Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
811 AM EDT Wed Oct 18 2017

Valid 00Z Thu Oct 19 2017 - 00Z Thu Oct 26 2017

Breezy trades will slowly subside by the weekend as a 1034mb
surface high moves southeastward and then eastward along 33N later
this week but weakens to about 1026mb. Generally light
windward/mauka showers are expected. Next week, a trough is
forecast to dig past 165W north of 35N but the ensembles diverge
on whether to continue digging it to/south of 30N or begin to lift
it back eastward then northeastward. The GFS/Canadian were most
aggressive with this system while the 00Z ECMWF was
quicker/weaker. The multi-center ensembles were extended even
farther southwest (deeper/slower) and northeast (quicker/weaker)
than the deterministic models, but an overall consensus seems to
be near the 00Z or 06Z GEFS mean which is closer to the 00Z ECMWF
in the subtropical central Pacific (though not as close in the
northeast Pacific). This would allow the cold front to drop
southeastward very close to the northwestern islands and also
allow southeasterly flow in the low levels to bring in more
moisture. More widespread rain would be a possibility given
instability/lift increasing as well.


Fracasso