Prognostic Meteorological Discussion
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FXHW01 KWNH 231230

Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
830 AM EDT Wed May 23 2018

Valid 00Z Thu May 24 2018 - 00Z Thu May 31 2018

Models and ensembles reasonably agree that subtropical ridging
will shift over Hawaii as a surface high axis stretches east-west
along 32-36N. This will maintain locally breezy trades that may
increase Thu-Fri as the surface high bridges to the north of the
state. With a relatively stable air mass and precipitable water
values near average, expect generally light windward showers
through the weekend.

Guidance offers similar pattern evolution themes into early-mid
next week, but now differ a bit more with advent and approach of
an amplifying mid-upper level trough and surface frontal system to
the northwest of the state. The latest ECMWF/UKMET dig this system
more than the GFS/Canadian and that may be more reasonable
considering the amplitude of the upstream ridge common to most
guidance. Accordingly, slow system approach would lead to
weakening/veering/moistening trades and wetter flow onset, but
details remain uncertain given forecast spread.


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