Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
302 AM EST Thu Jan 07 2021

Valid 00Z Fri Jan 08 2021 - 00Z Fri Jan 15 2021

Upper ridging will weaken over the region and build just west of
the Dateline this weekend. Trades will weaken again Friday as the
pressure gradient relaxes well ahead of a front to the north. With
precipitable water values between about 0.8-1.1 inches, light
windward and mountain showers are forecast over the next day or
two. Models and ensembles indicate troughing dipping into the area
Saturday, associated with a surface front that will push into the
area and weaken/dissipate. Weak trades will turn northeasterly as
the weakening boundary passes or stalls over the central islands,
though it appears most of the moisture should stay just east of
Hawai'i. Precipitable water values may rise slightly to about
1.2-1.3 inches over the weekend which may enhance shower activity.
By next week, another trough may approach the region from the
northwest Tue into next Wed as an upper trough or low drifts
southward near 10N. Moisture may attempt to lift northward from
the deep tropics just southeast of the Big Island in partial
response to the upper feature, but the consensus favors it to stay
offshore. By next Thu another front may approach the northwestern
islands which may disrupt the trades again. For now, a
model/ensemble consensus should suffice given the longwave
agreement in the subtropics but lesser agreement in the
mid-latitudes.

Fracasso