Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
730 AM EST Sun Nov 12 2017

Valid 00Z Mon Nov 13 2017 - 00Z Mon Nov 20 2017

Southern stream troughing aloft is digging southeastward over the
Hawaiian islands today. This has acted to destabilize the
atmosphere as weakened lead trades with an embedded disturbance
advects deepened lower level moisture into the state. This has
fueled some enhanced showers and local heavy downpours. Lingering
activity will focus over the Big Island later today where cooled
temperatures aloft has prompted a winter weather advisory for
Mauna Loa and Mauna Kea for elevations above 12,000 feet.

Mid-upper level reinforcing northern stream height falls dig
over/east of the state this week as a mid-upper level ridge
strongly rebuilds over the north-central Pacific in a more blocky
pattern. This acts to steadily decrease moisture and showers
statewide as strong surface high pressure builds and settles to
the north of the state. In this pattern, expect moderate then
brisk trades with only limited windward terrain showers.

Model and ensemble solutions cluster well over the next week,
bolstering forecast confidence. Considering flow amplitude
upstream, suggest a composite of the very well clustered 06 UTC
GFS and 00 UTC ECMWF/UKMET/Canadian/NAVGEM whose higher resolution
deterministic guidance offers a slightly more amplified mid-upper
level trough over/east of the islands than ensemble means.

Schichtel