Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
730 AM EST Mon Jan 30 2017

Valid 00Z Tue Jan 31 2017 - 00Z Tue Feb 07 2017

With a mid-latitude upper low exiting toward the Eastern Pacific,
the Hawai`ian island chain will reside in post-frontal air to
commence the period. This should ensure brisk north-northeasterly
flow at the surface before the gradient weakens in a couple of
days. A return to a trade wind regime is expected thereafter as
mid-level heights begin to build over the region. By later in the
work week, a longwave trough takes shape which affords perhaps
another frontal passage across the northern most islands. However,
this baroclinic zone should quickly shear in advance of a much
more impressive system lurking upstream. There is a general
consensus in the guidance to carry a more pronounced upper trough
east of the International Dateline by the end of the forecast
period. Ensemble spaghetti plots show sufficient agreement in this
evolution with some variation among the individual models.
Low-level southwesterly flow should really pick up in intensity by
later in the weekend, particularly as noted in the 06Z GFS
solution. In terms of precipitation threats, it should be rather
quiet in the post-frontal air mass throughout the work week.
However, showers should return to the forecast as a pair of
frontal passages approach the northern islands. This is especially
the case with the system approaching at the end of the period.


Rubin-Oster