Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
830 AM EDT Fri Oct 14 2016

Valid 00Z Sat Oct 15 2016 - 00Z Sat Oct 22 2016

The beginning of the forecast period will be dominated by the
presence of a broad 594-dm ridge centered over 30N latitude. This
should be a prominent feature through the weekend before weakening
in response to lowering mid-level heights to the north. The
accompanying shortwave is expected to remain well to the north of
the Hawai`ian islands based on evaluation of all the recent model
guidance. It appears the bigger influences will be on the surface
pattern with a gradual slackening of the trade winds as the
anticyclone weakens and pressure gradients become less defined.
There is a notable signal that as the mid-latitude cyclone
advances toward the northeastern Pacific, much stronger trades are
likely toward the Thursday/Friday, October 20-21, timeframe as a
1038-mb ridge sets up to the north. Regarding precipitation, the
usual shower activity will be likely with the best focus over
favored topography as well as due to local mesoscale effects. Many
models do show a spike in precipitable water values by late
Tuesday which suggests an increase in coverage of rain showers is
possible. This is in response to a westward propagating tropical
wave noted in the guidance.


Rubin-Oster