Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
730 AM EST Tue Nov 29 2016

Valid 00Z Wed Nov 30 2016 - 00Z Wed Dec 07 2016

...Heavy Rainfall Pattern for Hawaii...


...Guidance and Uncertainty Assessment...

Prefer a composite solution of resonably well clustered model and
ensemble guidance at mid-larger scales. Smaller scale details are
more problematic at these longer time frames, but the upcoming
pattern should produce a period with excessive rainfall potential.
Overall forecast predictability in this flow evolution is above
normal.

...Weather Highlights/Threats...

Tightened pressure gradients underneath high pressure centered to
the north then northeast of the state will favor moderate to brisk
trades over the next couple of days. An area of modest moisture
moving over the islands should combine with trades to favor
windward terrain showers.

Trades should gradually weaken but shift southeastward Thursday as
closed low slides just to the south of the state. The closed low
is slated to lift slowly over the state Friday into Saturday in
response to new mid-upper level trough energy digging just to the
west of the state. This should induce inverted troughing and act
to pull/pool deep layered ITCZ based moisture over the state to
fuel an excessive rainfall and runoff threat as precipitable water
values rise to at or above 2" over the weekend into early next
week.

Schichtel