Hawaii Extended Forecast Discussion
NWS Weather Prediction Center College Park MD
723 AM EST Sat Dec 01 2018

Valid 00Z Sun Dec 02 2018 - 00Z Sun Dec 09 2018

Models and ensembles reasonably agree to show that amplified
mid-upper level trough passage mainly north of the state today is
forcing a cold front underneath into the islands. Blended
precipitable water imagery loops and a preferred guidance
composite indicates that deepened lead moisture plumes feeding
into the front and in advance of the front is in position to fuel
enhanced showers in a pattern with disrupted trade flow. Deep
layered high pressure settling north of the state in the wake of
frontal passage should support modest trade return through
early-mid next week as deepened moisture pooled along the stalled
frontal remains lingering near the state acts to focus some
locally enhanced showers, especially for the southern islands. The
front stalls in response to approach of another amplified
mid-upper level trough from the northwest Thursday that may also
force another moisture/shower enhancing front into the islands
late next week. However, this scenario is uncertain as guidance
solutions with respect to supporting trough amplitude aloft are
quite varied. The latest GFS/Canadian/NAVGEM and GEFS are more
amplified and less progressive than the ECMWF/UKMET and ECMWF
ensembles, but there is a minority subset of ECMWF ensemble
members that open the door for the more amplified solution within
the overall envelope of possible solutions. Given that all
guidance builds some form of a mid-upper level ridge upstream over
the subtropical west-central Pacific and recent flow history, at
least prefer a deterministic solution with more amplitude than the
ECMWF/UKMET.

Schichtel