Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
730 AM EST Wed Nov 29 2017

Valid 00Z Thu Nov 30 2017 - 00Z Thu Dec 07 2017

...Heavy Precipitation Threat...

Surface high pressure bridging to the north of the state will
reinforce a pattern supporting breezy/windy trades this week. Deep
tropical moisture banded along and just south of the state will
lift gradually northward over the next few days as a mid-upper
level shortwave trough and associated height falls digs just to
the north then northeast of the state. This will induce lead
inverted surface troughing through the state whose southeastward
veered trades increasingly tap the deep tropical moisture. This
would fuel potential for locally heavy rainfall. Flash flood
watches remain in effect over the Big Island and Maui and a winter
storm advisory is also in effect for the summits of Mauna Loa and
Mauna Kea for lingering snow. The threat may diminish over the
weekend with lead frontal passage. A second and more amplified
mid-upper level shortwave trough passage along/north of the state
next Tuesday/Wednesday and associated frontal track will further
filter drier air across the state in a pattern with disrupted
trades. Model and ensemble forecast spread and uncertainty has
decreased significantly over the past few days, bolstering
forecast confidence in a well supported guidance composite
solution.

Schichtel