showers.

Schichtel